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

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

Contribution to diffuse gamma-ray emission coming from self-confined CRs around their Galactic sources [HEAP]

Recent observations of the diffuse Galactic gamma-ray emission by the Fermi-LAT satellite have shown significant deviations from models which assume the same diffusion properties for cosmic rays (CR) throughout the Galaxy. We explore the possibility that a fraction of this diffuse Galactic emission could be due to hadronic interactions of CRs self-confined in the region around their sources. In fact, freshly accelerated CRs that diffuse away from the acceleration region can trigger the streaming instability able to amplify magnetic disturbance and to reduce the particle diffusion. When this happen, CRs are trapped in the near source region for a time longer than expected and an extended gamma-ray halo is produces around each source. Here we calculate the contribution to the diffuse gamma-ray background due to the overlap along lines of sight of several of these extended halos. We find that if the density of neutrals is low, the halos can account for a substantial fraction of the diffuse emission observed by Fermi-LAT, depending on the orientation of the line of sight with respect to the direction of the galactic center.

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G. Morlino, M. DAngelo, P. Blasi, et. al.
Thu, 17 Aug 17

Comments: 8 pages, 2 figs. Proceeding the 35th International Cosmic Ray Conference (ICRC2017), Bexco, Busan, Korea

Electron and proton heating in trans-relativistic magnetic reconnection [HEAP]

The coronae of collisionless accretion flows, such as Sgr A* at our Galactic center, provide a unique setting for the investigation of magnetic reconnection. Here, protons are non-relativistic while electrons can be ultra-relativistic. By means of 2D PIC simulations, we study electron and proton heating in the outflows of trans-relativistic ($\sigma_w$~0.1, where the magnetization $\sigma_w$ is the ratio of magnetic energy density to enthalpy density) anti-parallel reconnection. We explore the dependence of the heating efficiency on mass ratio (up to the realistic value), magnetization $\sigma_w$, proton plasma $\beta_i$ (the ratio of proton thermal pressure to magnetic pressure), and electron-to-proton temperature ratio $T_e/T_i$. For both electrons and protons, heating at high $\beta_i$ is dominated by adiabatic compression (adiabatic heating), while at low $\beta_i$ it is accompanied by a genuine increase in entropy (irreversible heating). For our fiducial $\sigma_w=0.1$, we find that at $\beta_i<1$ the irreversible heating efficiency is nearly independent of $T_e/T_i$ (which we vary from 0.1 up to 1). If $T_e/T_i=1$, the fraction of inflowing magnetic energy converted to electron irreversible heating decreases from ~0.016 down to ~0.002 as $\beta_i$ ranges from ~0.01 up to ~0.5, but then it increases up to ~0.03 as $\beta_i$ approaches ~2. Protons are heated more efficiently than electrons at low and moderate $\beta_i$ (by a factor of ~7), whereas the electron and proton heating efficiencies become comparable at $beta_i$~2 if $T_e/T_i=1$, when both species start already relativistically hot. We find comparable heating efficiencies between the two species also in the limit of relativistic reconnection, when the magnetization exceeds unity. Our results have important implications for the two-temperature nature of collisionless accretion flows, and may provide the sub-grid physics needed in general relativistic MHD simulations.

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M. Rowan, L. Sironi and R. Narayan
Thu, 17 Aug 17

Comments: 26 pages, 25 figures, 6 appendices; submitted to ApJ

The HelMod Monte Carlo Model for the Propagation of Cosmic Rays in Heliosphere [HEAP]

The heliospheric modulation model HelMod solve the transport-equation for the Galactic Cosmic Rays propagation through the heliosphere down to Earth. It is based on a 2-D Monte Carlo approach, that includes a general description of the symmetric and antisymmetric parts of the diffusion tensor, thus, properly treating the particle drift effects as well as convection within the solar wind and adiabatic energy loss. The model was tuned in order to fit 1) the data observed outside the ecliptic plane at several distances from the Earth and 2) the spectra observed near the Earth for both, high and low solar activity periods. Great importance was given to description of polar regions of the heliosphere. We present the flux for protons, antiprotons and helium nuclei computed along the solar cycle 23-24 in comparison with experimental observations and prediction for the full solar cycle 24.

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M. Boschini, S. Torre, M. Gervasi, et. al.
Thu, 17 Aug 17

Comments: 4 pages, 2 figures, proceedings of IAU Symposium 335 – Space Weather of the Heliosphere: Processes and Forecasts, July 17-21, 2017, University of Exeter, UK

Searching for TeV DM evidence from Dwarf Irregular Galaxies with the HAWC Observatory [HEAP]

The dynamics of dwarf irregular (dIrr) galaxies are observed to be dominated by dark matter (DM). Recently, the DM density distribution has been studied for 31 dIrrs. Their extended DM halo (Burket type profile) makes these objects good candidates for DM searches. Located in Puebla (Mexico), the High Altitude Water Cherenkov (HAWC) Observatory is an optimal in- strument to perform such DM searches, because of its large sky coverage (8.4 sr per day). We analyzed a set of two years of HAWC data and we found no significant DM signal from dIrr galaxies. We present the upper limits for DM annihilation cross-section with dIrr galaxies.

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S. Cadena, R. Alfaro, A. Sandoval, et. al.
Thu, 17 Aug 17

Comments: Presented at the 35th International Cosmic Ray Conference (ICRC2017), Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contributions