The Impact of Progenitor Mass Loss on the Dynamical and Spectral Evolution of Supernova Remnants [HEAP]

There is now substantial evidence that the progenitors of some core-collapse supernovae undergo enhanced or extreme mass loss prior to explosion. The imprint of this mass loss is observed in the spectra and dynamics of the expanding blastwave on timescales of days to years after core-collapse, and the effects on the spectral and dynamical evolution may linger long after the supernova has evolved into the remnant stage. In this paper, we present for the first time, largely self-consistent end-to-end simulations for the evolution of a massive star from the pre-main sequence, up to and through core collapse, and into the remnant phase. We present three models and compare and contrast how the progenitor mass loss history impacts the dynamics and spectral evolution of the supernovae and supernova remnants. We study a model which only includes steady mass loss, a model with enhanced mass loss over a period of $\sim$ 5000 years prior to core-collapse, and a model with extreme mass loss over a period of $\sim$ 500 years prior to core collapse. The models are not meant to address any particular supernova or supernova remnant, but rather to highlight the important role that the progenitor evolution plays in the observable qualities of supernovae and supernova remnants. Through comparisons of these three different progenitor evolution scenarios, we find that the mass loss in late stages (during and after core carbon burning) can have a profound impact on the dynamics and spectral evolution of the supernova remnant centuries after core-collapse.

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D. Patnaude, S. Lee, P. Slane, et. al.
Thu, 17 Aug 17

Comments: 18 pages, 11 figures; submitted to the Astrophysical Journal

The mass function of GX 339-4 from spectroscopic observations of its donor star [HEAP]

We obtained 16 VLT/X-shooter observations of GX 339-4 in quiescence in the period May – September 2016 and detected absorption lines from the donor star in its NIR spectrum. This allows us to measure the radial velocity curve and projected rotational velocity of the donor for the first time. We confirm the 1.76 day orbital period and we find that $K_2$ = $219 \pm 3$ km s$^{-1}$, $\gamma = 26 \pm 2$ km s$^{-1}$ and $v \sin i = 64 \pm 8$ km s$^{-1}$. From these values we compute a mass function $f(M) =1.91 \pm 0.08~M_{\odot}$, a factor $\sim 3$ lower than previously reported, and a mass ratio $q = 0.18 \pm 0.05$. We confirm the donor is a K-type star and estimate that it contributes $\sim 45-50\%$ of the light in the $J$- and H-band. We constrain the binary inclination to $37^\circ < i < 78^\circ$ and the black hole mass to $2.3~M_{\odot} < M_\mathrm{BH} < 9.5~M_{\odot}$. GX 339-4 may therefore be the first black hole to fall in the ‘mass-gap’ of $2-5~M_{\odot}$.

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M. Heida, P. Jonker, M. Torres, et. al.
Thu, 17 Aug 17

Comments: 11 pages, 7 figures, accepted for publication in ApJ

Large Magellanic Cloud Near-Infrared Synoptic Survey. V. Period-Luminosity Relations of Miras [SSA]

We study the near-infrared properties of 690 Mira candidates in the central region of the Large Magellanic Cloud, based on time-series observations at JHKs. We use densely-sampled I-band observations from the OGLE project to generate template light curves in the near infrared and derive robust mean magnitudes at those wavelengths. We obtain near-infrared Period-Luminosity relations for Oxygen-rich Miras with a scatter as low as 0.12 mag at Ks. We study the Period-Luminosity-Color relations and the color excesses of Carbon-rich Miras, which show evidence for a substantially different reddening law.

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W. Yuan, L. Macri, S. He, et. al.
Thu, 17 Aug 17

Comments: Accepted for publication in The Astronomical Journal

Mary, a pipeline to aid discovery of optical transients [IMA]

The ability to quickly detect transient sources in optical images and trigger multi-wavelength follow up is key for the discovery of fast transients. These include events rare and difficult to detect such as kilonovae, supernova shock breakout, and “orphan” Gamma-ray Burst afterglows. We present the Mary pipeline, a (mostly) automated tool to discover transients during high-cadenced observations with the Dark Energy Camera (DECam) at CTIO. The observations are part of the “Deeper Wider Faster” program, a multi-facility, multi-wavelength program designed to discover fast transients, including counterparts to Fast Radio Bursts and gravitational waves. Our tests of the Mary pipeline on DECam images return a false positive rate of ~2.2% and a missed fraction of ~3.4% obtained in less than 2 minutes, which proves the pipeline to be suitable for rapid and high-quality transient searches. The pipeline can be adapted to search for transients in data obtained with imagers other than DECam.

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I. Andreoni, C. Jacobs, S. Hegarty, et. al.
Thu, 17 Aug 17

Comments: Accepted for publication in PASA; 15 pages, 7 figures, 3 tables

Equation of state SAHA-S meets stellar evolution code CESAM2k [SSA]

We present an example of an interpolation code of the SAHA-S equation of state that has been adapted for use in the stellar evolution code CESAM2k. The aim is to provide the necessary data and numerical procedures for its implementation in a stellar code. A technical problem is the discrepancy between the sets of thermodynamic quantities provided by the SAHA-S equation of state and those necessary in the CESAM2k computations. Moreover, the independent variables in a practical equation of state (like SAHA-S) are temperature and density, whereas for modelling calculations the variables temperature and pressure are preferable. Specifically for the CESAM2k code, some additional quantities and their derivatives must be provided. To provide the bridge between the equation of state and stellar modelling, we prepare auxiliary tables of the quantities that are demanded in CESAM2k. Then we use cubic spline interpolation to provide both smoothness and a good approximation of the necessary derivatives. Using the B-form of spline representation provides us with an efficient algorithm for three-dimensional interpolation. The table of B-spline coefficients provided can be directly used during stellar model calculations together with the module of cubic spline interpolation. This implementation of the SAHA-S equation of state in the CESAM2k stellar structure and evolution code has been tested on a solar model evolved to the present. A comparison with other equations of state is briefly discussed. The choice of a regular net of mesh points for specific primary quantities in the SAHA-S equation of state, together with accurate and consistently smooth tabulated values, provides an effective algorithm of interpolation in modelling calculations. The proposed module of interpolation procedures can be easily adopted in other evolution codes.

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V. Baturin, W. Dappen, P. Morel, et. al.
Thu, 17 Aug 17

Comments: 8 pages, 5 figures

SDSS-IV MaStar: a Large, Comprehensive, and High Quality Empirical Stellar Library [GA]

We introduce the ongoing MaStar project, which is going to construct a large, well-calibrated, high quality empirical stellar library with more than 8000 stars covering the wavelength range from 3622 to 10,354A at a resolution of R~2000, and with better than 3% relative flux calibration. The spectra are taken using hexagonal fiber bundles feeding the BOSS spectrographs on the 2.5m Sloan Foundation Telescope, by piggybacking on the SDSS-IV/APOGEE-2 observations. Compared to previous efforts of empirical libraries, the MaStar Library will have a more comprehensive stellar parameter coverage, especially in cool dwarfs, low metallicity stars, and stars with different [alpha/Fe]. This is achieved by a target selection method based on large spectroscopic catalogs from APOGEE, LAMOST, and SEGUE, combined with photometric selection. This empirical library will provide a new basis for calibrating theoretical spectral libraries and for stellar population synthesis. In addition, with identical spectral coverage and resolution to the ongoing integral field spectroscopy survey of nearby galaxies — SDSS-IV/MaNGA (Mapping Nearby Galaxies at APO). This library is ideal for spectral modeling and stellar population analysis of MaNGA data.

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R. Yan and MaStar. Team
Thu, 17 Aug 17

Comments: Conference proceeding for the International Workshop on Spectral Stellar Libraries held in Campos de Jordao, SP, Brazil in Feburary 2017

Modelling uncertainty of the radiation energy emitted by extensive air showers [HEAP]

Recently, the energy determination of extensive air showers using radio emission has been shown to be both precise and accurate. In particular, radio detection offers the opportunity for an independent measurement of the absolute energy of cosmic rays, since the radiation energy (the energy radiated in the form of radio signals) can be predicted using first-principle calculations involving no free parameters, and the measurement of radio waves is not subject to any significant absorption or scattering in the atmosphere. Here, we verify the implementation of radiation-energy calculations from microscopic simulation codes by comparing Monte Carlo simulations made with the two codes CoREAS and ZHAireS. To isolate potential differences in the radio-emission calculation from differences in the air-shower simulation, the simulations are performed with equivalent settings, especially the same model for the hadronic interactions and the description of the atmosphere. Comparing a large set of simulations with different primary energies and shower directions we observe differences amounting to a total of only 3.3 %. This corresponds to an uncertainty of only 1.6 % in the determination of the absolute energy scale and thus opens the potential of using the radiation energy as an accurate calibration method for cosmic ray experiments.

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M. Gottowik, C. Glaser, T. Huege, et. al.
Thu, 17 Aug 17

Comments: 8 pages, 2 figures, ICRC2017 contribution