Related papers: Chemical Evolution and Kilonova Implications of Po…
We study the structure and evolution of the accreting plasma in gamma ray burst central engines. The models are based on the general relativistic MHD simulations. The nuclear equation of state adequate for dense and degenerate plasma, is…
A compact accretion disk may be formed in the merger of two neutron stars or of a neutron star and a stellar-mass black hole. Outflows from such accretion disks have been identified as a major site of rapid neutron-capture (r-process)…
Along with binary neutron star mergers, the in-spiral and merger of a black hole and a neutron star is a predicted site of $r$-process nucleosynthesis and associated kilonovae. For the right mass ratio, very large amounts of neutron rich…
Rapid, hyper-Eddington accretion is likely to power the central engines of gamma-ray bursts (GRBs). In the extreme conditions of densities and temperatures the accreting torus is cooled by neutrino emission rather than by radiation. Another…
Remnant accretion disks formed in compact object mergers are an important ingredient in the understanding of electromagnetic afterglows of multi-messenger gravitational-wave events. Due to magnetically and neutrino driven winds, a…
We suggest that part of the infalling material during the core-collapse of a massive star goes into orbit around the compact core to form a hot, dense, centrifugally-supported accretion disk whose evolution is strongly influenced by…
The merger of binary neutron stars, or of a neutron star and a stellar-mass black hole, can result in the formation of a massive rotating torus around a spinning black hole. In addition to providing collimating media for gamma-ray burst…
We report results from simulations in general relativity of magnetized disks accreting onto merging black hole binaries, starting from relaxed disk initial data. The simulations feature an effective, rapid radiative cooling scheme as a…
We follow the nuclear reactions that occur in the accretion disks of stellar mass black holes that are accreting at a very high rate, 0.01 to 1 solar masses per second, as is realized in many current models for gamma-ray bursts (GRBs). The…
Gamma-Ray Burst (GRB) prompt and afterglow emission, as well as a kilonova (KN), are the expected electromagnetic (EM) counterparts of Binary Neutron Star (BNS) and Neutron Star -- Black Hole (NSBH) mergers. We aim to infer the KN ejecta…
We consider the gamma ray burst (GRB) central engine that is powered by the collapse of a massive rotating star or compact binary merger. The engine is a hot and dense accretion disk, which is composed of free nucleons, electron-positron…
The ultrarelativistic jets responsible for prompt and afterglow emission in gamma ray bursts are presumably driven by a central engine that consists of a dense accretion disk around a spinning black hole. We consider such engine, composed…
We investigate $r$-process nucleosynthesis and kilonova emission resulting from binary neutron star (BNS) mergers based on a three-dimensional (3D) general-relativistic magnetohydrodynamic (GRMHD) simulation of a hypermassive neutron star…
Black hole-torus systems from compact binary mergers are possible engines for gamma-ray bursts (GRBs). During the early evolution of the post-merger remnant, the state of the torus is determined by a combination of neutrino cooling and…
Rapidly spinning, strongly magnetized proto-neutron stars ("millisecond proto-magnetars") are candidate central engines of long-duration gamma-ray bursts (GRB), superluminous supernovae (SLSNe), and binary neutron star mergers. Magnetar…
We examine the long-term evolution of accretion tori around black hole (BH) remnants of compact object mergers involving at least one neutron star, to better understand their contribution to kilonovae and the synthesis of r-process…
Recently, a kilonova-associated gamma-ray burst (GRB 211211A), whose light curve consists of a precursor ($\sim$0.2 s), a hard spiky emission ($\sim$10 s), and a soft long extended emission ($\sim$40 s), has attracted great attention.…
Context. The coincident detection of GW170817 and GRB170817A marked a milestone for the connection between binary neutron star (BNS) mergers and short gamma-ray bursts (sGRBs). These mergers can lead to the formation of a black hole…
Mergers of binary neutron stars (NSs) usually result in the formation of a hypermassive neutron star (HMNS). Whether- and when this remnant collapses to a black hole (BH) depends primarily on the equation of state and on angular momentum…
We consider a jet-disk symbiosis model to explain Gamma Ray Bursts and their afterglows. It is proposed that GRBs develop in a pre-existing jet. We consider a binary system formed by a neutron star and an O/B/WR companion in which the…