Tag Archives: Instrumentation and Methods for Astrophysics

Posterior Sampling of the Initial Conditions of the Universe from Non-linear Large Scale Structures using Score-Based Generative Models [CEA]

Posted on by

http://arxiv.org/abs/2304.03788


Reconstructing the initial conditions of the universe is a key problem in cosmology. Methods based on simulating the forward evolution of the universe have provided a way to infer initial conditions consistent with present-day observations. However, due to the high complexity of the inference problem, these methods either fail to sample a distribution of possible initial density fields or require significant approximations in the simulation model to be tractable, potentially leading to biased results. In this work, we propose the use of score-based generative models to sample realizations of the early universe given present-day observations. We infer the initial density field of full high-resolution dark matter N-body simulations from the present-day density field and verify the quality of produced samples compared to the ground truth based on summary statistics. The proposed method is capable of providing plausible realizations of the early universe density field from the initial conditions posterior distribution marginalized over cosmological parameters and can sample orders of magnitude faster than current state-of-the-art methods.

Read this paper on arXiv…

R. Legin, M. Ho, P. Lemos, et. al.
Tue, 11 Apr 23
63/63

Comments: 8 pages, 7 figures

Triumvirate: A Python/C++ package for three-point clustering measurements [IMA]

Posted on by

http://arxiv.org/abs/2304.03643


Triumvirate is a Python/C++ package for measuring the three-point clustering statistics in large-scale structure (LSS) cosmological analyses. Given a catalogue of discrete particles (such as galaxies) with their spatial coordinates, it computes estimators of the multipoles of the three-point correlation function, also known as the bispectrum in Fourier space, in the tri-polar spherical harmonic (TripoSH) decomposition proposed by Sugiyama et al. (2019). The objective of Triumvirate is to provide efficient end-to-end measurement of clustering statistics which can be fed into downstream galaxy survey analyses to constrain and test cosmological models. To this end, it builds upon the original algorithms in the hitomi code developed by Sugiyama et al. (2018, 2019), and supplies a user-friendly interface with flexible input/output (I/O) of catalogue data and measurement results, with the built program configurable through external parameter files and tracked through enhanced logging and warning/exception handling. For completeness and complementarity, methods for measuring two-point clustering statistics are also included in the package.

Read this paper on arXiv…

M. Wang, F. Beutler and N. Sugiyama
Mon, 10 Apr 23
6/36

Comments: 5 pages. Submitted to JOSS. Code available at this https URL

Super-resolution imaging for the detection of low-energy ion tracks in fine-grained nuclear emulsions [IMA]

Posted on by

http://arxiv.org/abs/2304.03645


We propose a new wide-field imaging method that exploits the Localized Surface Plasmon Resonance phenomenon to produce super-resolution images with an optical microscope equipped with a custom design polarization analyzer module. In this paper we describe the method and apply it to the analysis of low-energy carbon ion tracks implanted in a nuclear emulsion film. The result is then compared with the measurements of the same tracks carried out at an electronic microscope. The images set side by side show their close similarity. The resolution achieved with the current microscope setup is estimated to be about 60 nm.

Read this paper on arXiv…

A. Alexandrov, T. Asada, F. Borbone, et. al.
Mon, 10 Apr 23
17/36

Comments: 13 pages, 10 figures

Direct Exoplanet Detection Using L1 Norm Low-Rank Approximation [IMA]

Posted on by

http://arxiv.org/abs/2304.03619


We propose to use low-rank matrix approximation using the component-wise L1-norm for direct imaging of exoplanets. Exoplanet detection is a challenging task for three main reasons: (1) the host star is several orders of magnitude brighter than exoplanets, (2) the angular distance between exoplanets and star is usually very small, and (3) the speckles are very similar to the exoplanet signal both in shape and intensity. First, we empirically examine the statistical noise assumptions of the models, second, we evaluate the performance of the proposed L1 low-rank approximation (L1-LRA) algorithm based on visual comparisons and receiver operating characteristic (ROC) curves. We compare the results of the L1-LRA with the widely used truncated singular value decomposition (SVD) based on the L2 norm in two different annuli, one close to the star and one far away.

Read this paper on arXiv…

H. Daglayan, S. Vary, V. Leplat, et. al.
Mon, 10 Apr 23
21/36

Comments: 5 pages, 3 figures

Machine learning-based seeing estimation and prediction using multi-layer meteorological data at Dome A, Antarctica [IMA]

Posted on by

http://arxiv.org/abs/2304.03587


Atmospheric seeing is one of the most important parameters for evaluating and monitoring an astronomical site. Moreover, being able to predict the seeing in advance can guide observing decisions and significantly improve the efficiency of telescopes. However, it is not always easy to obtain long-term and continuous seeing measurements from a standard instrument such as differential image motion monitor (DIMM), especially for those unattended observatories with challenging environments such as Dome A, Antarctica. In this paper, we present a novel machine learning-based framework for estimating and predicting seeing at a height of 8 m at Dome A, Antarctica, using only the data from a multi-layer automated weather station (AWS). In comparison with DIMM data, our estimate has a root mean square error (RMSE) of 0.18 arcsec, and the RMSE of predictions 20 minutes in the future is 0.12 arcsec for the seeing range from 0 to 2.2 arcsec. Compared with the persistence, where the forecast is the same as the last data point, our framework reduces the RMSE by 37 percent. Our method predicts the seeing within a second of computing time, making it suitable for real-time telescope scheduling.

Read this paper on arXiv…

X. Hou, Y. Hu, F. Du, et. al.
Mon, 10 Apr 23
26/36

Comments: 13 pages, 14 figures, accepted for publication in Astronomy and Computing

Principal Component Analysis of Ground Level Enhancement of Cosmic Ray Events [HEAP]

Posted on by

http://arxiv.org/abs/2304.03695


We applied principal component analysis (PCA) to the study of five ground level enhancement (GLE) of cosmic ray (CR) events. The nature of the multivariate data involved makes PCA a useful tool for this study. A subroutine program written and implemented in R software environment generated interesting principal components. Analysis of the results shows that the method can distinguish between neutron monitors (NMs) that observed Forbush decrease (FD) from those that observed GLE at the same time. The PCA equally assigned NMs with identical signal counts with the same correlation factor (r) and those with close r values equally have a close resemblance in their CR counts. The results further indicate that while NMs that have the same time of peak may not have the same r, most NMs that had the same r also had the same time of peak. Analyzing the second principal components yielded information on the differences between NMs having opposite but the same or close values of r. NMs that had the same r equally had the tendency of being in close latitude.

Read this paper on arXiv…

R. Ugwoke, A. Ubachukwu, J. Urama, et. al.
Mon, 10 Apr 23
29/36

Comments: N/A

Upper limits on transmitter rate of extragalactic civilizations placed by Breakthrough Listen observations [HEAP]

Posted on by

http://arxiv.org/abs/2304.02756


The Search for Extra-Terrestrial Intelligence (SETI) has been conducted for over sixty years, yet no technosignatures have been identified. Previous studies have focused on stars in our galaxy, with few searches in the extragalactic Universe despite a larger volume being available. Civilizations capable of harvesting energy from a star or a galaxy are classified as KII or KIII on the Kardashev scale, respectively. Technosignatures from such advanced civilizations would be extremely luminous and detectable by current radio telescopes, even from distant galaxies. To explore the frontier of extragalactic SETI, we investigate the likely prevalence of extragalactic civilizations possessing a radio transmitter, known as the transmitter rate, based on observational results from the Breakthrough Listen (BL) observations. We calculated the transmitter rate by considering the background galaxies in the field of view of target stars in BL observations. We used a statistical method to derive the total mass of stars in those background galaxies from a galaxy stellar mass function. Our statistical method suggests that less than one in hundreds of trillions of extragalactic civilizations within 969 Mpc possess a radio transmitter above 7.7$\times$10$^{26}$ W of power, assuming one civilization per one-solar-mass stellar system. Additionally, we cross-matched the BL survey fields with the WISE$\times$SuperCOSMOS Photometric Redshift Catalogue and compared with the statistical method. Our result sets the strictest limits to date on the transmitter rate at such high power levels, emphasizing the high efficiency of searching for radio transmitters in galaxies and the rarity of technologically advanced civilizations in our Universe.

Read this paper on arXiv…

Y. Uno, T. Hashimoto, T. Goto, et. al.
Fri, 7 Apr 23
1/50

Comments: 5 pages, 1 figure, accepted for publication in MNRAS

Full Resolution Deconvolution of Complex Faraday Spectra [IMA]

Posted on by

http://arxiv.org/abs/2304.02728


Polarized synchrotron emission from multiple Faraday depths can be separated by calculating the complex Fourier transform of the Stokes’ parameters as a function of the wavelength squared, known as Faraday Synthesis. As commonly implemented, the transform introduces an additional term $\lambda_0^2$, which broadens the real and imaginary spectra, but not the amplitude spectrum. We use idealized tests to investigate whether additional information can be recovered with a clean process restoring beam set to the narrower width of the peak in the real “full” resolution spectrum with $\lambda_0^2=0$. We find that the $\lambda_0^2$ choice makes no difference, except for the use of a smaller restoring beam. With this smaller beam, the accuracy and phase stability are unchanged for single Faraday components. However, using the smaller restoring beam for multiple Faraday components we find a) better discrimination of the components, b) significant reductions in blending of structures in tomography images, and c) reduction of spurious features in the Faraday spectra and tomography maps. We also discuss the limited accuracy of information on scales comparable to the width of the amplitude spectrum peak, and note a clean-bias, reducing the recovered amplitudes. We present examples using MeerKAT L-band data. We also revisit the maximum width in Faraday depth to which surveys are sensitive, and introduce the variable $W_{max}$, the width for which the power drops by a factor of 2. We find that most surveys cannot resolve continuous Faraday distributions unless the narrower full restoring beam is used.

Read this paper on arXiv…

L. Rudnick and W. Cotton
Fri, 7 Apr 23
9/50

Comments: 17 pages, 23 figures, accepted for publication in MNRAS, 4 April, 2023

The Colorado Ultraviolet Transit Experiment (CUTE) signal to noise calculator [IMA]

Posted on by

http://arxiv.org/abs/2304.02776


We present here the signal-to-noise (S/N) calculator developed for the Colorado Ultraviolet Transit Experiment (CUTE) mission. CUTE is a 6U CubeSat operating in the near-ultraviolet (NUV) observing exoplanetary transits to study their upper atmospheres. CUTE was launched into a low-Earth orbit in September 2021 and it is currently gathering scientific data. As part of the S/N calculator, we also present the error propagation for computing transit depth uncertainties starting from the S/N of the original spectroscopic observations. The CUTE S/N calculator is currently extensively used for target selection and scheduling. The modular construction of the CUTE S/N calculator enables its adaptation and can be used also for other missions and instruments.

Read this paper on arXiv…

A. Sreejith, L. Fossati, P. Cubillos, et. al.
Fri, 7 Apr 23
19/50

Comments: Accepted for publication in Astrophysics and Space Science

The Large Array Survey Telescope — Science Goals [IMA]

Posted on by

http://arxiv.org/abs/2304.02719


The Large Array Survey Telescope (LAST) is designed to survey the variable and transient sky at high temporal cadence. The array is comprised of 48 F/2.2 telescopes of 27.9cm aperture, coupled to full-frame backside-illuminated cooled CMOS detectors with $3.76$$\mu$m pixels, resulting in a pixel scale of $1.25\mathrm{arcsec}$. A single telescope with a field of view of $7.4\mathrm{deg}^2$ reaches a $5\sigma$ limiting magnitude of $19.6$ in $20$s. LAST 48 telescopes are mounted on 12 independent mounts — a modular design which allows us to conduct optimized parallel surveys. Here we provide a detailed overview of the LAST survey strategy and its key scientific goals. These include the search for gravitational-wave (GW) electromagnetic counterparts with a system that can cover the uncertainty regions of the next-generation GW detectors in a single exposure, the study of planetary systems around white dwarfs, and the search for near-Earth objects. LAST is currently being commissioned, with full scientific operations expected in mid 2023. This paper is accompanied by two complementary publications in this issue, giving an overview of the system (Ofek et al. 2023a) and of the dedicated data reduction pipeline (Ofek et al. 2023b).

Read this paper on arXiv…

S. Ben-Ami, E. Ofek, D. Polishook, et. al.
Fri, 7 Apr 23
23/50

Comments: N/A

Photometry of outer Solar System objects from the Dark Energy Survey I: photometric methods, light curve distributions and trans-Neptunian binaries [EPA]

Posted on by

http://arxiv.org/abs/2304.03017


We report the methods of and initial scientific inferences from the extraction of precision photometric information for the $>800$ trans-Neptunian objects (TNOs) discovered in the images of the Dark Energy Survey (DES). Scene-modelling photometry is used to obtain shot-noise-limited flux measures for each exposure of each TNO, with background sources subtracted. Comparison of double-source fits to the pixel data with single-source fits are used to identify and characterize two binary TNO systems. A Markov Chain Monte Carlo method samples the joint likelihood of the intrinsic colors of each source as well as the amplitude of its flux variation, given the time series of multiband flux measurements and their uncertainties. A catalog of these colors and light curve amplitudes $A$ is included with this publication. We show how to assign a likelihood to the distribution $q(A)$ of light curve amplitudes in any subpopulation. Using this method, we find decisive evidence (i.e. evidence ratio $<0.01$) that cold classical (CC) TNOs with absolute magnitude $6<H_r<8.2$ are more variable than the hot classical (HC) population of the same $H_r$, reinforcing theories that the former form in situ and the latter arise from a different physical population. Resonant and scattering TNOs in this $H_r$ range have variability consistent with either the HC’s or CC’s. DES TNOs with $H_r<6$ are seen to be decisively less variable than higher-$H_r$ members of any dynamical group, as expected. More surprising is that detached TNOs are decisively less variable than scattering TNOs, which requires them to have distinct source regions or some subsequent differential processing.

Read this paper on arXiv…

P. Bernardinelli, G. Bernstein, N. Jindal, et. al.
Fri, 7 Apr 23
43/50

Comments: Submitted to AAS journals, data release forthcoming and will be included in journal version

Improving pulsar-timing solutions through dynamic pulse fitting [IMA]

Posted on by

http://arxiv.org/abs/2304.02793


Precision pulsar timing is integral to the detection of the nanohertz stochastic gravitational-wave background as well as understanding the physics of neutron stars. Conventional pulsar timing often uses fixed time and frequency-averaged templates to determine the pulse times of arrival, which can lead to reduced accuracy when the pulse profile evolves over time. We illustrate a dynamic timing method that fits each observing epoch using basis functions. By fitting each epoch separately, we allow for the evolution of the pulse shape epoch to epoch. We apply our method to PSR J1103$-$5403 and demonstrate that it undergoes mode changing, making it the fourth millisecond pulsar to exhibit such behaviour. Our method, which is able to identify and time a single mode, yields a timing solution with a root-mean-square error of 1.343 $\mu \mathrm{s}$, a factor of 1.78 improvement over template fitting on both modes. In addition, the white-noise amplitude is reduced 4.3 times, suggesting that fitting the full data set causes the mode changing to be incorrectly classified as white noise. This reduction in white noise boosts the signal-to-noise ratio of a gravitational-wave background signal for this particular pulsar by 32%. We discuss the possible applications for this method of timing to study pulsar magnetospheres and further improve the sensitivity of searches for nanohertz gravitational waves.

Read this paper on arXiv…

R. Nathan, M. Miles, G. Ashton, et. al.
Fri, 7 Apr 23
48/50

Comments: 8 pages, 8 figures

Deep learning approach for identification of HII regions during reionization in 21-cm observations — II. foreground contamination [IMA]

Posted on by

http://arxiv.org/abs/2304.02661


The upcoming Square Kilometre Array Observatory (SKAO) will produce images of neutral hydrogen distribution during the epoch of reionization by observing the corresponding 21-cm signal. However, the 21-cm signal will be subject to instrumental limitations such as noise, foreground contamination, and limited resolution, which pose a challenge for accurate detection. In this study, we present the \texttt{SegU-Net v2} framework, which is an enhanced version of our U-Net architecture-based convolutional neural network built for segmenting image data into meaningful features. This framework is designed to identify neutral and ionized regions in the 21-cm signal contaminated with foreground emission that is $\sim$3 order of magnitude larger. We demonstrate the effectiveness of our method by estimating the true ionization history from mock observations of SKA with an observation time of 1000 h, achieving an average classification accuracy of 71 per cent. As the photon sources driving reionization are expected to be located inside the ionised regions identified by \texttt{SegU-Net v2}, this tool can be used to identify locations for follow-up studies with infrared/optical telescopes to detect these sources. Additionally, we derive summary statistics, such as the size distribution of neutral islands, from evaluating the reliability of our method on the tomographic data expected from the SKA-Low. Our study suggests that \texttt{SegU-Net v2} can be a stable and reliable tool for analyzing the 3D tomographic data produced by the SKA and recovering important information about the non-Gaussian nature of the reionization process.

Read this paper on arXiv…

M. Bianco, S. Giri, D. Prelogović, et. al.
Fri, 7 Apr 23
49/50

Comments: 16 pages, 9 figures, 2 tables. Comments welcome

The Next Generation Event Horizon Telescope Collaboration: History, Philosophy, and Culture [CL]

Posted on by

http://arxiv.org/abs/2304.02463


This white paper outlines the plans of the History Philosophy Culture Working Group of the Next Generation Event Horizon Telescope Collaboration.

Read this paper on arXiv…

P. Galison, J. Doboszewski, J. Elder, et. al.
Thu, 6 Apr 23
3/76

Comments: 23 pages, 1 figure

Albatross: A scalable simulation-based inference pipeline for analysing stellar streams in the Milky Way [GA]

Posted on by

http://arxiv.org/abs/2304.02032


Stellar streams are potentially a very sensitive observational probe of galactic astrophysics, as well as the dark matter population in the Milky Way. On the other hand, performing a detailed, high-fidelity statistical analysis of these objects is challenging for a number of key reasons. Firstly, the modelling of streams across their (potentially billions of years old) dynamical age is complex and computationally costly. Secondly, their detection and classification in large surveys such as Gaia renders a robust statistical description regarding e.g., the stellar membership probabilities, challenging. As a result, the majority of current analyses must resort to simplified models that use only subsets or summaries of the high quality data. In this work, we develop a new analysis framework that takes advantage of advances in simulation-based inference techniques to perform complete analysis on complex stream models. To facilitate this, we develop a new, modular dynamical modelling code sstrax for stellar streams that is highly accelerated using jax. We test our analysis pipeline on a mock observation that resembles the GD1 stream, and demonstrate that we can perform robust inference on all relevant parts of the stream model simultaneously. Finally, we present some outlook as to how this approach can be developed further to perform more complete and accurate statistical analyses of current and future data.

Read this paper on arXiv…

J. Alvey, M. Gerdes and C. Weniger
Thu, 6 Apr 23
6/76

Comments: 17 pages, 6 figures. Codes: sstrax available for download at this https URL, albatross at this https URL

Simulation of CSSTs astrometric capability [IMA]

Posted on by

http://arxiv.org/abs/2304.02196


The China Space Station Telescope (CSST) will enter a low Earth orbit around 2024 and operate for 10 years, with seven of those years devoted to surveying the area of the median-to-high Galactic latitude and median-to-high Ecliptic latitude of the sky. To maximize the scientific output of CSST, it is important to optimize the survey schedule. We aim to evaluate the astrometric capability of CSST for a given survey schedule and to provide independent suggestions for the optimization of the survey strategy. For this purpose, we first construct the astrometric model and then conduct simulated observations based on the given survey schedule. The astrometric solution is obtained by analyzing the simulated observation data. And then we evaluate the astrometric capability of CSST by analyzing the properties of the astrometric solution. We find that the accuracy of parallax and proper motion of CSST is better than 1 mas( yr1) for the sources of 18-22 mag in g band, and about 1-10 mas( yr1) for the sources of 22-26 mag in g band, respectively. The results from real survey could be worse since the assumptions are optimistic and simple. We find that optimizing the survey schedule can improve the astrometric accuracy of CSST. In the future, we will improve the astrometric capability of CSST by continuously iterating and optimizing the survey schedule.

Read this paper on arXiv…

Z. Fu, Z. Qi, S. Liao, et. al.
Thu, 6 Apr 23
26/76

Comments: 17 pages, 10 figures

Peregrine: Sequential simulation-based inference for gravitational wave signals [CL]

Posted on by

http://arxiv.org/abs/2304.02035


The current and upcoming generations of gravitational wave experiments represent an exciting step forward in terms of detector sensitivity and performance. For example, key upgrades at the LIGO, Virgo and KAGRA facilities will see the next observing run (O4) probe a spatial volume around four times larger than the previous run (O3), and design implementations for e.g. the Einstein Telescope, Cosmic Explorer and LISA experiments are taking shape to explore a wider frequency range and probe cosmic distances. In this context, however, a number of very real data analysis problems face the gravitational wave community. For example, it will be crucial to develop tools and strategies to analyse (amongst other scenarios) signals that arrive coincidentally in detectors, longer signals that are in the presence of non-stationary noise or other shorter transients, as well as noisy, potentially correlated, coherent stochastic backgrounds. With these challenges in mind, we develop peregrine, a new sequential simulation-based inference approach designed to study broad classes of gravitational wave signal. In this work, we describe the method and implementation, before demonstrating its accuracy and robustness through direct comparison with established likelihood-based methods. Specifically, we show that we are able to fully reconstruct the posterior distributions for every parameter of a spinning, precessing compact binary coalescence using one of the most physically detailed and computationally expensive waveform approximants (SEOBNRv4PHM). Crucially, we are able to do this using only 2\% of the waveform evaluations that are required in e.g. nested sampling approaches. Finally, we provide some outlook as to how this level of simulation efficiency and flexibility in the statistical analysis could allow peregrine to tackle these current and future gravitational wave data analysis problems.

Read this paper on arXiv…

U. Bhardwaj, J. Alvey, B. Miller, et. al.
Thu, 6 Apr 23
27/76

Comments: 14 pages, 5 figures. Code: peregrine available at this https URL

Next-Level, Robotic Telescope-Based Observing Experiences to Boost STEM Enrollments and Majors on a National Scale: Year 1 Report [IMA]

Posted on by

http://arxiv.org/abs/2304.02545


Funded by a $3M Department of Defense (DoD) National Defense Education Program (NDEP) award, we are developing and deploying on a national scale a follow-up curriculum to “Our Place In Space!”, or OPIS!, in which approx. 3,500 survey-level astronomy students are using our global network of “Skynet” robotic telescopes each year. The goal of this new curriculum, called “Astrophotography of the Multi-Wavelength Universe!”, or MWU!, is to boost the number of these students who choose STEM majors. During Y1, our participating educators have developed MWU!’s (now renumbered) 2nd and 4th modules, and are in the process of developing its 3rd and 7th modules (out of 7). Solid progress has also been made on the software front, (1) where we have developed new graphing/analysis/modeling interfaces in support of Modules 2 and 4, and in response to feedback from the participating educators; and (2) where we are in the process of developing and adding astrophotography capabilities to Afterglow Access (AgA), our student-level, web-based, image processing and analysis application, in support of Modules 1 – 3 and 5 – 7. On the hardware front, development of our first four signal-processing units proceeds on schedule; these are key to Skynet’s integration of a global network of radio telescopes, capable of exploring the invisible universe. Preparations have also been made on the evaluation and accessibility fronts, for when the first MWU! modules are deployed in Spring 2023.

Read this paper on arXiv…

D. Reichart, J. Haislip, V. Kouprianov, et. al.
Thu, 6 Apr 23
29/76

Comments: 10 pages, 9 figures, ASP2022 Conference Proceedings, December 2022

Polarization aberrations in next-generation giant segmented mirror telescopes (GSMTs) I. Effect on the coronagraphic performance [IMA]

Posted on by

http://arxiv.org/abs/2304.02079


Next-generation large segmented mirror telescopes are expected to perform direct imaging and characterization of Earth-like rocky planets, which requires contrast limits of $10^{-7}$ to $10^{-8}$ at wavelengths from I to J band. One critical aspect affecting the raw on-sky contrast are polarization aberrations arising from the reflection from the telescope’s mirror surfaces and instrument optics. We simulate the polarization aberrations and estimate their effect on the achievable contrast for three next-generation ground-based large segmented mirror telescopes. We performed ray-tracing in Zemax and computed the polarization aberrations and Jones pupil maps using the polarization ray-tracing algorithm. The impact of these aberrations on the contrast is estimated by propagating the Jones pupil maps through a set of idealized coronagraphs using hcipy, a physical optics-based simulation framework. The optical modeling of the giant segmented mirror telescopes (GSMTs) shows that polarization aberrations create significant leakage through a coronagraphic system. The dominant aberration is retardance defocus, which originates from the steep angles on the primary and secondary mirrors. The retardance defocus limits the contrast to $10^{-5}$ to $10^{-4}$ at 1 $\lambda/D$ at visible wavelengths, and $10^{-5}$ to $10^{-6}$ at infrared wavelengths. The simulations also show that the coating plays a major role in determining the strength of the aberrations. Polarization aberrations will need to be considered during the design of high-contrast imaging instruments for the next generation of extremely large telescopes. This can be achieved either through compensation optics, robust coronagraphs, specialized coatings, calibration, and data analysis approaches or by incorporating polarimetry with high-contrast imaging to measure these effects.

Read this paper on arXiv…

R. Anche, J. Ashcraft, S. Haffert, et. al.
Thu, 6 Apr 23
36/76

Comments: 18 pages, 12 figures, Accepted in Astronomy & Astrophysics manuscript no. aa45651-22

The Enhanced Resolution Imager and Spectrograph for the VLT [IMA]

Posted on by

http://arxiv.org/abs/2304.02343


ERIS, the Enhanced Resolution Imager and Spectrograph, is an instrument that both extends and enhances the fundamental diffraction limited imaging and spectroscopy capability for the VLT. It replaces two instruments that were being maintained beyond their operational lifetimes, combines their functionality on a single focus, provides a new wavefront sensing module for natural and laser guide stars that makes use of the Adaptive Optics Facility, and considerably improves on their performance. The observational modes ERIS provides are integral field spectroscopy at 1-2.5 {\mu}m, imaging at 1-5 {\mu}m with several options for high contrast imaging, and longslit spectroscopy at 3-4 {\mu}m, The instrument is installed at the Cassegrain focus of UT4 at the VLT and, following its commissioning during 2022, has been made available to the community.

Read this paper on arXiv…

R. Davies, O. Absil, G. Agapito, et. al.
Thu, 6 Apr 23
49/76

Comments: 19 pages with 29 figures; submitted to A&A

Low-loss Si-based Dielectrics for High Frequency Components of Superconducting Detectors [IMA]

Posted on by

http://arxiv.org/abs/2304.01362


Silicon-based dielectric is crucial for many superconducting devices, including high-frequency transmission lines, filters, and resonators. Defects and contaminants in the amorphous dielectric and at the interfaces between the dielectric and metal layers can cause microwave losses and degrade device performance. Optimization of the dielectric fabrication, device structure, and surface morphology can help mitigate this problem. We present the fabrication of silicon oxide and nitride thin film dielectrics. We then characterized them using Scanning Electron Microscopy, Atomic Force Microscopy, and spectrophotometry techniques. The samples were synthesized using various deposition methods, including Plasma-Enhanced Chemical Vapor Deposition and magnetron sputtering. The films morphology and structure were modified by adjusting the deposition pressure and gas flow. The resulting films were used in superconducting resonant systems consisting of planar inductors and capacitors. Measurements of the resonator properties, including their quality factor, were performed.

Read this paper on arXiv…

M. Lisovenko, Z. Pan, P. Barry, et. al.
Wed, 5 Apr 23
17/62

Comments: 4 pages, 5 figures, conference

Heating and dynamics of the Solar atmosphere [SSA]

Posted on by

http://arxiv.org/abs/2304.01553


The solar atmosphere shows anomalous variation in temperature, starting from the 5500 K photosphere to the million-degree Kelvin corona. The corona itself expands into the interstellar medium as the free streaming solar wind, which modulates and impacts the near-Earth space weather. The precise source regions of different structures in the solar wind, their formation height, and the heating of the solar atmosphere are inextricably linked and unsolved problems in astrophysics. Observations suggest correlations between Coronal holes (CHs), which are cool, intensity deficit structures in the solar corona, with structures in the solar wind. Observations also suggest the local plasma heating in the corona through power-law distributed impulsive events. In this thesis, we use narrowband photometric, spectroscopic, and disc-integrated emission of the solar atmosphere ranging from Near Ultraviolet to X-rays along with in-situ solar wind measurements to understand (i). the source regions of the solar wind, (ii). the underlying mechanism of solar coronal heating, and (iii). the differentiation in dynamics of CHs with the background Quiet Sun (QS) regions, which do not show any significant signature of the solar wind. We leverage machine learning and numerical modeling tools to develop solar wind forecasting codes using interpretable AI, inversion codes to infer the properties of impulsive events and to understand the differences in the thermodynamics of CHs and QS regions. We finally present a unified scenario of solar wind emergence and heating in the solar atmosphere and discuss the implications of inferences from this thesis.

Read this paper on arXiv…

V. Upendran
Wed, 5 Apr 23
44/62

Comments: PhD thesis presented to IUCAA and JNU. Refer to the thesis for list of papers

Fabrication of a Monolithic 5-Meter Aluminum Reflector for Millimeter-Wavelength Observations of the Cosmic Microwave Background [IMA]

Posted on by

http://arxiv.org/abs/2304.01469


We have demonstrated the fabrication of a monolithic, 5-meter diameter, aluminum reflector with 17.4 $\mu$m RMS surface error. The reflector was designed to avoid the problem of pickup due to scattering from panel gaps in a large, millimeter-wavelength telescope that will be used for measurements on the cosmic microwave background.

Read this paper on arXiv…

T. Natoli, B. Benson, J. Carlstrom, et. al.
Wed, 5 Apr 23
46/62

Comments: N/A

Astronomical image time series classification using CONVolutional attENTION (ConvEntion) [IMA]

Posted on by

http://arxiv.org/abs/2304.01236


Aims. The treatment of astronomical image time series has won increasing attention in recent years. Indeed, numerous surveys following up on transient objects are in progress or under construction, such as the Vera Rubin Observatory Legacy Survey for Space and Time (LSST), which is poised to produce huge amounts of these time series. The associated scientific topics are extensive, ranging from the study of objects in our galaxy to the observation of the most distant supernovae for measuring the expansion of the universe. With such a large amount of data available, the need for robust automatic tools to detect and classify celestial objects is growing steadily. Methods. This study is based on the assumption that astronomical images contain more information than light curves. In this paper, we propose a novel approach based on deep learning for classifying different types of space objects directly using images. We named our approach ConvEntion, which stands for CONVolutional attENTION. It is based on convolutions and transformers, which are new approaches for the treatment of astronomical image time series. Our solution integrates spatio-temporal features and can be applied to various types of image datasets with any number of bands. Results. In this work, we solved various problems the datasets tend to suffer from and we present new results for classifications using astronomical image time series with an increase in accuracy of 13%, compared to state-of-the-art approaches that use image time series, and a 12% increase, compared to approaches that use light curves.

Read this paper on arXiv…

A. Bairouk, M. Chaumont, D. Fouchez, et. al.
Wed, 5 Apr 23
49/62

Comments: N/A

A Field-Level Multi-Probe Analysis of the CMB, ISW, and the Galaxy Density Maps [CEA]

Posted on by

http://arxiv.org/abs/2304.01387


Extracting information from cosmic surveys is often done in a two-step process, construction of maps and then summary statistics such as two-point functions. We use simulations to demonstrate the advantages of a general Bayesian framework that consistently combines different cosmological experiments on the field level, and reconstructs both the maps and cosmological parameters. We apply our method to jointly reconstruct the primordial CMB, the Integrated Sachs Wolfe effect, and 6 tomographic galaxy density maps on the full sky on large scales along with several cosmological parameters. While the traditional maximum a posterior estimator has both 2-point level and field-level bias, the new approach yields unbiased cosmological constraints and improves the signal-to-noise ratio of the maps.

Read this paper on arXiv…

A. Zhou and S. Dodelson
Wed, 5 Apr 23
50/62

Comments: N/A

Approaches for Retrieving Sulfur Species Abundances from Dual X/Ka Band Radio Occultations of Venus with EnVision and VERITAS [EPA]

Posted on by

http://arxiv.org/abs/2304.02006


The EnVision and VERITAS missions to Venus will fly with X and Ka band telecommunications channels which can be used to conduct radio occultation studies of Venus’ atmosphere. While link attenuation measurements during prior S and X band occultation experiments have been used to determine vertical profiles of H$_2$SO$_4$ vapor abundance, the addition of the Ka band channel introduces greater sensitivity to the abundances of H$_2$SO$_4$ aerosols and SO$_2$ gas, permitting retrieval of their vertical profiles from dual band measurements. Such measurements would be valuable in the assessment of chemical and dynamical processes governing short and long-term variability in Venus’ atmosphere. This paper considers the sensitivity of the X/Ka band radio attenuation measurement to these atmospheric constituents, as well as uncertainties and regularization approaches for conducting retrievals of these atmospheric sulfur species from future occultation experiments. We introduce methods for seeding maximum likelihood estimation retrievals using shape models and simple atmospheric transport constraints. From simulated retrievals, we obtain mean errors of the order of 0.5 ppm, 20 ppm, and 10 mg/m$^3$ for H$_2$SO$_4$ vapor, SO$_2$, and H$_2$SO$_4$ aerosol abundances, respectively, for simultaneous retrieval.

Read this paper on arXiv…

A. Akins, T. Bocanegra-Bahamón, K. Wang, et. al.
Wed, 5 Apr 23
60/62

Comments: 29 pages, 11 figures, accepted to PSJ

Denoising Diffusion Probabilistic Models to Predict the Density of Molecular Clouds [GA]

Posted on by

http://arxiv.org/abs/2304.01670


We introduce the state-of-the-art deep learning Denoising Diffusion Probabilistic Model (DDPM) as a method to infer the volume or number density of giant molecular clouds (GMCs) from projected mass surface density maps. We adopt magnetohydrodynamic simulations with different global magnetic field strengths and large-scale dynamics, i.e., noncolliding and colliding GMCs. We train a diffusion model on both mass surface density maps and their corresponding mass-weighted number density maps from different viewing angles for all the simulations. We compare the diffusion model performance with a more traditional empirical two-component and three-component power-law fitting method and with a more traditional neural network machine learning approach (CASI-2D). We conclude that the diffusion model achieves an order of magnitude improvement on the accuracy of predicting number density compared to that by other methods. We apply the diffusion method to some example astronomical column density maps of Taurus and the Infrared Dark Clouds (IRDCs) G28.37+0.07 and G35.39-0.33 to produce maps of their mean volume densities.

Read this paper on arXiv…

D. Xu, J. Tan, C. Hsu, et. al.
Wed, 5 Apr 23
62/62

Comments: ApJ accepted

JWST MIRI Imaging Data Post-Processing Preliminary Study with Fourier Transformation to uncover potentially celestial-origin signals [IMA]

Posted on by

http://arxiv.org/abs/2304.00728


This manuscript reports a part of a dedicated study aiming to disentangle sources of signals from James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) imaging mode. An instrumental introduction and characteristics section is present regarding MIRI. Later, a Fast Fourier Transformation-based filtering approach and its results will be discussed.

Read this paper on arXiv…

G. Hatipoğlu
Tue, 4 Apr 23
4/111

Comments: 16 pages, 18 figures

The High-Altitude Water Cherenkov (HAWC) Observatory in México: The Primary Detector [HEAP]

Posted on by

http://arxiv.org/abs/2304.00730


The High-Altitude Water Cherenkov (HAWC) observatory is a second-generation continuously operated, wide field-of-view, TeV gamma-ray observatory. The HAWC observatory and its analysis techniques build on experience of the Milagro experiment in using ground-based water Cherenkov detectors for gamma-ray astronomy. HAWC is located on the Sierra Negra volcano in M\’exico at an elevation of 4100 meters above sea level. The completed HAWC observatory principal detector (HAWC) consists of 300 closely spaced water Cherenkov detectors, each equipped with four photomultiplier tubes to provide timing and charge information to reconstruct the extensive air shower energy and arrival direction. The HAWC observatory has been optimized to observe transient and steady emission from sources of gamma rays within an energy range from several hundred GeV to several hundred TeV. However, most of the air showers detected are initiated by cosmic rays, allowing studies of cosmic rays also to be performed. This paper describes the characteristics of the HAWC main array and its hardware.

Read this paper on arXiv…

H. Collaboration
Tue, 4 Apr 23
6/111

Comments: 39 pages, 14 Figures

La inserción de la Astronomía Cultural en la educación formal: fundamentos y propósitos [CL]

Posted on by

http://arxiv.org/abs/2304.01113


There are vast educational research works that highlight the serious difficulties that students present in learning astronomical subjects, as well as the prevalence of a traditional education distanced from the observational and experiential, thus accentuating the difficulties detected. We argue that progressive teaching with a topocentric and contextualized approach would favor the motivation of the students, the construction of a more real view of current science and a more active role in the learning process. Cultural Astronomy (CA) is an academic discipline that seeks to understand the multiple ways in which societies relate to celestial objects and phenomena. For this reason, we consider that it would be a powerful resource for teaching, since it provides tools for contextualization and allows working with sky experiences linked to “naked eye astronomy”, which requires little or no instruments. It should be noted that CA involves aspects of archaeoastronomy, ethnoastronomy and the history of astronomy, thus offering multiple dimensions to take into account. The present work seeks to base the incorporation of CA studies for astronomy teaching in secondary and tertiary education.

Read this paper on arXiv…

J. Bastero, F. Karaseur, S. Garofalo, et. al.
Tue, 4 Apr 23
23/111

Comments: Article in Spanish. Published version available at this http URL

The Timing System of LIGO Discoveries [IMA]

Posted on by

http://arxiv.org/abs/2304.01188


LIGO’s mission critical timing system has enabled gravitational wave and multi-messenger astrophysical discoveries as well as the rich science extracted. Achieving optimal detector sensitivity, detecting transient gravitational waves, and especially localizing gravitational wave sources, the underpinning of multi-messenger astrophysics, all require proper gravitational wave data time-stamping. Measurements of the relative arrival times of gravitational waves between different detectors allow for coherent gravitational wave detections, localization of gravitational wave sources, and the creation of skymaps. The carefully designed timing system achieves these goals by mitigating phase noise to avoid signal up-conversion and maximize gravitational wave detector sensitivity. The timing system also redundantly performs self-calibration and self-diagnostics in order to ensure reliable, extendable, and traceable time stamping. In this paper, we describe and quantify the performance of these core systems during the latest O3 scientific run of LIGO, Virgo, and KAGRA. We present results of the diagnostic checks done to verify the time-stamping for individual gravitational wave events observed during O3 as well as the timing system performance for all of O3 in LIGO Livingston and LIGO Hanford. We find that, after 3 observing runs, the LIGO timing system continues to reliably meet mission requirements of timing precision below 1 $\mu$s with a significant safety margin.

Read this paper on arXiv…

A. Sullivan, Y. Asali, Z. Márka, et. al.
Tue, 4 Apr 23
28/111

Comments: 11 pages, 8 figures

Towards 3D Retrieval of Exoplanet Atmospheres: Assessing Thermochemical Equilibrium Estimation Methods [EPA]

Posted on by

http://arxiv.org/abs/2304.00073


Characterizing exoplanetary atmospheres via Bayesian retrievals requires assuming some chemistry model, such as thermochemical equilibrium or parameterized abundances. The higher-resolution data offered by upcoming telescopes enables more complex chemistry models within retrieval frameworks. Yet, many chemistry codes that model more complex processes like photochemistry and vertical transport are computationally expensive, and directly incorporating them into a 1D retrieval model can result in prohibitively long execution times. Additionally, phase-curve observations with upcoming telescopes motivate 2D and 3D retrieval models, further exacerbating the lengthy runtime for retrieval frameworks with complex chemistry models. Here, we compare thermochemical equilibrium approximation methods based on their speed and accuracy with respect to a Gibbs energy-minimization code. We find that, while all methods offer orders of magnitude reductions in computational cost, neural network surrogate models perform more accurately than the other approaches considered, achieving a median absolute dex error <0.03 for the phase space considered. While our results are based on a 1D chemistry model, our study suggests that higher dimensional chemistry models could be incorporated into retrieval models via this surrogate modeling approach.

Read this paper on arXiv…

M. Himes, J. Harrington and A. Baydin
Tue, 4 Apr 23
31/111

Comments: 22 pages, 14 figures, submitted to PSJ 2022/11/22, revised 2023/3/7, accepted 2023/3/23

Fabrication Development for SPT-SLIM, a Superconducting Spectrometer for Line Intensity Mapping [IMA]

Posted on by

http://arxiv.org/abs/2304.00973


Line Intensity Mapping (LIM) is a new observational technique that uses low-resolution observations of line emission to efficiently trace the large-scale structure of the Universe out to high redshift. Common mm/sub-mm emission lines are accessible from ground-based observatories, and the requirements on the detectors for LIM at mm-wavelengths are well matched to the capabilities of large-format arrays of superconducting sensors. We describe the development of an R = 300 on-chip superconducting filter-bank spectrometer covering the 120–180 GHz band optimized for future mm-LIM experiments, focusing on SPT-SLIM, a pathfinder LIM instrument for the South Pole Telescope. Radiation is coupled from the telescope optical system to the spectrometer chip via an array of feedhorn-coupled orthomode transducers. Superconducting microstrip transmission lines then carry the signal to an array of channelizing half-wavelength resonators, and the output of each spectral channel is sensed by a lumped element kinetic inductance detector (leKID). Key areas of development include incorporating new low-loss dielectrics to improve both the achievable spectral resolution and optical efficiency and development of a robust fabrication process to create a galvanic connection between ultra-pure superconducting thin-films to realize multi-material (hybrid) leKIDs. We provide an overview of the spectrometer design, fabrication process, and prototype devices.

Read this paper on arXiv…

T. Cecil, C. Albert, A. Anderson, et. al.
Tue, 4 Apr 23
44/111

Comments: 7 pages, 7 figures, presented at 2022 Applied Superconductivity Conference

Reproducing the results for NICER observation of PSR J0030+0451 [HEAP]

Posted on by

http://arxiv.org/abs/2304.01035


NASA’s Neutron Star Interior Composition Explorer (NICER) observed X-ray emission from the pulsar PSR J0030+0451 in 2018. Riley \textit{et al.} reported Bayesian parameter measurements of the mass and the radius of the star using pulse-profile modeling of the X-ray data. In this paper, we reproduce their result using the open-source software \textit{X-PSI} and the publicly available data. We reproduce the main result within the expected statistical error. We note the challenges we faced in reproducing the results. We demonstrate that not only that the analysis can be reproduced, it can also be reused in future works by changing the prior distribution for the radius, and by changing the sampler configuration. We find no significant change in the measurement of the mass and radius, demonstrating that the original result is robust to these changes. Finally, we provide a containerized working environment that facilitates third-party reproduction of the measurements of mass and radius of PSR J0030+0451 using the NICER observations.

Read this paper on arXiv…

C. Afle, P. Miles, S. Caino-Lores, et. al.
Tue, 4 Apr 23
49/111

Comments: 12 pages, 4 figures, 2 tables

Characterization of MKIDs for CMB observation at 220 GHz with the South Pole Telescope [IMA]

Posted on by

http://arxiv.org/abs/2304.01158


We present an updated design of the 220 GHz microwave kinetic inductance detector (MKID) pixel for SPT-3G+, the next-generation camera for the South Pole Telescope. We show results of the dark testing of a 63-pixel array with mean inductor quality factor $Q_i = 4.8 \times 10^5$, aluminum inductor transition temperature $T_c = 1.19$ K, and kinetic inductance fraction $\alpha_k = 0.32$. We optically characterize both the microstrip-coupled and CPW-coupled resonators, and find both have a spectral response close to prediction with an optical efficiency of $\eta \sim 70\%$. However, we find slightly lower optical response on the lower edge of the band than predicted, with neighboring dark detectors showing more response in this region, though at level consistent with less than 5\% frequency shift relative to the optical detectors. The detectors show polarized response consistent with expectations, with a cross-polar response of $\sim 10\%$ for both detector orientations.

Read this paper on arXiv…

K. Dibert, P. Barry, A. Anderson, et. al.
Tue, 4 Apr 23
50/111

Comments: 6 pages, 5 figures, ASC 2022 proceedings

Measurement of Dielectric Loss in Silicon Nitride at Centimeter and Millimeter Wavelengths [IMA]

Posted on by

http://arxiv.org/abs/2304.01103


This work presents a suite of measurement techniques for characterizing the dielectric loss tangent across a wide frequency range from $\sim$1 GHz to 150 GHz using the same test chip. In the first method, we fit data from a microwave resonator at different temperatures to a model that captures the two-level system (TLS) response to extract and characterize both the real and imaginary components of the dielectric loss. The inverse of the internal quality factor is a second measure of the overall loss of the resonator, where TLS loss through the dielectric material is typically the dominant source. The third technique is a differential optical measurement at 150 GHz. The same antenna feeds two microstrip lines with different lengths that terminate in two microwave kinetic inductance detectors (MKIDs). The difference in the detector response is used to estimate the loss per unit length of the microstrip line. Our results suggest a larger loss for SiN$_x$ at 150 GHz of ${\mathrm{\tan \delta\sim 4\times10^{-3}}}$ compared to ${\mathrm{2.0\times10^{-3}}}$ and ${\mathrm{\gtrsim 1\times10^{-3}}}$ measured at $\sim$1 GHz using the other two methods. {These measurement techniques can be applied to other dielectrics by adjusting the microstrip lengths to provide enough optical efficiency contrast and other mm/sub-mm frequency ranges by tuning the antenna and feedhorn accordingly.

Read this paper on arXiv…

Z. Pan, P. Barry, T. Cecil, et. al.
Tue, 4 Apr 23
62/111

Comments: N/A

Electromagnetic Properties of Aluminum-based Bilayers for Kinetic Inductance Detectors [IMA]

Posted on by

http://arxiv.org/abs/2304.00431


The complex conductivity of a superconducting thin film is related to the quasiparticle density, which depends on the physical temperature and can also be modified by external pair breaking with photons and phonons. This relationship forms the underlying operating principle of Kinetic Inductance Detectors (KIDs), where the detection threshold is governed by the superconducting energy gap. We investigate the electromagnetic properties of thin-film aluminum that is proximitized with either a normal metal layer of copper or a superconducting layer with a lower $T_C$, such as iridium, in order to extend the operating range of KIDs. Using the Usadel equations along with the Nam expressions for complex conductivity, we calculate the density of states and the complex conductivity of the resulting bilayers to understand the dependence of the pair breaking threshold, surface impedance, and intrinsic quality factor of superconducting bilayers on the relative film thicknesses. The calculations and analyses provide theoretical insights in designing aluminum-based bilayer kinetic inductance detectors for detection of microwave photons and athermal phonons at the frequencies well below the pair breaking threshold of a pure aluminum film.

Read this paper on arXiv…

G. Wang, P. Barry, T. Cecil, et. al.
Tue, 4 Apr 23
65/111

Comments: Submitted as a proceeding for Applied Superconductivity Conference 2022

Noise Optimization for MKIDs with Different Design Geometries and Material Selections [IMA]

Posted on by

http://arxiv.org/abs/2304.01133


The separation and optimization of noise components is critical to microwave-kinetic inductance detector (MKID) development. We analyze the effect of several changes to the lumped-element inductor and interdigitated capacitor geometry on the noise performance of a series of MKIDs intended for millimeter-wavelength experiments. We extract the contributions from two-level system noise in the dielectric layer, the generation-recombination noise intrinsic to the superconducting thin-film, and system white noise from each detector noise power spectrum and characterize how these noise components depend on detector geometry, material, and measurement conditions such as driving power and temperature. We observe a reduction in the amplitude of two-level system noise with both an elevated sample temperature and an increased gap between the fingers within the interdigitated capacitors for both aluminum and niobium detectors. We also verify the expected reduction of the generation-recombination noise and associated quasiparticle lifetime with reduced inductor volume. This study also iterates over different materials, including aluminum, niobium, and aluminum manganese, and compares the results with an underlying physical model.

Read this paper on arXiv…

Z. Pan, K. Dibert, J. Zhang, et. al.
Tue, 4 Apr 23
67/111

Comments: N/A

Quasiparticle Generation-Recombination Noise in the Limit of Low Detector Volume [IMA]

Posted on by

http://arxiv.org/abs/2304.01156


We have measured the quasiparticle generation-recombination (GR) noise in aluminium lumped element kinetic inductors with a wide range of detector volumes at various temperatures. The basic detector consists of meandering inductor and interdigitated capacitor fingers. The inductor volume is varied from 2 to 153 {\mu}m^{3} by changing the inductor width and length to maintain a constant inductance. We started with measuring the power spectrum density (PSD) of the detectors frequency noise which is a function of GR noise and we clearly observed the spectrum roll off at 10 kHz which corresponds to the quasiparticle lifetime. Using data from a temperature sweep of the resonator frequency we convert the frequency fluctuation to quasiparticle fluctuation and observe its strong dependence on detector volume: detectors with smaller volume display less quasiparticle noise amplitude. Meanwhile we observe a saturated quasiparticle density at low temperature from all detectors as the quasiparticle life time {\tau}qp approaches a constant value at low temperature.

Read this paper on arXiv…

J. Li, P. Barry, T. Cecil, et. al.
Tue, 4 Apr 23
73/111

Comments: N/A

TIRCAM2 Camera Interface on the Side port of the 3.6 meter Devasthal Optical Telescope [IMA]

Posted on by

http://arxiv.org/abs/2304.00243


The TIFR Near Infrared Imaging Camera-II (TIRCAM2) is being used at the 3.6 m Devasthal Optical Telescope (DOT) operated by Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, Uttarakhand, India. Earlier, the TIRCAM2 was used at the main port of the DOT on time shared basis. It has now been installed at the side port of the telescope. Side port installation allows near simultaneous observations with the main port instrument as well as longer operating periods. Thus, the TIRCAM2 serves the astronomical community for a variety of observations ranging from lunar occultations, transient events and normal scheduled observations.

Read this paper on arXiv…

S. Bhagat, M. Naik, S. Poojary, et. al.
Tue, 4 Apr 23
81/111

Comments: Accepted for publication in the Journal of Astrophysics and Astronomy

Characteristic Modes Analysis of Mutually Coupled Log-Periodic Dipole Antennas [IMA]

Posted on by

http://arxiv.org/abs/2304.00332


Characteristic Modes Analysis (CMA) is a widely used method with recent progress in multi-antenna systems. We employ this method to characterize the mutual coupling phenomenon between two SKALA4.1 antennas, the low-frequency array elements of the future radiotelescope Square Kilometer Array (SKA-Low). The CMA accuracy is first validated at the lowest frequency range of interest with respect to a standard Method of Moments (MoM) solution by decomposing the single antenna into its characteristic modes. We then examine critical frequencies of a two-antenna system in modal decomposition, and characterize those responsible for the radiated electric field spurious spectral features owing to the mutual coupling. We connect these modes to first-order coupling of single antenna CMA modes, by using the eigenvalue data of both single- and two- antenna simulations.

Read this paper on arXiv…

G. Kyriakou, P. Bolli and G. Virone
Tue, 4 Apr 23
84/111

Comments: 4 pages, 5 figures, presented at the 17th European Conference on Antennas and Propagation

Performance of the MALTA Telescope [CL]

Posted on by

http://arxiv.org/abs/2304.01104


MALTA is part of the Depleted Monolithic Active Pixel sensors designed in Tower 180nm CMOS imaging technology. A custom telescope with six MALTA planes has been developed for test beam campaigns at SPS, CERN, with the ability to host several devices under test. The telescope system has a dedicated custom readout, online monitoring integrated into DAQ with realtime hit map, time distribution and event hit multiplicity. It hosts a dedicated fully configurable trigger system enabling to trigger on coincidence between telescope planes and timing reference from a scintillator. The excellent time resolution performance allows for fast track reconstruction, due to the possibility to retain a low hit multiplicity per event which reduces the combinatorics. This paper reviews the architecture of the system and its performance during the 2021 and 2022 test beam campaign at the SPS North Area.

Read this paper on arXiv…

M. Rijnbach, G. Gustavino, P. Allport, et. al.
Tue, 4 Apr 23
85/111

Comments: N/A

Nuevas estrategias de enseñanza: unidades didácticas basadas en temas de la Astronomía Cultural [CL]

Posted on by

http://arxiv.org/abs/2304.01131


One of the main difficulties that students have in learning astronomy topics is that they fail to relate theoretical information with what they experience in the world around them. The construction by students of a conceptual framework in accordance with the astronomical scientific model demands changes in the current teaching approach. Within this framework, Cultural Astronomy (CA) is a discipline that we can use to rethink new didactic strategies. This paper presents two contextualized proposals from CA. In the first one, the teaching of space and time concepts is approached through traditional examples of orientation by the stars and the use of the calendar, using the case of historical ocean navigation without advanced instruments already highlighted in ethnoastronomical studies. In the second, these concepts are worked on from a case study, this time archaeoastronomical: the monumental horizon calendar of the Chankillo archaeological site, and then continue with the local identification of horizon markers that allow students to build their own calendars. The aim is to illustrate ways of introducing CA elements in didactic units that have as one of their main objectives that the students manage to establish correspondences between constructions of the micro to the mega-space that surrounds them.

Read this paper on arXiv…

F. Karaseur, J. Bastero, S. Garofalo, et. al.
Tue, 4 Apr 23
86/111

Comments: Article in Spanish. Published version available at this http URL

The CARMENES search for exoplanets around M dwarfs — A deep transfer learning method to determine Teff and [M/H] of target stars [SSA]

Posted on by

http://arxiv.org/abs/2304.00224


The large amounts of astrophysical data being provided by existing and future instrumentation require efficient and fast analysis tools. Transfer learning is a new technique promising higher accuracy in the derived data products, with information from one domain being transferred to improve the accuracy of a neural network model in another domain. In this work, we demonstrate the feasibility of applying the deep transfer learning (DTL) approach to high-resolution spectra in the framework of photospheric stellar parameter determination. To this end, we used 14 stars of the CARMENES survey sample with interferometric angular diameters to calculate the effective temperature, as well as six M dwarfs that are common proper motion companions to FGK-type primaries with known metallicity. After training a deep learning (DL) neural network model on synthetic PHOENIX-ACES spectra, we used the internal feature representations together with those 14+6 stars with independent parameter measurements as a new input for the transfer process. We compare the derived stellar parameters of a small sample of M dwarfs kept out of the training phase with results from other methods in the literature. Assuming that temperatures from bolometric luminosities and interferometric radii and metallicities from FGK+M binaries are sufficiently accurate, DTL provides a higher accuracy than our previous state-of-the-art DL method (mean absolute differences improve by 20 K for temperature and 0.2 dex for metallicity from DL to DTL when compared with reference values from interferometry and FGK+M binaries). Furthermore, the machine learning (internal) precision of DTL also improves as uncertainties are five times smaller on average. These results indicate that DTL is a robust tool for obtaining M-dwarf stellar parameters comparable to those obtained from independent estimations for well-known stars.

Read this paper on arXiv…

A. Bello-García, V. Passegger, J. Ordieres-Meré, et. al.
Tue, 4 Apr 23
89/111

Comments: N/A

Predictive power of daily viscacha and vicuña sightings on Simons Array site work results [IMA]

Posted on by

http://arxiv.org/abs/2304.00351


We studied the predictive power of daily animal sightings on site work outcomes at the Polarbear and Simons Array experiment site in the Atacama Desert, Chile. Specifically, we observed the number of viscacha and vicuna sightings during a two-month period, totaling 31 observation days, and analyzed their relationship with site work outcomes using machine learning techniques. Our results show that there was no significant correlation between the number of animal sightings and site work outcomes. The feather importance score for viscacha and vicuna were 0.71068 and 0.057762, respectively. Future research may include expanding the analysis to include other animal species, investigating the impact of human activity on site work outcomes, and exploring alternative machine learning models or statistical techniques.

Read this paper on arXiv…

P. Siritanasak, I. Birdwell, L. Lowry, et. al.
Tue, 4 Apr 23
93/111

Comments: N/A

An Astronomers Guide to Machine Learning [IMA]

Posted on by

http://arxiv.org/abs/2304.00512


With the volume and availability of astronomical data growing rapidly, astronomers will soon rely on the use of machine learning algorithms in their daily work. This proceeding aims to give an overview of what machine learning is and delve into the many different types of learning algorithms and examine two astronomical use cases. Machine learning has opened a world of possibilities for us astronomers working with large amounts of data, however if not careful, users can trip into common pitfalls. Here we’ll focus on solving problems related to time-series light curve data and optical imaging data mainly from the Deeper, Wider, Faster Program (DWF). Alongside the written examples, online notebooks will be provided to demonstrate these different techniques. This guide aims to help you build a small toolkit of knowledge and tools to take back with you for use on your own future machine learning projects.

Read this paper on arXiv…

S. Webb and S. Goode
Tue, 4 Apr 23
99/111

Comments: 12 pages, 5 Figures, International Astronomical Union Proceedings Series 368

A Long-Baseline Atom Interferometer at CERN: Conceptual Feasibility Study [CL]

Posted on by

http://arxiv.org/abs/2304.00614


We present results from exploratory studies, supported by the Physics Beyond Colliders (PBC) Study Group, of the suitability of a CERN site and its infrastructure for hosting a vertical atom interferometer (AI) with a baseline of about 100 m. We first review the scientific motivations for such an experiment to search for ultralight dark matter and measure gravitational waves, and then outline the general technical requirements for such an atom interferometer, using the AION-100 project as an example. We present a possible CERN site in the PX46 access shaft to the Large Hadron Collider (LHC), including the motivations for this choice and a description of its infrastructure. We then assess its compliance with the technical requirements of such an experiment and what upgrades may be needed. We analyse issues related to the proximity of the LHC machine and its ancillary hardware and present a preliminary safety analysis and the required mitigation measures and infrastructure modifications. In conclusion, we identify primary cost drivers and describe constraints on the experimental installation and operation schedules arising from LHC operation. We find no technical obstacles: the CERN site is a very promising location for an AI experiment with a vertical baseline of about 100 m.

Read this paper on arXiv…

G. Arduini, L. Badurina, K. Balazs, et. al.
Tue, 4 Apr 23
100/111

Comments: 51 pages, 39 figures, version with higher resolution figures available from this https URL

Detecting cosmic voids via maps of geometric-optics parameters [CEA]

Posted on by

http://arxiv.org/abs/2304.00591


Curved-spacetime geometric-optics maps derived from a deep photometric survey should contain information about the three-dimensional matter distribution and thus about cosmic voids in the survey, despite projection effects. We explore to what degree sky-plane geometric-optics maps can reveal the presence of intrinsic three-dimensional voids. We carry out a cosmological $N$-body simulation and place it further than a gigaparsec from the observer, at redshift 0.5. We infer three-dimensional void structures using the watershed algorithm. Independently, we calculate a surface overdensity map and maps of weak gravitational lensing and geometric-optics scalars. We propose and implement a heuristic algorithm for detecting (projected) radial void profiles from these maps. We find in our simulation that given the sky-plane centres of the three-dimensional watershed-detected voids, there is significant evidence of correlated void centres in the surface overdensity $\Sigma$, the averaged weak-lensing tangential shear $\overline{\gamma_\perp}$, the Sachs expansion $\theta$, and the Sachs shear modulus $\lvert\sigma\rvert$. Recovering the centres of the three-dimensional voids from the sky-plane information alone is significant given the weak-lensing shear $\overline{\gamma_\perp}$, the Sachs expansion $\theta$, or the Sachs shear $\lvert\sigma\rvert$, but not significant for the surface overdensity $\Sigma$. Void radii are uncorrelated between three-dimensional and two-dimensional voids; our algorithm is not designed to distinguish voids that are nearly concentric in projection. This investigation shows preliminary evidence encouraging observational studies of gravitational lensing through individual voids, either blind or with spectroscopic/photometric redshifts. The former case – blind searches – should generate falsifiable predictions of intrinsic three-dimensional void centres.

Read this paper on arXiv…

M. Peper, B. Roukema and K. Bolejko
Tue, 4 Apr 23
101/111

Comments: 14 pages, 8 figures, 3 tables, zenodo.7792910 at this https URL, archived git at this https URL, live git at this https URL

Minute-Cadence Observations of the LAMOST Fields with the TMTS: II. Catalogues of Short-Period Variable Stars from the First Two-Year Surveys [SSA]

Posted on by

http://arxiv.org/abs/2303.18050


Over the past few years, wide-field time-domain surveys like ZTF and OGLE have led to discoveries of various types of interesting short-period stellar variables, such as ultracompact eclipsing binary white dwarfs, rapidly rotating magnetised white dwarfs (WDs), transitional cataclysmic variables between hydrogen-rich and helium accretion, and blue large-amplitude pulsators (BLAPs), which greatly enrich our understandings of stellar physics under some extreme conditions. In this paper, we report the first-two-year discoveries of short-period variables (i.e., P<2 hr) by the Tsinghua University-Ma Huateng Telescopes for Survey (TMTS). TMTS is a multi-tube telescope system with a field of view up to 18 deg^2, which started to monitor the LAMOST sky areas since 2020 and generated uninterrupted minute-cadence light curves for about ten million sources within 2 years. Adopting the Lomb-Scargle periodogram with period-dependent thresholds for the maximum powers, we identify over 1 100 sources that exhibit a variation period shorter than 2 hr. Compiling the light curves with the Gaia magnitudes and colours, LAMOST spectral parameters, VSX classifications, and archived observations from other prevailing time-domain survey missions, we identified 1 076 as delta Scuti stars, which allows us study their populations and physical properties in the short-period regime. The other 31 sources include BLAPs, subdwarf B variables (sdBVs), pulsating WDs, ultracompact/short-period eclipsing/ellipsoidal binaries, cataclysmic variables below the period gap, etc., which are highly interesting and worthy of follow-up investigations.

Read this paper on arXiv…

J. Lin, X. Wang, J. Mo, et. al.
Mon, 3 Apr 23
4/53

Comments: 22 pages, 15 figures, 5 tables, accepted by MNRAS

ronswanson: Building Table Models for 3ML [IMA]

Posted on by

http://arxiv.org/abs/2303.17609


ronswanson provides a simple-to-use framework for building so-called table or template models for astromodelsthe modeling package for multi-messenger astrophysical data-analysis framework, 3ML. With astromodels and 3ML one can build the interpolation table of a physical model result of an expensive computer simulation. This then enables efficient reevaluation of the model while, for example, fitting it to a dataset. While 3ML and astromodels provide factories for building table models, the construction of pipelines for models that must be run on high-performance computing (HPC) systems can be cumbersome. ronswanson removes this complexity with a simple, reproducible templating system. Users can easily prototype their pipeline on multi-core workstations and then switch to a multi-node HPC system. ronswanson automatically generates the required Python and SLURM scripts to scale the execution of 3ML with astromodel‘s table models on an HPC system.

Read this paper on arXiv…

J. Burgess
Mon, 3 Apr 23
10/53

Comments: 3 pages. Accepted for publication in JOSS

Programmed but Arbitrary Control Minimization of Amplitude and phase for speckle Nulling (PACMAN) [IMA]

Posted on by

http://arxiv.org/abs/2303.18231


We revive a cross-platform focal-plane wavefront sensing and control algorithm originally released in 1980 and show that it can provide significant contrast improvements over conventional control methods on coronagraphic instruments. Its simplicity makes it applicable to various coronagraph models and we demonstrate it on a classical Lyot coronagraph and a phase-apodized pupil Lyot coronagraph, both in simulation and in laboratory experiments. Surprisingly, it had been forgotten for decades, but we present its unbeatable advantages considering the increase in computational power in the last 40 years. We consider it a major game changer in the planning for future, space-based high-contrast imaging missions and recommend it be intensively revisited by all readers.

Read this paper on arXiv…

I. Laginja and R. Pourcelot
Mon, 3 Apr 23
14/53

Comments: Intended for public access on 1 April 2023

Boosting Line Intensity Map Signal-to-Noise with the Ly-$α$ Forest Cross-Correlation [CEA]

Posted on by

http://arxiv.org/abs/2303.17632


We forecast the prospects for cross-correlating future line intensity mapping (LIM) surveys with the current and future Ly-$\alpha$ forest data. We use large cosmological hydrodynamic simulations to model the expected emission signal for the CO rotational transition in the COMAP LIM experiment at the 5-year benchmark and the Ly-$\alpha$ forest absorption signal for various surveys, including eBOSS, DESI, and PFS. We show that CO$\times$Ly-$\alpha$ forest can significantly enhance the detection signal-to-noise ratio of CO, with a $200$ to $300 \%$ improvement when cross-correlated with the forest observed in the Prime Focus Spectrograph (PFS) survey and a $50$ to $75\%$ enhancement for the currently available eBOSS or the upcoming DESI observations. We compare to the signal-to-noise improvements expected for a galaxy survey and show that CO$\times$Ly-$\alpha$ is competitive with even a spectroscopic galaxy survey in raw signal-to-noise. Furthermore, our study suggests that the clustering of CO emission is tightly constrained by CO$\times$Ly-$\alpha$ forest, due to the increased signal-to-noise ratio and the simplicity of Ly-$\alpha$ absorption power spectrum modeling. Any foreground contamination or systematics are expected not to be shared between LIM surveys and Ly-$\alpha$ forest observations; this provides an unbiased inference. Our findings highlight the potential benefits of utilizing the Ly-$\alpha$ forest to aid in the initial detection of signals in line intensity experiments. For example, we also estimate that [CII]$\times$Ly-$\alpha$ forest measurements from EXCLAIM and DESI/eBOSS, respectively, should have a larger signal-to-noise ratio than planned [CII]$\times$quasar observations by about an order of magnitude. Our results can be readily applied to actual data thanks to the observed quasar spectra in eBOSS Stripe 82, which overlaps with several LIM surveys.

Read this paper on arXiv…

M. Qezlou, S. Bird, A. Lidz, et. al.
Mon, 3 Apr 23
17/53

Comments: Codes and the produced data are available at this https URL

Sodium Brightening of (3200) Phaethon Near Perihelion [EPA]

Posted on by

http://arxiv.org/abs/2303.17625


Sunskirting asteroid (3200) Phaethon has been repeatedly observed in STEREO HI1 imagery to anomalously brighten and produce an antisunward tail for a few days near each perihelion passage, phenomena previously attributed to the ejection of micron-sized dust grains. Color imaging by the SOHO LASCO coronagraphs during the 2022 May apparition indicate that the observed brightening and tail development instead capture the release of sodium atoms, which resonantly fluoresce at the 589.0/589.6 nm D lines. While HI1’s design bandpass nominally excludes the D lines, filter degradation has substantially increased its D line sensitivity, as quantified by the brightness of Mercury’s sodium tail in HI1 imagery. Furthermore, the expected fluorescence efficiency and acceleration of sodium atoms under solar radiation readily reproduce both the photometric and morphological behaviors observed by LASCO and HI1 during the 2022 apparition and the 17 earlier apparitions since 1997. This finding connects Phaethon to the broader population of sunskirting and sungrazing comets observed by SOHO, which often also exhibit bright sodium emission with minimal visible dust, but distinguishes it from other sunskirting asteroids without detectable sodium production under comparable solar heating. These differences may reflect variations in the degree of sodium depletion of near-surface material, and thus the extent and/or timing of any past or present resurfacing activity.

Read this paper on arXiv…

Q. Zhang, K. Battams, Q. Ye, et. al.
Mon, 3 Apr 23
21/53

Comments: 30 pages, 14 figures, 6 tables; PSJ, in press

Protoplanet Express, a video game based on numerical simulations [CL]

Posted on by

http://arxiv.org/abs/2303.17654


Astronomical images can be fascinating to the general public, but the interaction is typically limited to contemplation. Numerical simulations of astronomical systems do permit a closer interaction, but are generally unknown outside the research community. We are developing “Protoplanet Express”, a video game based on hydrodynamical simulations of protoplanetary discs. In the game, the player visits several discs, finds its relevant features and learns about them. Here we present the current version of the game, discuss its reception, and consider its further development.

Read this paper on arXiv…

J. Cuadra, M. Vergara, B. Escárate, et. al.
Mon, 3 Apr 23
40/53

Comments: 6 pages, 4 figures, submitted to the Proceedings of ASP 2022. Beta version of game available at this https URL

ChatGPT scores a bad birdie in counting gravitational-wave chirps [HEAP]

Posted on by

http://arxiv.org/abs/2303.17628


How many gravitational-wave observations from compact object mergers have we seen to date? This seemingly simple question has a surprisingly complex answer that even ChatGPT struggles to answer. To shed light on this, we present a database with the literature’s answers to this question. We find values spanning 67-100 for the number of detections from double compact object mergers to date, emphasizing that the exact number of detections is uncertain and depends on the chosen data analysis pipeline and underlying assumptions. We also review the number of gravitational-wave detections expected in the coming decades with future observing runs, finding values up to millions of detections per year in the era of Cosmic Explorer and Einstein Telescope. We present a publicly available code to visualize the detection numbers, highlighting the exponential growth in gravitational-wave observations in the coming decades and the exciting prospects of gravitational-wave astrophysics. See this http URL We plan to keep this database up-to-date and welcome comments and suggestions for additional references.

Read this paper on arXiv…

F. Broekgaarden
Mon, 3 Apr 23
52/53

Comments: 1 April submission, with fun videos for visualizing the landscape of gravitational waves! (they are awesome!) See this http URL

On the computation of interstellar extinction in photoionized nebulae [GA]

Posted on by

http://arxiv.org/abs/2303.17067


Ueta & Otsuka (2021) proposed a method, named as the “Proper Plasma Analysis Practice”, to analyze spectroscopic data of ionized nebulae. The method is based on a coherent and simultaneous determination of the reddening correction and physical conditions in the nebulae. The same authors (Ueta & Otsuka 2022, UO22) reanalyzed the results of Galera-Rosillo et al. (2022, GR22) on nine of the brightest planetary nebulae in M31. They claim that, if standard values of the physical conditions are used to compute the extinction instead of their proposed method, extinction correction is underestimated by more than 50% and hence, ionic and elemental abundance determinations, especially the N/O ratio, are incorrect. Several tests were performed to assess the accuracy of the results of GR22, when determining: i) the extinction coefficient, ii) the electron temperature and density, and iii) the ionic abundances. In the latter case, N+ /H+ ionic abundance was recalculated using both H_alpha and H_beta as the reference H I emissivity. The analysis shows that the errors introduced by adopting standard values of the plasma conditions by GR22 are small, within their quoted uncertainties. On the other hand, the interstellar extinction in UO22 is found to be overestimated for five of the nine nebulae considered. This propagates into their analysis of the properties of the nebulae and their progenitors. The python notebook used to generate all the results presented in this paper are of public access on a Github repository. The results from GR22 are proven valid and the conclusions of the paper hold firmly. Although the PPAP is, in principle, a recommended practice, we insist that it is equally important to critically assess which H I lines are to be included in the determination of the interstellar extinction coefficient, and to assert that physical results are obtained for the undereddened line ratios.

Read this paper on arXiv…

C. Morisset, R. Corradi, J. García-Rojas, et. al.
Fri, 31 Mar 23
3/70

Comments: Accepted for publication in A&A Letter

Processing System for Coherent Dedispersion of Pulsar Radio Emission [IMA]

Posted on by

http://arxiv.org/abs/2303.17280


The work describes a system for converting VLBI observation data using the algorithms of coherent dedispersion and compensation of two-bit signal sampling. Coherent dedispersion is important for processing pulsar observations to obtain the best temporal resolution, while correction for signal sampling makes it possible to get rid of a number of parasitic effects that interfere with the analysis of the diffraction pattern of pulsars. A pipeline has been established that uses the developed converter and the ASC Software Correlator, which will allow reprocessing all archived data of Radioastron pulsar observations and to conduct a search for giant pulses, which requires the best temporal resolution.

Read this paper on arXiv…

G. A., L. F., A. S., et. al.
Fri, 31 Mar 23
4/70

Comments: 16 pages, 4 figures

A search technique to observe precessing compact binary mergers in the advanced detector era [CL]

Posted on by

http://arxiv.org/abs/2303.17364


Gravitational-wave signals from compact binary coalescences are most efficiently identified through matched filter searches, which match the data against a pre-generated bank of gravitational-wave templates. Although different techniques for performing the matched filter, as well as generating the template bank, exist, currently all modelled gravitational-wave searches use templates that restrict the component spins to be aligned (or anti-aligned) with the orbital angular momentum. This means that current searches are less sensitive to gravitational-wave signals generated from binaries with generic spins (precessing), suggesting that, potentially, a significant fraction of signals may remain undetected. In this work we introduce a matched filter search that is sensitive to signals generated from precessing binaries and can realistically be used during a gravitational-wave observing run. We take advantage of the fact that a gravitational-wave signal from a precessing binary can be decomposed into a power series of five harmonics, to show that a generic-spin template bank, which is only $\sim 3\times$ larger than existing aligned-spin banks, is needed to increase our sensitive volume by $\sim 100\%$ for neutron star black hole binaries with total mass larger than $17.5\, M_{\odot}$ and in-plane spins $>0.67$. In fact, our generic spin search performs as well as existing aligned-spin searches for neutron star black hole signals with insignificant in-plane spins, but improves sensitivity by $\sim60\%$ on average across the full generic spin parameter space. We anticipate that this improved technique will identify significantly more gravitational-wave signals, and, ultimately, help shed light on the unknown spin distribution of binaries in the universe.

Read this paper on arXiv…

C. McIsaac, C. Hoy and I. Harry
Fri, 31 Mar 23
30/70

Comments: 23 pages, 12 figures. For data release, see this https URL

As a matter of colon: I am NOT digging cheeky titles (no, but actually yes :>) [IMA]

Posted on by

http://arxiv.org/abs/2303.17059


What’s in a name, a poet once asked. To which we present this work, where we investigate the importance of a paper title in ensuring its best outcome. We queried astronomy papers using NASA ADS and ranked 6000 of them in terms of cheekiness level. We investigate the correlation between citation counts and (i) the presence of a colon, and (ii) cheekiness ranking. We conclude that colon matters in the anatomy of a paper title. So does trying to be cheeky, but we find that too much cheekiness can lead to cringefests. Striking the right balance is therefore crucial. May we recommend aiming for a level 4 cheekiness on a scale of 1-5.

Read this paper on arXiv…

J. Tan and T. Suk
Fri, 31 Mar 23
61/70

Comments: 4 pages, 4 figures, 1 meme. Submitted to Acta Prima Aprila

Multi-scale CLEAN in hard X-ray solar imaging [IMA]

Posted on by

http://arxiv.org/abs/2303.16272


Multi-scale deconvolution is an ill-posed inverse problem in imaging, with applications ranging from microscopy, through medical imaging, to astronomical remote sensing. In the case of high-energy space telescopes, multi-scale deconvolution algorithms need to account for the peculiar property of native measurements, which are sparse samples of the Fourier transform of the incoming radiation. The present paper proposes a multi-scale version of CLEAN, which is the most popular iterative deconvolution method in Fourier space imaging. Using synthetic data generated according to a simulated but realistic source configuration, we show that this multi-scale version of CLEAN performs better than the original one in terms of accuracy, photometry, and regularization. Further, the application to a data set measured by the NASA Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) shows the ability of multi-scale CLEAN to reconstruct rather complex topographies, characteristic of a real flaring event.

Read this paper on arXiv…

A. Volpara, M. Piana and A. Massone
Thu, 30 Mar 23
31/66

Comments: N/A

Prospects for localising Planet 9 with a future Uranus mission [EPA]

Posted on by

http://arxiv.org/abs/2303.16830


Past years have seen various publications attempting to explain the apparent clustering features of trans-Neptunian objects, the most popular explanation being an unconfirmed “Planet 9”. The recently proposed Uranus Orbiter and Probe mission by NASA’s Planetary Science and Astrobiology Decadal Survey could offer the opportunity to precisely determine Planet 9’s sky location and mass by carefully monitoring ranging data during the interplanetary cruise. We use Monte Carlo-Markov Chain methods to reconstruct simulated spacecraft trajectories in a simplified solar system model containing Planet 9, providing an estimate of the mission’s localisation capacity depending on sky location, Earth-spacecraft Doppler link noise level and data collection rate. We characterise the noise via the Allan deviation $\sigma_{\rm A}$, scaled to the Cassini-era value $\sigma_{\rm A}^{\rm \scriptscriptstyle Cass} = 3 \times 10^{-15}$, finding that daily measurements of the spacecraft position can lead to $\sim$0.2 deg$^2$ localisation of Planet 9 (assuming $M_9 = 6.3 M_{\oplus}$, $d_9 = 460$AU). As little as a 3-fold improvement in $\sigma_{\rm A}$ drastically decreases the sky localisation area size to $\sim$0.01 deg$^2$. Thus, we showcase that a future Uranus mission carries a significant potential also for non-Uranian science.

Read this paper on arXiv…

J. Bucko, D. Soyuer and L. Zwick
Thu, 30 Mar 23
40/66

Comments: Submitted to MNRAS: Letters, 5 pages, 4 figures

ASSIST: An Ephemeris-Quality Test Particle Integrator [EPA]

Posted on by

http://arxiv.org/abs/2303.16246


We introduce ASSIST, a software package for ephemeris-quality integrations of test particles. ASSIST is an extension of the REBOUND framework and makes use of its IAS15 integrator to integrate test particle trajectories in the field of the Sun, Moon, planets, and 16 massive asteroids, with the positions of the masses coming from the JPL DE441 ephemeris and its associated asteroid perturber file. The package incorporates the most significant gravitational harmonics and general relativistic corrections. ASSIST also accounts for position- and velocity-dependent non-gravitational effects. The first order variational equations are included for all terms to support orbit fitting and covariance mapping. This new framework is meant to provide an open-source package written in a modern language to enable high-precision orbital analysis and science by the small body community. ASSIST is open source, freely distributed under the GNU General Public license, version 3.

Read this paper on arXiv…

M. Holman, A. Akmal, D. Farnocchia, et. al.
Thu, 30 Mar 23
58/66

Comments: Submitted to PSJ (27 January 2023), Revised (28 March 2023)

Dealing with large gaps in asteroseismic time series [IMA]

Posted on by

http://arxiv.org/abs/2303.15584


With long data sets available for asteroseismology from space missions, it is sometimes necessary to deal with time series that have large gaps. This is becoming particularly relevant for TESS, which is revisiting many fields on the sky every two years. Because solar-like oscillators have finite mode lifetimes, it has become tempting to close large gaps by shifting time stamps. Using actual data from the Kepler Mission, we show that this results in artificial structures in the power spectrum that compromise the measurements of mode frequencies and linewidths.

Read this paper on arXiv…

T. Bedding and H. Kjeldsen
Wed, 29 Mar 23
2/73

Comments: published in RNAAS

Bayesian Computation in Astronomy: Novel methods for parallel and gradient-free inference [IMA]

Posted on by

http://arxiv.org/abs/2303.16134


The goal of this thesis is twofold; introduce the fundamentals of Bayesian inference and computation focusing on astronomical and cosmological applications, and present recent advances in probabilistic computational methods developed by the author that aim to facilitate Bayesian data analysis for the next generation of astronomical observations and theoretical models. The first part of this thesis familiarises the reader with the notion of probability and its relevance for science through the prism of Bayesian reasoning, by introducing the key constituents of the theory and discussing its best practices. The second part includes a pedagogical introduction to the principles of Bayesian computation motivated by the geometric characteristics of probability distributions and followed by a detailed exposition of various methods including Markov chain Monte Carlo (MCMC), Sequential Monte Carlo (SMC), and Nested Sampling (NS). Finally, the third part presents two novel computational methods (Ensemble Slice Sampling and Preconditioned Monte Carlo) and their respective software implementations (zeus and pocoMC). [abridged]

Read this paper on arXiv…

M. Karamanis
Wed, 29 Mar 23
4/73

Comments: PhD Thesis, 280 pages

Revisiting Emission-Line Measurement Methods for Narrow-Line Active Galactic Nuclei [GA]

Posted on by

http://arxiv.org/abs/2303.15618


Measuring broad emission-line widths in active galactic nuclei (AGN) is not straightforward owing to the complex nature of flux variability in these systems. Line-width measurements become especially challenging when signal-to-noise is low, profiles are narrower, or spectral resolution is low. We conducted an extensive correlation analysis between emission-line measurements from the optical spectra of Markarian 142 (Mrk 142; a narrow-line Seyfert galaxy) taken with the Gemini North Telescope (Gemini) at a spectral resolution of 185.6+-10.2 km/s and the Lijiang Telescope (LJT) at 695.2+-3.9 km/s to investigate the disparities in the measured broad-line widths from both telescope data. Mrk~142 posed a challenge due to its narrow broad-line profiles, which were severely affected by instrumental broadening in the lower-resolution LJT spectra. We discovered that allowing the narrow-line flux of permitted lines having broad and narrow components to vary during spectral fitting caused a leak in the narrow-line flux to the broad component, resulting in broader broad-line widths in the LJT spectra. Fixing the narrow-line flux ratios constrained the flux leak and yielded the Hydrogen-beta broad-line widths from LJT spectra $\sim$54\% closer to the Gemini Hydrogen-beta widths than with flexible narrow-line ratios. The availability of spectra at different resolutions presented this unique opportunity to inspect how spectral resolution affected emission-line profiles in our data and adopt a unique method to accurately measure broad-line widths. Reconsidering line-measurement methods while studying diverse AGN populations is critical for the success of future reverberation-mapping studies. Based on the technique used in this work, we offer recommendations for measuring line widths in narrow-line AGN.

Read this paper on arXiv…

V. Khatu, S. Gallagher, K. Horne, et. al.
Wed, 29 Mar 23
12/73

Comments: 14 pages, 9 figures, accepted for publication in PASP

Abell 1201: Detection of an Ultramassive Black Hole in a Strong Gravitational Lens [GA]

Posted on by

http://arxiv.org/abs/2303.15514


Supermassive black holes (SMBHs) are a key catalyst of galaxy formation and evolution, leading to an observed correlation between SMBH mass $M_{\rm BH}$ and host galaxy velocity dispersion $\sigma_{\rm e}$. Outside the local Universe, measurements of $M_{\rm BH}$ are usually only possible for SMBHs in an active state: limiting sample size and introducing selection biases. Gravitational lensing makes it possible to measure the mass of non-active SMBHs. We present models of the $z=0.169$ galaxy-scale strong lens Abell~1201. A cD galaxy in a galaxy cluster, it has sufficient `external shear’ that a magnified image of a $z = 0.451$ background galaxy is projected just $\sim 1$ kpc from the galaxy centre. Using multi-band Hubble Space Telescope imaging and the lens modeling software $\texttt{PyAutoLens}$ we reconstruct the distribution of mass along this line of sight. Bayesian model comparison favours a point mass with $M_{\rm BH} = 3.27 \pm 2.12\times10^{10}\,$M${\rm \odot}$ (3$\sigma$ confidence limit); an ultramassive black hole. One model gives a comparable Bayesian evidence without a SMBH, however we argue this model is nonphysical given its base assumptions. This model still provides an upper limit of $M{\rm BH} \leq 5.3 \times 10^{10}\,$M${\rm \odot}$, because a SMBH above this mass deforms the lensed image $\sim 1$ kpc from Abell 1201’s centre. This builds on previous work using central images to place upper limits on $M{\rm BH}$, but is the first to also place a lower limit and without a central image being observed. The success of this method suggests that surveys during the next decade could measure thousands more SMBH masses, and any redshift evolution of the $M_{\rm BH}$–$\sigma_{\rm e}$ relation. Results are available at https://github.com/Jammy2211/autolens_abell_1201.

Read this paper on arXiv…

J. Nightingale, R. Smith, Q. He, et. al.
Wed, 29 Mar 23
32/73

Comments: Accepted in MNRAS, 27 pages, 22 figures

Machine Learning for Observational Cosmology [IMA]

Posted on by

http://arxiv.org/abs/2303.15794


An array of large observational programs using ground-based and space-borne telescopes is planned in the next decade. The forthcoming wide-field sky surveys are expected to deliver a sheer volume of data exceeding an exabyte. Processing the large amount of multiplex astronomical data is technically challenging, and fully automated technologies based on machine learning and artificial intelligence are urgently needed. Maximizing scientific returns from the big data requires community-wide efforts. We summarize recent progress in machine learning applications in observational cosmology. We also address crucial issues in high-performance computing that are needed for the data processing and statistical analysis.

Read this paper on arXiv…

K. Moriwaki, T. Nishimichi and N. Yoshida
Wed, 29 Mar 23
33/73

Comments: 55 pages, 8 figures, submitted to Reports on Progress in Physics

pygwb: Python-based library for gravitational-wave background searches [CL]

Posted on by

http://arxiv.org/abs/2303.15696


The collection of gravitational waves (GWs) that are either too weak or too numerous to be individually resolved is commonly referred to as the gravitational-wave background (GWB). A confident detection and model-driven characterization of such a signal will provide invaluable information about the evolution of the Universe and the population of GW sources within it. We present a new, user-friendly Python–based package for gravitational-wave data analysis to search for an isotropic GWB in ground–based interferometer data. We employ cross-correlation spectra of GW detector pairs to construct an optimal estimator of the Gaussian and isotropic GWB, and Bayesian parameter estimation to constrain GWB models. The modularity and clarity of the code allow for both a shallow learning curve and flexibility in adjusting the analysis to one’s own needs. We describe the individual modules which make up {\tt pygwb}, following the traditional steps of stochastic analyses carried out within the LIGO, Virgo, and KAGRA Collaboration. We then describe the built-in pipeline which combines the different modules and validate it with both mock data and real GW data from the O3 Advanced LIGO and Virgo observing run. We successfully recover all mock data injections and reproduce published results.

Read this paper on arXiv…

A. Renzini, A. Romero-Rodrguez, C. Talbot, et. al.
Wed, 29 Mar 23
36/73

Comments: 32 pages, 14 figures

Euclid preparation. XXXII. A UV-NIR spectral atlas of compact planetary nebulae for wavelength calibration [GA]

Posted on by

http://arxiv.org/abs/2303.15525


The Euclid mission will conduct an extragalactic survey over 15000 deg$^2$ of the extragalactic sky. The spectroscopic channel of the Near-Infrared Spectrometer and Photometer (NISP) has a resolution of $R\sim450$ for its blue and red grisms that collectively cover the $0.93$–$1.89 $\micron;range. NISP will obtain spectroscopic redshifts for $3\times10^7$ galaxies for the experiments on galaxy clustering, baryonic acoustic oscillations, and redshift space distortion. The wavelength calibration must be accurate within $5$\AA to avoid systematics in the redshifts and downstream cosmological parameters. The NISP pre-flight dispersion laws for the grisms were obtained on the ground using a Fabry-Perot etalon. Launch vibrations, zero gravity conditions, and thermal stabilisation may alter these dispersion laws, requiring an in-flight recalibration. To this end, we use the emission lines in the spectra of compact planetary nebulae (PNe), which were selected from a PN data base. To ensure completeness of the PN sample, we developed a novel technique to identify compact and strong line emitters in Gaia spectroscopic data using the Gaia spectra shape coefficients. We obtained VLT/X-SHOOTER spectra from $0.3$ to $2.5$ \micron;for 19 PNe in excellent seeing conditions and a wide slit, mimicking Euclid’s slitless spectroscopy mode but with 10 times higher spectral resolution. Additional observations of one northern PN were obtained in the $0.80$–$1.90$ \micron range with the GMOS and GNIRS instruments at the Gemini North observatory. The collected spectra were combined into an atlas of heliocentric vacuum wavelengths with a joint statistical and systematic accuracy of 0.1 \AA in the optical and 0.3 \AA in the near-infrared. The wavelength atlas and the related 1D and 2D spectra are made publicly available.

Read this paper on arXiv…

E. Collaboration, K. Paterson, M. Schirmer, et. al.
Wed, 29 Mar 23
56/73

Comments: Accepted in A&A

Estimating Stellar Parameters from LAMOST Low-resolution Spectra [SSA]

Posted on by

http://arxiv.org/abs/2303.15690


The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has acquired tens of millions of low-resolution spectra of stars. This paper investigated the parameter estimation problem for these spectra. To this end, we proposed a deep learning model StarGRU network (StarGRUNet). This network was further applied to estimate the stellar atmospheric physical parameters and 13 elemental abundances from LAMOST low-resolution spectra. On the spectra with signal-to-noise ratios greater than or equal to $5$, the estimation precisions are $94$ K and $0.16$ dex on $T_\texttt{eff}$ and $\log \ g$ respectively, $0.07$ dex to $0.10$ dex on [C/H], [Mg/H], [Al/H], [Si/H], [Ca/H], [Ni/H] and [Fe/H], and $0.10$ dex to $0.16$ dex on [O/H], [S/H], [K/H], [Ti/H] and [Mn/H], and $0.18$ dex and $0.22$ dex on [N/H] and [Cr/H] respectively. The model shows advantages over available models and high consistency with high-resolution surveys. We released the estimated catalog computed from about 8.21 million low-resolution spectra in LAMOST DR8, code, trained model, and experimental data for astronomical science exploration and data processing algorithm research respectively.

Read this paper on arXiv…

X. Li and B. Lin
Wed, 29 Mar 23
57/73

Comments: 15 pages, 12 figures, 3 tables, MNRAS

Fishing for Planets: A Comparative Analysis of EPRV Survey Performance in the Presence of Correlated Noise [EPA]

Posted on by

http://arxiv.org/abs/2303.14571


With dedicated exoplanet surveys underway for multiple extreme precision radial velocity (EPRV) instruments, the near-future prospects of RV exoplanet science are promising. These surveys’ generous time allocations are expected to facilitate the discovery of Earth analogs around bright, nearby Sun-like stars. But survey success will depend critically on the choice of observing strategy, which will determine the survey’s ability to mitigate known sources of noise and extract low-amplitude exoplanet signals. Here, we present an analysis of the Fisher information content of simulated EPRV surveys, accounting for the most recent advances in our understanding of stellar variability on both short and long timescales (i.e., oscillations and granulation within individual nights, and activity-induced variations across multiple nights). In this analysis, we capture the correlated nature of stellar variability by parameterizing these signals with Gaussian Process kernels. We describe the underlying simulation framework as well as the physical interpretation of the Fisher information content, and we evaluate the efficacy of EPRV survey strategies that have been presented in the literature. We explore and compare strategies for scheduling observations over various timescales and we make recommendations to optimize survey performance for the detection of Earth-like exoplanets.

Read this paper on arXiv…

A. Gupta and M. Bedell
Tue, 28 Mar 23
4/81

Comments: 24 Pages, 11 Figures

Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants [HEAP]

Posted on by

http://arxiv.org/abs/2303.15007


The local Cosmic Ray (CR) energy spectrum exhibits a spectral softening at energies around 3~PeV. Sources which are capable of accelerating hadrons to such energies are called hadronic PeVatrons. However, hadronic PeVatrons have not yet been firmly identified within the Galaxy. Several source classes, including Galactic Supernova Remnants (SNRs), have been proposed as PeVatron candidates. The potential to search for hadronic PeVatrons with the Cherenkov Telescope Array (CTA) is assessed. The focus is on the usage of very high energy $\gamma$-ray spectral signatures for the identification of PeVatrons. Assuming that SNRs can accelerate CRs up to knee energies, the number of Galactic SNRs which can be identified as PeVatrons with CTA is estimated within a model for the evolution of SNRs. Additionally, the potential of a follow-up observation strategy under moonlight conditions for PeVatron searches is investigated. Statistical methods for the identification of PeVatrons are introduced, and realistic Monte–Carlo simulations of the response of the CTA observatory to the emission spectra from hadronic PeVatrons are performed. Based on simulations of a simplified model for the evolution for SNRs, the detection of a $\gamma$-ray signal from in average 9 Galactic PeVatron SNRs is expected to result from the scan of the Galactic plane with CTA after 10 hours of exposure. CTA is also shown to have excellent potential to confirm these sources as PeVatrons in deep observations with $\mathcal{O}(100)$ hours of exposure per source.

Read this paper on arXiv…

C. Consortium, F. Acero, A. Acharyya, et. al.
Tue, 28 Mar 23
6/81

Comments: 34 pages, 16 figures, Accepted for publication in Astroparticle Physics

Sensitivity to point-like sources of the ALTO atmospheric particle detector array, designed for $\rm 200\,GeV$–$\rm 50\,TeV$ $γ$-ray astronomy [IMA]

Posted on by

http://arxiv.org/abs/2303.15248


In the context of atmospheric shower arrays designed for $\gamma$-ray astronomy and in the context of the ALTO project, we present: a study of the impact of heavier nuclei in the cosmic-ray background on the estimated $\gamma$-ray detection performance on the basis of dedicated Monte Carlo simulations, a method to calculate the sensitivity to a point-like source, and finally the required observation times to reach a firm detection on a list of known point-like sources.

Read this paper on arXiv…

M. Punch, M. Senniappan, Y. Becherini, et. al.
Tue, 28 Mar 23
15/81

Comments: 16 pages, 7 figures, accepted for publication in JHEAP (Journal of High-Energy Astrophysics)

Photometric classification of QSOs from ALHAMBRA survey using random forest [GA]

Posted on by

http://arxiv.org/abs/2303.14567


Context: Given the current big data era in Astronomy, machine learning based methods have being applied over the last years to identify or classify objects like quasars, galaxies and stars from full sky photometric surveys. Aims: Here we systematically evaluate the performance of Random Forests (RF) in classifying quasars using either magnitudes or colours, both from broad and narrow-band filters, as features. Methods: The working data consists of photometry from the ALHAMBRA Gold Catalogue that we cross-matched with the Sloan Digital Sky Survey (SDSS) and with the Million Quasars Catalogue (Milliquas) for objects labelled as quasars, galaxies or stars. A RF classifier is trained and tested to evaluate the effect on final accuracy and precision of varying the free parameters and the effect of using narrow or broad-band magnitudes or colours. Results: Best performances of the classifier yielded global accuracy and quasar precision around 0.9. Varying model free parameters (within reasonable ranges of values) has no significant effects on the final classification. Using colours instead of magnitudes as features results in better performances of the classifier, especially using colours from the ALHAMBRA Survey. Colours that contribute the most to the classification are those containing the near-infrared $JHK$ bands.

Read this paper on arXiv…

B. Arroquia-Cuadros, N. Sanchez, V. Gomez, et. al.
Tue, 28 Mar 23
21/81

Comments: 7 pages including 6 figures and 3 tables. Accepted for publication in Astronomy and Astrophysics

Towards robust corrections for stellar contamination in JWST exoplanet transmission spectra [EPA]

Posted on by

http://arxiv.org/abs/2303.15418


Transmission spectroscopy is still the preferred characterization technique for exoplanet atmospheres, although it presents unique challenges which translate into characterization bottlenecks when robust mitigation strategies are missing. Stellar contamination is one of such challenges that can overpower the planetary signal by up to an order of magnitude, and thus not accounting for stellar contamination can lead to significant biases in the derived atmospheric properties. Yet, accounting for stellar contamination may not be straightforward, as important discrepancies exist between state-of-the-art stellar models and measured spectra and between models themselves. Here we explore the extent to which stellar models can be used to reliably correct for stellar contamination and yield a planet’s uncontaminated transmission spectrum. We find that (1) discrepancies between stellar models can dominate the noise budget of JWST transmission spectra of planets around stars with heterogeneous photospheres; (2) the true number of unique photospheric spectral components and their properties can only be accurately retrieved when the stellar models have a sufficient fidelity; and (3) under such optimistic circumstances the contribution of stellar contamination to the noise budget of a transmission spectrum is considerably below that of the photon noise for the standard transit observation setup. Therefore, we suggest (1) increased efforts towards development of model spectra of stars and their active regions in a data-driven manner; and (2) the development of empirical approaches for deriving spectra of photospheric components using the observatories with which the atmospheric explorations are carried out.

Read this paper on arXiv…

B. Rackham and J. Wit
Tue, 28 Mar 23
24/81

Comments: 15 pages, 8 figures, 2 tables

Applications of Gaussian Processes at Extreme Lengthscales: From Molecules to Black Holes [CL]

Posted on by

http://arxiv.org/abs/2303.14291


In many areas of the observational and experimental sciences data is scarce. Data observation in high-energy astrophysics is disrupted by celestial occlusions and limited telescope time while data derived from laboratory experiments in synthetic chemistry and materials science is time and cost-intensive to collect. On the other hand, knowledge about the data-generation mechanism is often available in the sciences, such as the measurement error of a piece of laboratory apparatus. Both characteristics, small data and knowledge of the underlying physics, make Gaussian processes (GPs) ideal candidates for fitting such datasets. GPs can make predictions with consideration of uncertainty, for example in the virtual screening of molecules and materials, and can also make inferences about incomplete data such as the latent emission signature from a black hole accretion disc. Furthermore, GPs are currently the workhorse model for Bayesian optimisation, a methodology foreseen to be a guide for laboratory experiments in scientific discovery campaigns. The first contribution of this thesis is to use GP modelling to reason about the latent emission signature from the Seyfert galaxy Markarian 335, and by extension, to reason about the applicability of various theoretical models of black hole accretion discs. The second contribution is to extend the GP framework to molecular and chemical reaction representations and to provide an open-source software library to enable the framework to be used by scientists. The third contribution is to leverage GPs to discover novel and performant photoswitch molecules. The fourth contribution is to introduce a Bayesian optimisation scheme capable of modelling aleatoric uncertainty to facilitate the identification of material compositions that possess intrinsic robustness to large scale fabrication processes.

Read this paper on arXiv…

R. Griffiths
Tue, 28 Mar 23
25/81

Comments: PhD Thesis submitted at the University of Cambridge, August 2022. The thesis is based on a number of previous works also available on arXiv (see Introduction)

Detection Rate of <50-meter Interstellar Objects with LSST [IMA]

Posted on by

http://arxiv.org/abs/2303.14766


The previous decade saw the discovery of the first four known interstellar objects due to advances in astronomical viewing equipment. Future sky surveys with greater sensitivity will allow for more frequent detections of such objects, including increasingly small objects. We consider the capabilities of the Legacy Survey of Space and Time (LSST) of the Vera C. Rubin Observatory to detect interstellar objects of small sizes during its period of operation over the next decade. We use LSST’s detection capabilities and simulate populations of interstellar objects in the range of 1-50m in diameter to calculate the expected number of small interstellar objects that will be detected. We use previous detections of interstellar objects to calibrate our object density estimates. We also consider the impact of the population’s albedo on detection rates by considering populations with two separate albedo distributions: a constant albedo of 0.06 and an albedo distribution that resembles near earth asteroids. We find that the number of detections increases with the diameter over the range of diameters we consider. We estimate a detection rate of up to a small ISO every two years of LSST’s operation with an increase by a factor of ten for future surveys that extend a magnitude deeper.

Read this paper on arXiv…

C. Ezell and A. Loeb
Tue, 28 Mar 23
29/81

Comments: 17 pages, 7 figures

Scattering Parameter Measurements of the Long Wavelength Array Antenna and Front End Electronics [IMA]

Posted on by

http://arxiv.org/abs/2303.14904


We present recent 2-port vector network analyzer (VNA) measurements of the complete set of scattering parameters for the antenna used within the Long Wavelength Array (LWA) and the associated front end electronics (FEEs). Full scattering parameter measurements of the antenna yield not only the reflection coefficient for each polarization, S11 and S22, but also the coupling between polarizations, S12 and S21. These had been previously modeled using simulations, but direct measurements had not been obtained until now. The measurements are used to derive a frequency dependent impedance mismatch factor (IMF) which represents the fraction of power that is passed through the antenna-FEE interface and not reflected due to a mismatch between the impedance of the antenna and the impedance of the FEE. We also present results from a two antenna experiment where each antenna is hooked up to a separate port on the VNA. This allows for cross-antenna coupling to be measured for all four possible polarization combinations. Finally, we apply the newly measured IMF and FEE forward gain corrections to LWA data to investigate how well they remove instrumental effects.

Read this paper on arXiv…

C. DiLullo, W. Reeve, B. Hicks, et. al.
Tue, 28 Mar 23
40/81

Comments: 16 pages, 12 figures, Accepted for publication in Publications of the Astronomical Society of the Pacific

Science opportunities with solar sailing smallsats [EPA]

Posted on by

http://arxiv.org/abs/2303.14917


Recently, we witnessed how the synergy of small satellite technology and solar sailing propulsion enables new missions. Together, small satellites with lightweight instruments and solar sails offer affordable access to deep regions of the solar system, also making it possible to realize hard-to-reach trajectories that are not constrained to the ecliptic plane. Combining these two technologies can drastically reduce travel times within the solar system, while delivering robust science. With solar sailing propulsion capable of reaching the velocities of ~5-10 AU/yr, missions using a rideshare launch may reach the Jovian system in two years, Saturn in three. The same technologies could allow reaching solar polar orbits in less than two years. Fast, cost-effective, and maneuverable sailcraft that may travel outside the ecliptic plane open new opportunities for affordable solar system exploration, with great promise for heliophysics, planetary science, and astrophysics. Such missions could be modularized to reach different destinations with different sets of instruments. Benefiting from this progress, we present the “Sundiver” concept, offering novel possibilities for the science community. We discuss some of the key technologies, the current design of the Sundiver sailcraft vehicle and innovative instruments, along with unique science opportunities that these technologies enable, especially as this exploration paradigm evolves. We formulate policy recommendations to allow national space agencies, industry, and other stakeholders to establish a strong scientific, programmatic, and commercial focus, enrich and deepen the space enterprise and broaden its advocacy base by including the Sundiver paradigm as a part of broader space exploration efforts.

Read this paper on arXiv…

S. Turyshev, D. Garber, L. Friedman, et. al.
Tue, 28 Mar 23
43/81

Comments: 34 pages, 12 figures, 2 tables

Automated Speckle Interferometry of Known Binaries [IMA]

Posted on by

http://arxiv.org/abs/2303.15011


Astronomers have been measuring the separations and position angles between the two components of binary stars since William Herschel began his observations in 1781. In 1970, Anton Labeyrie pioneered a method, speckle interferometry, that overcomes the usual resolution limits induced by atmospheric turbulence by taking hundreds or thousands of short exposures and reducing them in Fourier space. Our 2022 automation of speckle interferometry allowed us to use a fully robotic 1.0-meter PlaneWave Instruments telescope, located at the El Sauce Observatory in the Atacama Desert of Chile, to obtain observations of many known binaries with established orbits. The long-term objective of these observations is to establish the precision, accuracy, and limitations of this telescope’s automated speckle interferometry measurements. This paper provides an early overview of the Known Binaries Project and provide example results on a small-separation (0.27″) binary, WDS 12274-2843 B 228.

Read this paper on arXiv…

N. Hardy, L. Bewersdorff, D. Rowe, et. al.
Tue, 28 Mar 23
45/81

Comments: N/A

The Need For Speed: Rapid Refitting Techniques for Bayesian Spectral Characterization of the Gravitational Wave Background Using PTAs [HEAP]

Posted on by

http://arxiv.org/abs/2303.15442


Current pulsar timing array (PTA) techniques for characterizing the spectrum of a nanohertz-frequency stochastic gravitational-wave background (SGWB) begin at the stage of timing data. This can be slow and memory intensive with computational scaling that will worsen PTA analysis times as more pulsars and observations are added. Given recent evidence for a common-spectrum process in PTA data sets and the need to understand present and future PTA capabilities to characterize the SGWB through large-scale simulations, we have developed efficient and rapid approaches that operate on intermediate SGWB analysis products. These methods refit SGWB spectral models to previously-computed Bayesian posterior estimations of the timing power spectra. We test our new methods on simulated PTA data sets and the NANOGrav $12.5$-year data set, where in the latter our refit posterior achieves a Hellinger distance from the current full production-level pipeline that is $\lesssim 0.1$. Our methods are $\sim10^2$–$10^4$ times faster than the production-level likelihood and scale sub-linearly as a PTA is expanded with new pulsars or observations. Our methods also demonstrate that SGWB spectral characterization in PTA data sets is driven by the longest-timed pulsars with the best-measured power spectral densities which is not necessarily the case for SGWB detection that is predicated on correlating many pulsars. Indeed, the common-process spectral properties found in the NANOGrav $12.5$-year data set are given by analyzing only the $\sim10$ longest-timed pulsars out of the full $45$ pulsar array, and we find that the “shallowing” of the common-process power-law model occurs when gravitational-wave frequencies higher than $\sim 50$~nanohertz are included. The implementation of our methods is openly available as a software suite to allow fast and flexible PTA SGWB spectral characterization and model selection.

Read this paper on arXiv…

W. Lamb, S. Taylor and R. Haasteren
Tue, 28 Mar 23
50/81

Comments: 19 pages, 12 figures. Submitting to Physical Review D

Pulsar and Magnetar Navigation with Fermi/GBM and GECAM [IMA]

Posted on by

http://arxiv.org/abs/2303.14490


The determination of the absolute and relative position of a spacecraft is critical for its operation, observations, data analysis, scientific studies, as well as deep space exploration in general. A spacecraft that can determine its own absolute position autonomously may perform more than that must rely on transmission solutions. In this work, we report an absolute navigation accuracy of $\sim$ 20 km using 16-day Crab pulsar data observed with $Fermi$ Gamma ray Burst Monitor (GBM). In addition, we propose a new method with the inverse process of the triangulation for joint navigation using repeated bursts like that from the magnetar SGR J1935+2154 observed by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) and GBM.

Read this paper on arXiv…

X. Luo, S. Xiao, S. Zheng, et. al.
Tue, 28 Mar 23
54/81

Comments: accepted for publication in ApJS

First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment [CL]

Posted on by

http://arxiv.org/abs/2303.14729


We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment which is based on a two-phase time projection chamber with a sensitive liquid xenon mass of $5.9$~t. During the approximately 1.1 tonne-year exposure used for this search, the intrinsic $^{85}$Kr and $^{222}$Rn concentrations in the liquid target were reduced to unprecedentedly low levels, giving an electronic recoil background rate of $(15.8\pm1.3)~\mathrm{events}/(\mathrm{t\cdot y \cdot keV})$ in the region of interest. A blind analysis of nuclear recoil events with energies between $3.3$~keV and $60.5$~keV finds no significant excess. This leads to a minimum upper limit on the spin-independent WIMP-nucleon cross section of $2.58\times 10^{-47}~\mathrm{cm}^2$ for a WIMP mass of $28~\mathrm{GeV}/c^2$ at $90\%$ confidence level. Limits for spin-dependent interactions are also provided. Both the limit and the sensitivity for the full range of WIMP masses analyzed here improve on previous results obtained with the XENON1T experiment for the same exposure.

Read this paper on arXiv…

X. Collaboration, E. Aprile, K. Abe, et. al.
Tue, 28 Mar 23
60/81

Comments: Limit points are included in the submission file

Looking for Stable Celestial Systems Using Bayesian Optimisation [IMA]

Posted on by

http://arxiv.org/abs/2303.14835


This paper presents a study of the use of numerical simulation and Bayesian optimisation techniques to investigate the dynamics of celestial systems. Initially, the study focuses on Lagrange points in restricted three-body systems where a 2D three-body system simulator is employed to locate the five Lagrange points. An appropriate loss function is developed to capture the gravitational stability of the system, and the stability properties of the different Lagrange points are explored. Additionally, the study investigates how varying the number of variables for the satellite impacts the search for the Lagrange points. Finally, the scope of the study is expanded to explore stable configurations in multi-star systems represented by regular convex n-gons. In this case, Bayesian optimisation is used to find suitable settings for the n-gon’s radius and the stars’ velocity vectors, such that the overall system is stable.

Read this paper on arXiv…

E. Fladmark, T. Reu and L. Justesen
Tue, 28 Mar 23
61/81

Comments: 10 pages

Convolutional Neural Networks for the classification of glitches in gravitational-wave data streams [CL]

Posted on by

http://arxiv.org/abs/2303.13917


We investigate the use of Convolutional Neural Networks (including the modern ConvNeXt network family) to classify transient noise signals (i.e.~glitches) and gravitational waves in data from the Advanced LIGO detectors. First, we use models with a supervised learning approach, both trained from scratch using the Gravity Spy dataset and employing transfer learning by fine-tuning pre-trained models in this dataset. Second, we also explore a self-supervised approach, pre-training models with automatically generated pseudo-labels. Our findings are very close to existing results for the same dataset, reaching values for the F1 score of 97.18% (94.15%) for the best supervised (self-supervised) model. We further test the models using actual gravitational-wave signals from LIGO-Virgo’s O3 run. Although trained using data from previous runs (O1 and O2), the models show good performance, in particular when using transfer learning. We find that transfer learning improves the scores without the need for any training on real signals apart from the less than 50 chirp examples from hardware injections present in the Gravity Spy dataset. This motivates the use of transfer learning not only for glitch classification but also for signal classification.

Read this paper on arXiv…

T. Fernandes, S. Vieira, A. Onofre, et. al.
Mon, 27 Mar 23
4/59

Comments: 15 pages, 14 figures

The Astri Mini-Array of Cherenkov Telescopes [HEAP]

Posted on by

http://arxiv.org/abs/2303.14079


We will describe the current status of the ASTRI Mini-Array, under construction at the Teide Astronomical Observatory in Tenerife, Spain. The final layout of the array will include nine small Cherenkov telescopes covering an area of about 650 x 270 square meters. The ASTRI telescopes adopt a dual-mirror Schwarzchild-Couder aplanatic optical design. In the focal plane, the ASTRI camera, based on silicon photo-multiplier detectors, will cover a large field-of-view ( > 10 deg in diameter). This system also provides good gamma-ray sensitivity at very high energies (VHE, above 10 TeV) combined with a good angular resolution. The scientific goals of the ASTRI Mini-Array include spectral and morphological characterization of the LHAASO sources and other Pevatron candidates, studies of PWNe and TeV halos, Blazar monitoring at VHE, fundamental physics and follow-up of transient events. The beginning of the scientific operations is planned for mid 2025. The first three years will be dedicated to the core science and the ASTRI Mini-Array will be run as an experiment. It will gradually move towards an observatory model in the following years, open to the community.

Read this paper on arXiv…

A. Giuliani
Mon, 27 Mar 23
6/59

Comments: Accepted Proceeding of the “7th Heidelberg International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2022)”, 4-8 July 2022, Barcelona, Spain

Designing wavelength sampling for Fabry-Pérot observations. Information-based spectral sampling [SSA]

Posted on by

http://arxiv.org/abs/2303.13875


Fabry-P\’erot interferometers (FPIs) have become very popular in solar observations because they offer a balance between cadence, spatial resolution, and spectral resolution through a careful design of the spectral sampling scheme according to the observational requirements of a given target. However, an efficient balance requires knowledge of the expected target conditions, the properties of the chosen spectral line, and the instrumental characteristics. Our aim is to find a method that allows finding the optimal spectral sampling of FPI observations in a given spectral region. In this study, we propose a technique based on a sequential selection approach where a neural network is used to predict the spectrum (or physical quantities, if the model is known) from the information at a few points. Only those points that contain relevant information and improve the model prediction are included in the sampling scheme. The method adapts the separation of the points according to the spectral resolution of the instrument, the typical broadening of the spectral shape, and the typical Doppler velocities. The experiments using the CaII 8542 A line show that the resulting wavelength scheme naturally places more points in the core than in the wings, consistent with the sensitivity of the spectral line at each wavelength interval. The method can also be used as an accurate interpolator, to improve the inference of the magnetic field when using the weak-field approximation. Overall, this method offers an objective approach for designing new instrumentation or observing proposals with customized configurations for specific targets. This is particularly relevant when studying highly dynamic events in the solar atmosphere with a cadence that preserves spectral coherence without sacrificing much information.

Read this paper on arXiv…

C. Baso, L. Voort, J. Rodríguez, et. al.
Mon, 27 Mar 23
10/59

Comments: 8 pages, 7 figures, accepted for publication in A&A

Implicit electric field Conjugation: Data-driven focal plane control [IMA]

Posted on by

http://arxiv.org/abs/2303.13719


Direct imaging of Earth-like planets is one of the main science cases for the next generation of extremely large telescopes. This is very challenging due to the star-planet contrast that must be overcome. Most current high-contrast imaging instruments are limited in sensitivity at small angular separations due to non-common path aberrations (NCPA). The NCPA leak through the coronagraph and create bright speckles that limit the on-sky contrast and therefore also the post-processed contrast. We aim to remove the NCPA by active focal plane wavefront control using a data-driven approach. We developed a new approach to dark hole creation and maintenance that does not require an instrument model. This new approach is called implicit Electric Field Conjugation (iEFC) and it can be empirically calibrated. This makes it robust for complex instruments where optical models might be difficult to realize. Numerical simulations have been used to explore the performance of iEFC for different coronagraphs. The method was validated on the internal source of the Magellan Adaptive Optics eXtreme (MagAO-X) instrument to demonstrate iEFC’s performance on a real instrument. Numerical experiments demonstrate that iEFC can achieve deep contrast below $10^{-9}$ with several coronagraphs. The method is easily extended to broadband measurements and the simulations show that a bandwidth up to 40% can be handled without problems. Experiments with MagAO-X showed a contrast gain of a factor 10 in a broadband light and a factor 20 to 200 in narrowband light. A contrast of $5\cdot10^{-8}$ was achieved with the Phase Apodized Pupil Lyot Coronagraph at 7.5 $\lambda/D$. The new iEFC method has been demonstrated to work in numerical and lab experiments. It is a method that can be empirically calibrated and it can achieve deep contrast. This makes it a valuable approach for complex ground-based high-contrast imaging systems.

Read this paper on arXiv…

S. Haffert, J. Males, K. Ahn, et. al.
Mon, 27 Mar 23
13/59

Comments: 13 pages, 12 figures accepted by A&A

The GALAH survey: New diffuse interstellar bands found in residuals of 872,000 stellar spectra [GA]

Posted on by

http://arxiv.org/abs/2303.14016


We use more than 872,000 mid-to-high resolution (R $\sim$ 20,000) spectra of stars from the GALAH survey to discern the spectra of diffuse interstellar bands (DIBs). We use four windows with the wavelength range from 4718 to 4903, 5649 to 5873, 6481 to 6739, and 7590 to 7890 \AA, giving a total coverage of 967 \AA. We produce $\sim$400,000 spectra of interstellar medium (ISM) absorption features and correct them for radial velocities of the DIB clouds. Ultimately, we combine the 33,115 best ISM spectra into six reddening bins with a range of $0.1 \,\mathrm{mag} < E\mathrm{(B-V)} < 0.7\, \mathrm{mag}$. A total of 183 absorption features in these spectra qualify as DIBs, their fitted model parameters are summarized in a detailed catalogue. From these, 64 are not reported in the literature, among these 17 are certain, 14 are probable and 33 are possible. We find that the broad DIBs can be fitted with a multitude of narrower DIBs. Finally, we create a synthetic DIB spectrum at unit reddening which should allow us to narrow down the possible carriers of DIBs and explore the composition of the ISM and ultimately better model dust and star formation as well as to correct Galactic and extragalactic observations. The majority of certain DIBs show a significant excess of equivalent width when compared to reddening. We explain this with observed lines of sight penetrating more uniform DIB clouds compared to clumpy dust clouds.

Read this paper on arXiv…

R. Vogrinčič, J. Kos, T. Zwitter, et. al.
Mon, 27 Mar 23
16/59

Comments: 28 pages, 15 figures, 11 tables, accepted for publication in MNRAS

APES: Approximate Posterior Ensemble Sampler [CEA]

Posted on by

http://arxiv.org/abs/2303.13667


This paper proposes a novel approach to generate samples from target distributions that are difficult to sample from using Markov Chain Monte Carlo (MCMC) methods. Traditional MCMC algorithms often face slow convergence due to the difficulty in finding proposals that suit the problem at hand. To address this issue, the paper introduces the Approximate Posterior Ensemble Sampler (APES) algorithm, which employs kernel density estimation and radial basis interpolation to create an adaptive proposal, leading to fast convergence of the chains. The APES algorithm’s scalability to higher dimensions makes it a practical solution for complex problems. The proposed method generates an approximate posterior probability that closely approximates the desired distribution and is easy to sample from, resulting in smaller autocorrelation times and a higher probability of acceptance by the chain. In this work, we compare the performance of the APES algorithm with the affine invariance ensemble sampler with the stretch move in various contexts, demonstrating the efficiency of the proposed method. For instance, on the Rosenbrock function, the APES presented an autocorrelation time 140 times smaller than the affine invariance ensemble sampler. The comparison showcases the effectiveness of the APES algorithm in generating samples from challenging distributions. This paper presents a practical solution to generating samples from complex distributions while addressing the challenge of finding suitable proposals. With new cosmological surveys set to deal with many new systematics, which will require many new nuisance parameters in the models, this method offers a practical solution for the upcoming era of cosmological analyses.

Read this paper on arXiv…

S. Vitenti and E. Barroso
Mon, 27 Mar 23
33/59

Comments: 15 pages, 6 figures, 7 tables

Alignment of the Alpha Magnetic Spectrometer (AMS) in space [CL]

Posted on by

http://arxiv.org/abs/2303.14072


The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector operating at an altitude of 410 km aboard the International Space Station. The AMS silicon tracker, together with the permanent magnet, measures the rigidity (momentum/charge) of cosmic rays in the range from 0.5 GV to several TV. In order to have accurate rigidity measurements, the positions of more than 2000 tracker modules have to be determined at the micron level by an alignment procedure. The tracker was first aligned using the 400 GeV/c proton test beam at CERN and then re-aligned using cosmic-ray events after being launched into space. A unique method to align the permanent magnetic spectrometer for a space experiment is presented. The developed underlying mathematical algorithm is discussed in detail.

Read this paper on arXiv…

Q. Yan and V. Choutko
Mon, 27 Mar 23
38/59

Comments: N/A

Electron transport measurements in liquid xenon with Xenoscope, a large-scale DARWIN demonstrator [CL]

Posted on by

http://arxiv.org/abs/2303.13963


There is a compelling physics case for a large, xenon-based underground detector devoted to dark matter and other rare-event searches. A two-phase time projection chamber as inner detector allows for a good energy resolution, a three-dimensional position determination of the interaction site and particle discrimination. To study challenges related to the construction and operation of a multi-tonne scale detector, we have designed and constructed a vertical, full-scale demonstrator for the DARWIN experiment at the University of Zurich. Here we present first results from a several-months run with 343 kg of xenon and electron drift lifetime and transport measurements with a 53 cm tall purity monitor immersed in the cryogenic liquid. After 88 days of continuous purification, the electron lifetime reached a value of 664(23) microseconds. We measured the drift velocity of electrons for electric fields in the range (25–75) V/cm, and found values consistent with previous measurements. We also calculated the longitudinal diffusion constant of the electron cloud in the same field range, and compared with previous data, as well as with predictions from an empirical model.

Read this paper on arXiv…

L. Baudis, Y. Biondi, A. Bismark, et. al.
Mon, 27 Mar 23
48/59

Comments: N/A

Photometric Catalogue for Space and Ground Night-Time Remote-Sensing Calibration: RGB Synthetic Photometry from Gaia DR3 Spectrophotometry [IMA]

Posted on by

http://arxiv.org/abs/2303.14147


Recent works have made strong efforts to produce standardised photometry in RGB bands. For this purpose, we carefully defined the transmissivity curves of RGB bands and defined a set of standard sources using the photometric information present in Gaia EDR3. This work aims not only to significantly increase the number and accuracy of RGB standards but also to provide, for the first time, reliable uncertainty estimates using the BP and RP spectrophotometry published in Gaia DR3 instead of their integrated photometry to predict RGB photometry. Furthermore, this method allows including calibrated sources regardless of how they are affected by extinction, which was a major shortcoming of previous work. The RGB photometry is synthesised from the Gaia BP and RP low-resolution spectra by directly using their set of coefficients multiplied with some basis functions provided in the Gaia catalogue for all sources published in Gaia DR3. The output synthetic magnitudes are compared with the previous catalogue of RGB standards available.

Read this paper on arXiv…

J. Carrasco, N. Cardiel, E. Masana, et. al.
Mon, 27 Mar 23
55/59

Comments: 23 pages, 15 figures

Extragalactic magnetism with SOFIA (SALSA Legacy Program) — V: First results on the magnetic field orientation of galaxies [GA]

Posted on by

http://arxiv.org/abs/2303.13586


We present the analysis of the magnetic field ($B$-field) structure of galaxies measured with far-infrared (FIR) and radio (3 and 6 cm) polarimetric observations. We use the first data release of the Survey on extragALactic magnetiSm with SOFIA (SALSA) of 14 nearby ($<20$ Mpc) galaxies with resolved (5 arcsec-18 arcsec; $90$ pc–$1$ kpc) imaging polarimetric observations using HAWC+/SOFIA from $53$ to $214$ \um. We compute the magnetic pitch angle ($\Psi_{B}$) profiles as a function of the galactrocentric radius. We introduce a new magnetic alignment parameter ($\zeta$) to estimate the disordered-to-ordered $B$-field ratio in spiral $B$-fields. We find FIR and radio wavelengths to not generally trace the same $B$-field morphology in galaxies. The $\Psi_{B}$ profiles tend to be more ordered with galactocentric radius in radio ($\zeta_{\rm{6cm}} = 0.93\pm0.03$) than in FIR ($\zeta_{\rm{154\mu m}} = 0.84\pm0.14$). For spiral galaxies, FIR $B$-fields are $2-75$\% more turbulent than the radio $B$-fields. For starburst galaxies, we find that FIR polarization is a better tracer of the $B$-fields along the galactic outflows than radio polarization. Our results suggest that the $B$-fields associated with dense, dusty, turbulent star-forming regions, those traced at FIR, are less ordered than warmer, less-dense regions, those traced at radio, of the interstellar medium. The FIR $B$-fields seem to be more sensitive to the activity of the star-forming regions and the morphology of the molecular clouds within a vertical height of few hundred pc in the disk of spiral galaxies than the radio $B$-fields.

Read this paper on arXiv…

A. Borlaff, E. Lopez-Rodriguez, R. Beck, et. al.
Mon, 27 Mar 23
59/59

Comments: 26 pages, 13 figures

Seeing-limited Coupling of Starlight into Single-mode Fiber with a Small Telescope [IMA]

Posted on by

http://arxiv.org/abs/2303.12972


An optical fiber link to a telescope provides many advantages for spectrometers designed to detect and characterize extrasolar planets through precise radial velocity (PRV) measurements. In the seeing-limited regime, a multi-mode fiber is typically used so that a significant amount of starlight may be captured. In the near-diffraction-limited case, either with an adaptive optics system or with a small telescope at an excellent site, efficiently coupling starlight into a much smaller, single-mode fiber may be possible. In general, a spectrometer designed for single-mode fiber input will be substantially less costly than one designed for multi-mode fiber input. We describe the results of tests coupling starlight from a 70 cm telescope at Mt. Hopkins, Arizona into the single-mode fiber of the MINERVA-Red spectrometer at a wavelength of ~850 nm using a low-speed tip/tilt image stabilization system comprising all commercial, off-the-shelf components. We find that approximately 0.5% of the available starlight is coupled into the single-mode fiber under seeing conditions typical for observatories hosting small telescopes, which is close to the theoretical expectation. We discuss scientific opportunities for small telescopes paired with inexpensive, high-resolution spectrometers, as well as upgrade paths that should significantly increase the coupling efficiency for the MINERVA-Red system.

Read this paper on arXiv…

D. Sliski, C. Blake, J. Eastman, et. al.
Fri, 24 Mar 23
1/56

Comments: 8 pages, 4 figures. Accepted for publication in Astronomische Nachrichten

On orbit performance of the solar flare trigger for the Hinode EUV Imaging Spectrometer [SSA]

Posted on by

http://arxiv.org/abs/2303.13155


We assess the on-orbit performance of the flare event trigger for the Hinode EUV Imaging Spectrometer. Our goal is to understand the time-delay between the occurrence of a flare, as defined by a prompt rise in soft X-ray emission, and the initiation of the response observing study. Wide (266$”$) slit patrol images in the He II 256.32A spectral line are used for flare hunting, and a reponse is triggered when a pre-defined intensity threshold is reached. We use a sample of 13 $>$ M-class flares that succesfully triggered a response, and compare the timings with soft X-ray data from GOES, and hard X-ray data from RHESSI and Fermi. Excluding complex events that are difficult to interpret, the mean on orbit response time for our sample is 2 min 10 s, with an uncertainty of 84 s. These results may be useful for planning autonomous operations for future missions, and give some guidance as to how improvements could be made to capture the important impulsive phase of flares.

Read this paper on arXiv…

D. Brooks, J. Reep, I. Ugarte-Urra, et. al.
Fri, 24 Mar 23
10/56

Comments: To be published as a Brief Report in Frontiers in Astronomy and Space Sciences

A Quick Look at the 3GHz Radio Sky. II. Hunting for DRAGNs in the VLA Sky Survey [GA]

Posted on by

http://arxiv.org/abs/2303.12830


Active Galactic Nuclei (AGN) can often be identified in radio images as two lobes, sometimes connected to a core by a radio jet. This multi-component morphology unfortunately creates difficulties for source-finders, leading to components that are a) separate parts of a wider whole, and b) offset from the multiwavelength cross identification of the host galaxy. In this work we define an algorithm, DRAGNhunter, for identifying Double Radio Sources associated with Active Galactic Nuclei (DRAGNs) from component catalog data in the first epoch images of the high resolution ($\approx 3”$ beam size) Very Large Array Sky Survey (VLASS). We use DRAGNhunter to construct a catalog of $>17,000$ DRAGNs in VLASS for which contamination from spurious sources estimated at $\approx 11\,\%$. A `high-fidelity’ sample consisting of $90\,\%$ of our catalog is identified for which contamination is $<3\,\%$. Host galaxies are found for $\approx 13,000$ DRAGNs as well as for an additional $234,000$ single-component radio sources. Using these data we explore the properties of our DRAGNs, finding them to be typically consistent with Fanaroff-Riley class II sources and allowing us to report the discovery of $31$ new giant radio galaxies identified using VLASS.

Read this paper on arXiv…

Y. Gordon, L. Rudnick, H. Andernach, et. al.
Fri, 24 Mar 23
12/56

Comments: 34 pages, 25 figures, 7 tables, submitted to ApJS. Associated catalog to be release by CIRADA at this https URL

Stochastic Recurrent Neural Networks for Modelling Astronomical Time Series: Advantages and Limitations [IMA]

Posted on by

http://arxiv.org/abs/2303.13197


This paper reviews the Stochastic Recurrent Neural Network (SRNN) as applied to the light curves of Active Galactic Nuclei by Sheng et al. (2022). Astronomical data have inherent limitations arising from telescope capabilities, cadence strategies, inevitable observing weather conditions, and current understanding of celestial objects. When applying machine learning methods, it is vital to understand the effects of data limitations on our analysis and ability to make inferences. We take Sheng et al. (2022) as a case study, and illustrate the problems and limitations encountered in implementing the SRNN for simulating AGN variability as seen by the Rubin Observatory.

Read this paper on arXiv…

X. Sheng, M. Nicholl and N. Ross
Fri, 24 Mar 23
19/56

Comments: To appear in proceedings of EAS 2022 S11 session on machine learning in astronomy

A Catalogue of Exoplanet Atmospheric Retrieval Codes [EPA]

Posted on by

http://arxiv.org/abs/2303.12925


Exoplanet atmospheric retrieval is a computational technique widely used to infer properties of planetary atmospheres from remote spectroscopic observations. Retrieval codes typically employ Bayesian sampling algorithms or machine learning approaches to explore the range of atmospheric properties (e.g., chemical composition, temperature structure, aerosols) compatible with an observed spectrum. However, despite the wide adoption of exoplanet retrieval techniques, there is currently no systematic summary of exoplanet retrieval codes in the literature. Here, we provide a catalogue of the atmospheric retrieval codes published to date, alongside links to their respective code repositories where available. Our catalogue will be continuously updated via a Zenodo archive.

Read this paper on arXiv…

R. MacDonald and N. Batalha
Fri, 24 Mar 23
25/56

Comments: 5 pages, 1 giant Table. Published in RNAAS. Live catalogue will be updated at this https URL

Temporal Intensity Interferometry at a 0.5 m Telescope [IMA]

Posted on by

http://arxiv.org/abs/2303.13265


Intensity interferometry correlates light intensities rather than amplitudes of individual telescopes to recover the source geometry. While intensity correlations can alleviate the technical challenges of amplitude interferometry, and thus enable the realization of larger baselines and therefore higher resolution in astronomical imaging, this comes at the cost of greatly reduced sensitivity. We report the observation of photon bunching in the light of $\alpha$ Lyrae (Vega), measured with a telescope of merely 0.5m in diameter (Planewave CDK 20). The entire measurement setup, including collimation, optical filtering, and detection, was attached directly to the telescope without the use of optical fibers, facilitated by the large area of our single photon detectors. After a total exposure time of 32.4h over the course of six nights, a correlation signal with a contrast of $(9.5 \pm 2.7) \cdot 10^{-3}$ and a coherence time $0.34 \pm 0.12$ps was recovered, fitting well to preceding laboratory tests as well as expectations calculated from the optical and electronic characteristics of our measurement setup.

Read this paper on arXiv…

S. Karl, S. Richter and J. Zanthier
Fri, 24 Mar 23
33/56

Comments: N/A