Search

The Fermi Large Area Telescope (Fermi-LAT) Collaboration reported the Second Gamma-ray Burst Catalog (2FLGC), which comprises a subset of 29 bursts with photon energies above 10 GeV. Although the standard synchrotron forward-shock model has successfully explained the Gamma-ray burst (GRB) afterglow observations, energetic photons higher than 10 GeV from these transient events can hardly be described in this scenario. We present the closure relations (CRs) of synchrotron self-Compton (SSC) afterglow model in the adiabatic and radiative scenario and when the central engine injects continuous energy into the blastwave to study the evolution of the spectral and temporal indexes of those bursts reported in 2FLGC. We consider the SSC afterglow model evolving in stellar-wind and interstellar medium, and the CRs as a function of the radiative parameter, the energy injection index, and the electron spectral index for $1

The Neil Gehrels Swift observatory observe Gamma-Ray bursts (GRBs) plateaus in X-rays. We test the reliability of the closure relations through the fireball model when dealing with the GRB plateau emission. We analyze 455 X-ray lightcurves (LCs) collected by \emph{Swift} from 2005 (January) until 2019 (August) for which the redshift is both known and unknown using the phenomenological Willingale 2007 model. Using these fits, we analyze the emission mechanisms and astrophysical environments of these GRBs through the closure relations within the time interval of the plateau emission. Finally, we test the 3D fundamental plane relation (Dainotti relation) which connects the prompt peak luminosity, the time at the end of the plateau (rest-frame), and the luminosity at that time, on the GRBs with redshift, concerning groups determined by the closure relations. This allows us to check if the intrinsic scatter \sigma_{int} of any of these groups is reduced compared to previous literature. The most fulfilled environments for the electron spectral distribution, p>2, are Wind Slow Cooling (SC) and ISM Slow Cooling for cases in which the parameter q, which indicates the flatness of the plateau emission and accounts for the energy injection, is =0 and =0.5, respectively, both in the cases with known and unknown redshifts. We also find that for the sGRBs All ISM Environments with $q=0$ have the smallest \sigma_{int}=0.04 \pm 0.15 in terms of the fundamental plane relation holding a probability of occurring by chance of p=0.005. We have shown that the majority of GRBs presenting the plateau emission fulfil the closure relations, including the energy injection, with a particular preference for the Wind SC environment. The subsample of GRBs that fulfil given relations can be used as possible standard candles and can suggest a way to reduce the intrinsic scatter of these studied relationships., Comment: 44 pages, 23 figures; Accepted to the PASJ to be published soon

We explore the morphology of Type Ia supernova remnants (SNRs) using three-dimensional hydrodynamics modeling and an exponential density profile. Our model distinguishes ejecta from the interstellar medium (ISM), and tracks the ionization age of shocked ejecta, both of which allow for additional analysis of the simulated remnants. We also include the adiabatic index as a free parameter, which affects the compressibility of the fluid and emulates the efficiency of cosmic ray acceleration by shock fronts. In addition to generating 3-D images of the simulations, we compute line-of-sight projections through the remnants for comparison against observations of Tycho's SNR and SN 1006. We find that several features observed in these two remnants, such as the separation between the fluid discontinuities and the presence of ejecta knots ahead of the forward shock, can be generated by smooth ejecta without any initial clumpiness. Our results are consistent with SN 1006 being dynamically younger than Tycho's SNR, and more efficiently accelerating cosmic rays at its forward shock. We conclude that clumpiness is not a necessary condition to reproduce many observed features of Type Ia supernova remnants, particularly the radial profiles and the fleecy emission from ejecta at the central region of both remnants., Comment: 17 pages, 13 figures, 4 tables, submitted to MNRAS

Mathematical models of stratospheric ozone have predicted a reduction in the total ozone due to chlorofluoromethanes released into the atmosphere. Analytical procedures for the collection of air in the stratosphere and for analysis of these air samples for trace levels of chlorine, regardless of the state of chemical composition were developed. Calibration experiments are conducted in order to validate all methods and procedures. Results of neutron activation analysis calibration procedures using standard chlorine gases are included.