The jet-ISM interactions in IC 5063 [HEAP]

The interstellar medium of the radio galaxy IC 5063 is highly perturbed by an AGN jet expanding in the gaseous disc of the galaxy. We model this interaction with relativistic hydrodynamic simulations and multiphase initial conditions for the interstellar medium and compare the results with recent observations. As the jets flood through the inter-cloud channels of the disc, they ablate, accelerate, and disperse clouds to velocities exceeding $400 \mbox{km s}^{-1}$. Clouds are also destroyed or displaced in bulk from the central regions of the galaxy. Our models with jet powers of $10^{44} \mbox{erg s}^{-1}$ and $10^{45} \mbox{erg s}^{-1}$ are capable of reproducing many of the features seen in the position-velocity diagram published in Morganti et al. (2015) and confirm the notion that the jet is responsible for the strongly perturbed gas dynamics seen in the ionized, neutral, and molecular gas phases. In our simulations, we also see strong venting of the jet plasma perpendicular to the disc, which entrains clumps and diffuse filaments into the halo of the galaxy. Our simulations are the first 3D hydrodynamic simulations of the jet and ISM of IC 5063.

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D. Mukherjee, A. Wagner, G. Bicknell, et. al.
Tue, 23 Jan 18

Comments: Accepted for publication in MNRAS

Search for Ultra-High Energy WIMPs by detecting neutrino signatures from the earth core [HEAP]

I study the possibility of probing Ultra-High Energy (UHE from now on) dark matter particles (>10$^8$ GeV) due to the decay of superheavy dark matter via detection of UHE neutrino signatures from the earth core. The UHE WIMP event rates are estimated at the energies of 100 PeV, and 1 EeV, 10 EeV, 100 EeV and 1 ZeV in JEM-EUSO and at the energy of 1 ZeV in IceCube, respectively. The diffuse neutrino contaminations are also roughly estimated in JEM-EUSO and IceCube. I found that the extreme energy WIMPs can be detected by JEM-EUSO above 1 EeV and by IceCube above 1 ZeV in the $\chi$ mass range of 10GeV-200GeV.

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Y. Xu
Tue, 23 Jan 18

Comments: 13 pages, 8 figures

Optical/infrared polarised emission in X-ray binaries [HEAP]

Recently, evidence for synchrotron emission in both black hole and neutron star X-ray binaries has been mounting, from optical/infrared spectral, polarimetric, and fast timing signatures. The synchrotron emission of jets can be highly linearly polarised, depending on the configuration of the magnetic field. Optical and infrared (OIR) polarimetric observations of X-ray binaries are presented in this brief review. The OIR polarimetric signature of relativistic jets is detected at levels of ~ 1-10 %, similar to AGN cores. This reveals that the magnetic geometry in the compact jets may be similar for supermassive and stellar-mass BHs. The magnetic fields near the jet base in most of these systems appear to be turbulent, variable and on average, aligned with the jet axis, although there are some exceptions. These measurements probe the physical conditions in the accretion (out)flow and demonstrate a new way of connecting inflow and outflow, using both rapid timing and polarisation. Variations in polarisation could be due to rapid changes of the ordering of the magnetic field in the emitting region, or in one case, flares from individual ejections or collisions between ejecta. It is predicted that in some cases, variable levels of X-ray polarisation from synchrotron emission originating in jets will be detected from accreting Galactic black holes with upcoming spaceborne X-ray polarimeters.

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D. Russell
Tue, 23 Jan 18

Comments: 6 pages short review; Accepted by MDPI Galaxies; Conference Proceedings for ‘Polarised Emission from Astrophysical Jets’, June 12-16, 2017, Ierapetra, Greece this http URL

Broad-line type Ic Supernova SN 2014ad [HEAP]

We present optical and ultraviolet photometry, and low resolution optical spectroscopy of the broad-line type Ic supernova SN 2014ad in the galaxy PGC 37625 (Mrk 1309), covering the evolution of the supernova during $-$5 to +87 d with respect to the date of maximum in $B$-band. A late phase spectrum obtained at +340 d is also presented. With an absolute $V$ band magnitude at peak of $M_{V}$ = $-$18.86 $\pm$ 0.23 mag, SN 2014ad is fainter than Gamma Ray Burst (GRB) associated supernovae, and brighter than most of the normal and broad-line type Ic supernovae without an associated GRB. The spectral evolution indicates the expansion velocity of the ejecta, as measured using the Si\,{\sc ii} line, to be as high as $\sim$ 33500 km\,s$^{-1}$ around maximum, while during the post-maximum phase it settles down at $\sim$ 15000 km\,s$^{-1}$. The expansion velocity of SN 2014ad is higher than all other well observed broad-line type Ic supernovae except the GRB associated SN 2010bh. The explosion parameters, determined by applying the Arnett’s analytical light curve model to the observed bolometric light curve, indicate that it was an energetic explosion with a kinetic energy of $\sim$ (1 $\pm$ 0.3)$\times$10$^{52}$ ergs, a total ejected mass of $\sim$ (3.3 $\pm$ 0.8) M$\odot$, and $\sim$ 0.24 M$\odot$ of $^{56}$Ni was synthesized in the explosion. The metallicity of the host galaxy near the supernova region is estimated to be $\sim$ 0.5 Z$_\odot$.

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D. Sahu, G. Anupama, N. Chakradhari, et. al.
Tue, 23 Jan 18

Comments: 15 pages, 17 figures and 4 tables. Accepted for publication in MNRAS main journal

Fast radio bursts' recipes for the distributions of dispersion measures, flux densities, and fluences [HEAP]

We investigate how the statistical properties of dispersion measure (DM) and apparent flux density/fluence of (non-repeating) fast radio bursts (FRBs) are determined by unknown cosmic rate density history [$\rhoFRB (z)$] and luminosity function (LF) of the transient events. We predict the distributions of DMs, flux densities, and fluences of FRBs taking account of the variation of the receiver efficiency within its beam, using analytical models of $\rhoFRB (z)$ and LF. Comparing the predictions with the observations, we show that the cumulative distribution of apparent fluences suggests that FRBs originate at cosmological distances and $\rhoFRB$ increases with redshift resembling cosmic star formation history (CSFH). We also show that a LF model with a bright-end cutoff at log${10}L\nu$ [erg s$^{-1}$Hz$^{-1}$] $\sim$ 34 are favored to reproduce the observed DM distribution if $\rhoFRB (z)\propto$ CSFH, although the statistical significance of the constraints obtained with the current size of the observed sample is not high. Finally, we find that the correlation between DM and flux density of FRBs is potentially a powerful tool to distinguish whether FRBs are at cosmological distances or in the local universe more robustly with future observations.

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Y. Niino
Tue, 23 Jan 18

Comments: 12 pages, 13 figures, submitted to ApJ

A Study of Low-Mass X-Ray Binaries in the Low-Luminosity Regime [HEAP]

A recent study of a small sample of X-ray binaries (XRBs) suggests a significant softening of spectra of neutron star (NS) binaries as compared to black hole (BH) binaries in the luminosity range 10$^{34}$ – 10$^{37}$ erg/s. This softening is quantified as an anticorrelation between the spectral index and the 0.5 – 10 keV X-ray luminosity. We extend the study to significantly lower luminosities (i.e., $\sim$ a few $\times$ $10^{30}$ erg/s) for a larger sample of XRBs. We find evidence for a significant anticorrelation between the spectral index and the luminosity for a group of NS binaries in the luminosity range 10$^{32}$ to 10$^{33}$ erg/s. Our analysis suggests a steep slope for the correlation i.e., -2.12 $\pm$ 0.63. In contrast, BH binaries do not exhibit the same behavior. We examine the possible dichotomy between NS and BH binaries in terms of a Comptonization model that assumes a feedback mechanism between an optically thin hot corona and an optically thick cool source of soft photons. We gauge the NS-BH dichotomy by comparing the extracted corona temperatures, Compton-y parameters and the Comptonization amplification factors: The mean temperature of the NS group is found to be significantly lower than the equivalent temperature for the BH group. The extracted Compton-y parameters and the amplification factors follow the theoretically predicted relation with the spectral index.

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E. Sonbas, K. Dhuga and E. Gogus
Tue, 23 Jan 18

Comments: Accepted for publication in ApJ

Gravitational wave bursts from long gamma-ray bursts [HEAP]

One of the most luminous explosions detected, gamma-ray bursts, especially the so-called long-duration bursts, most probably consist of an intrinsic core-collapse to a black hole inside a super massive star. We point out that this collapse alone will give a generic gravitational wave burst. It has been shown that the strength of this burst depends on the dimensionless spin parameter of the collapsing object. Under descent assumptions the gamma-ray burst’s central engine powers the explosion electromagnetically due to the rotation of the newly formed black hole. We argue that the peak luminosity and the isotropic energy of the gamma-ray burst can be associated with the spin of the black hole, due to this mechanism. Since, both gravitational and electromagnetic emission depend on the spin, they can be correlated and thus give a straight estimate for the gravitational wave burst, when we have in hand a gamma-ray burst with known distance. We discuss detectability limits for present and future detectors.

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A. Nathanail and M. Laurentis
Tue, 23 Jan 18

Comments: 6 pages, submitted