Related papers: Solving the gamma-ray radiative transfer equation …
We derive new constraints on light CP-even scalars using old gamma-ray observations in the direction of SN1987A by the Solar Maximum Mission (SMM) satellite. Light scalars can be abundantly produced in the supernova core via the nucleon…
Binary neutron star mergers are expected to produce fast dynamical ejecta, with mildly relativistic velocities extending to $\beta=v/c>0.6$. We consider the radio to X-ray synchrotron emission produced by collisionless shocks driven by such…
AAssociation of GW170817/GRB170817A/AT2017gfo provides the first direct evidence for neutron star mergers as significant sources of $r$-process nucleosynthesis. A gamma-ray transient (GRT) would be powered by the radioactive decay of the…
We present a new multi-dimensional radiation-hydrodynamics code for massive stellar core-collapse in full general relativity (GR). Employing an M1 analytical closure scheme, we solve spectral neutrino transport of the radiation energy and…
Accurate radiative transfer coefficients (emissivities, absorptivities, and rotativities) are needed for modeling radiation from relativistically hot, magnetized plasmas such as those found in Event Horizon Telescope sources. Here we…
Observations and theoretical calculations have shown the importance of non-spherically symmetric structures in supernovae. Thus, the interpretation of observed supernova spectra requires the ability to solve the transfer equation in 3-D…
The hypothetical massive dark photon ($\gamma'$) which has kinetic mixing with the SM photon can decay electromagnetically to $e^+e^-$ pairs if its mass $m$ exceeds $2m_e$ and otherwise into three SM photons. These decays yield cosmological…
We present results of a calculation of absorption of 10-500 GeV gamma-rays at high redshifts. This calculation requires the determination of the high- redshift evolution of the full spectral energy distribution of the intergalactic photon…
The intensities of the ten strongest $\gamma$-ray transitions following the $^{111}Sn$ ($T_{1/2}$=35.3 m) decay have been determined via comparison of the two sets of the experimental photonucleon reaction yields driven using the…
The emission of the 4.438-MeV gamma-ray line in proton inelastic scattering off 12C has been investigated in detail. The correlated scattering and emission process is described independently for the direct reaction mechanism and for the…
Neutron star mergers are cosmic catastrophes that produce some of the most energetic observed phenomena: short gamma-ray bursts, gravitational wave signals, and kilonovae. The latter are optical transients, powered by radioactive nuclides…
We develop a method of analyzing radio frequency spectral line observations to derive data on the temperature, density, velocity, and molecular abundance of the emitting gas. The method incorporates a radiative transfer code with a new…
Supernovae (SNe) exploding in a dense circumstellar medium (CSM) are predicted to accelerate cosmic rays in collisionless shocks and emit GeV gamma rays and TeV neutrinos on a time scale of several months. Here we summarize the results of…
The most promising astrophysical sources of kHz gravitational waves (GWs) are the inspiral and merger of binary neutron star(NS)/black hole systems. Maximizing the scientific return of a GW detection will require identifying a coincident…
The brief transient emitted as a shock wave erupts through the surface of a presupernova star carries information about the stellar radius and explosion energy. Here the CASTRO code, which treats radiation transport using multigroup…
Red supergiants may experience a short-lived period of episodic mass loss rather than steady winds before their core collapses, leading to dense circumstellar matter (CSM) close to core-collapse supernovae (SNe). Interaction of SN ejecta…
Observations of some supernovae (SNe), such as SN 2014C, in the X-ray and radio wavebands revealed a rebrightening over a timescale of about a year since their detection. Such a discovery hints towards the evolution of a hydrogen-poor SN of…
Supernova remnants have long been considered as a promising candidate for sources of Galactic cosmic rays. However, modelling cosmic-ray transport around these sources is complicated by the fact that the overdensity of cosmic rays close to…
This thesis is devoted to the analysis of X-ray observations of supernova remnants (SNRs), exploiting the diagnostic potential provided by X-ray spectroscopy and complementing it with the synthesis of X-ray observables from…
Explosions of type Ic supernovae (SNe Ic) are investigated using a relativistic hydrodynamic code to study roles of their outermost layers of the ejecta in light element nucleosynthesis through spallation reactions as a possible mechanism…