Related papers: Delayed X-ray emission from fallback in compact-ob…
The afterglows to gamma-ray bursts (GRBs) are due to synchrotron emission from shocks generated as an ultra-relativistic outflow decelerates. A forward and a reverse shock will form, however, where emission from the forward shock is well…
The discovery of long-lasting (~100 s) X-ray flares following short gamma-ray bursts initially called into question whether they were truly classical short-hard bursts. Opinion over the last few years has coalesced around the view that the…
GRB 250221A is a short gamma-ray burst (GRB) at redshift $z=0.768$, with a duration of 1.8 s and no extended emission in either Swift/Burst Alert Telescope or Konus-Wind bands. A remarkable rebrightening feature in both optical and X-ray…
The recent observations of GW170817 and its electromagnetic (EM) counterparts show that double neutron star mergers could lead to rich and bright EM emissions. Recent numerical simulations suggest that neutron star and neutron star/black…
Compact remnants -- stellar mass black holes and neutron stars formed in the inner few parsec of galactic centres are predicted to sink into the central parsec due to dynamical friction on low mass stars, forming a high concentration cusp…
Neutron star binary mergers are strong sources of gravitational waves (GWs). Promising electromagnetic counterparts are short gamma-ray bursts (GRBs) but the emission is highly collimated. We propose that the scattering of the long-lasting…
Binary neutron star (NS) mergers may result in remnants of supra-massive or even stable NS, which have been supported indirectly by observed X-ray plateau of some gamma-ray bursts (GRBs) afterglow. Recently, Xue et al. (2019) discovered a…
We have identified a merging galaxy cluster with evidence of two distinct sub-clusters. The X-ray and optical data suggest that the subclusters are moving away from each other after closest approach. This cluster merger was discovered from…
A subset of short gamma-ray bursts (sGRBs) have been found to be characterized by near-infrared/optical bumps at $\sim 1$ days, some of which exhibit almost concurrent X-ray flares. Although the near-infrared/optical bumps may be a…
The binary neutron star (BNS) merger GW170817 was the first astrophysical source detected in gravitational waves and multi-wavelength electromagnetic radiation. The almost simultaneous observation of a pulse of gamma-rays proved that BNS…
The fraction of long duration gamma ray bursts (GRBs) without an associated bright supernovae (SNe) at small redshifts $(z<0.15)$ is comparable to that of GRBs associated with SNe. We show, that their X-ray afterglow and the X-ray afterglow…
In this work, we investigate gravitational-wave signatures of a proposed subsolar-mass merger scenario resulting from fragmentation inside a collapsar accretion disk. This scenario has gained recent interest with the electromagnetic…
Galactic nuclei are densely populated by stellar mass compact objects such as black holes and neutron stars. Bound, highly eccentric binaries form as a result of gravitational wave (GW) losses during close flybys between these objects. We…
The recent detections of the $\sim10$-s long $\gamma$-ray bursts (GRBs) 211211A and 230307A followed by softer temporally extended emission (EE) and kilonovae, point to a new GRB class. Using state-of-the-art first-principles simulations,…
The coalescence of supermassive black hole binaries occurs via the emission of gravitational waves, that can impart a substantial recoil to the merged black hole. We consider the energy dissipation, that results if the recoiling black hole…
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…
A binary neutron star (BNS) merger has been widely argued to be one of the progenitors of a short gamma-ray burst (SGRB). This central engine can be verified if its gravitational-wave (GW) event is detected simultaneously. Once confirmed,…
Short gamma-ray bursts (SGRBs) are now known to be the product of the merger of two compact objects. However, two possible formation channels exist: neutron star -- neutron star (NS -- NS) or NS -- black hole (BH). The landmark SGRB 170817A…
In addition to producing a strong gravitational signal, a short gamma-ray burst (GRB), and a compact remnant, neutron star mergers eject significant masses at significant kinetic energies. This mass ejection takes place via dynamical mass…
This chapter discusses the implications of X-ray binaries on our knowledge of Type Ibc and Type II supernovae. X-ray binaries contain accreting neutron stars and stellar--mass black holes which are the end points of massive star evolution.…