Related papers: Self-Gravity in Magnetized Neutrino-Dominated Accr…
A nascent magnetar, accompanying a gamma-ray burst (GRB) explosion, releases enormous rotational energy via magnetic dipole radiation. The energy loss rate of the magnetar is determined by the strength of the magnetic field at the pole. We…
The equations governing the vertical structure of a stationary keplerian accretion disc are presented. The model is based on the alpha-viscosity, includes self-gravity, convective transport and turbulent pressure. A few properties of the…
Many models of gamma-ray bursts (GRBs) involve accretion onto a compact object, usually a black hole, at a mass accretion rate of order a fraction of a solar mass per second. If the accretion disk is larger than a few tens or hundreds of…
Magnetic fields play a dual role in gamma-ray bursts (GRBs). First, GRB and afterglow spectra (the latter interpreted as emission from external shocks) imply synchrotron radiation in a magnetic field that is a significant fraction of…
We present a systematic study on magnetic fields in Gamma-Ray Burst (GRB) external forward shocks (FSs). There are 60 (35) GRBs in our X-ray (optical) sample, mostly from Swift. We use two methods to study epsilon_B (fraction of energy in…
I review recent progresses in the dynamics and the evolution of self-gravitating accretion discs. Accretion discs are a fundamental component of several astrophysical systems on very diverse scales, and can be found around supermassive…
Early-time X-ray observations of GRBs with the Swift satellite have revealed a more complicated phenomenology than was known before. In particular, the presence of flaring activity on a wide range of time scales probably requires late-time…
We examine theoretically the behaviour of the inner accretion disk in GRS 1915+105 when soft X-ray dips are present in the X-ray light curve. We assume the presence of a radial shock in the accretion disk, as in some of the Two Component…
The central engine of gamma-ray bursts (GRBs) remains an open and forefront topic in the era of multimessenger astrophysics. The X-ray plateaus appear in some GRB afterglows, which are widely considered to originate from the spindown of…
A hyperaccreting stellar-mass black hole (BH) has been proposed as the candidate central engine of gamma-ray bursts (GRBs). Comparing the predictions from the central engine models with the temporal behavior of GRBs is of great interest. In…
GRB 170817A, detected by Fermi-GBM 1.7\,s after the merger of a neutron star (NS) binary, provides the first direct evidence for a link between such a merger and a short-duration gamma-ray burst. The X-ray observations after GRB 170817A…
The system of accretion disk and black hole is usually considered as the central engine of Gamma-ray Bursts (GRBs). It is usually thought that the disk in the central engine of GRBs is the advection-dominated accretion disk, which is…
Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes (BHs) have been theorized as the central engine of relativistic jets launched in massive star core collapse events or compact star mergers. In this work, we…
In the framework of a transient accretion disk at the core of a gamma-ray burst we compute possible periods of Lense-Thirring precession. Next, we evaluate the putative gravitational waves associated with such dynamical setup. Assuming a…
Hyper-accreting discs occur in compact-object mergers and collapsars, and may power gamma-ray bursts (GRBs). We calculate the microscopic viscosity and resistivity of plasma in these discs, and discuss the implications for their global…
Some fast radio bursts (FRBs) are expected to be associated with the afterglow emission of gamma-ray bursts (GRBs), while a short-lived, supermassive neutron star (NS) forms during the GRBs. I investigate the possible contributions to the…
In this paper, we have investigated the accreting millisecond X-ray pulsars, which are rapidly rotating neutron stars in low-mass X-ray binaries. These systems show coherent X-ray pulsations that arise when the accretion flow is…
The X-ray spectra of Active Galactic Nuclei (AGN) are complex and vary rapidly in time as seen in recent observations. Magnetic flares above the accretion disk can account for the extreme variability of AGN. They also explain the observed…
Disk accretion onto a neutron star possessing a weak surface magnetic field ($B \le 10^8$ G) provides interesting X-ray emission scenarios, and is relevant for understanding X-ray bursters and low-mass X-ray binaries (LMXBs). The standard…
We investigate long Gamma-Ray Bursts (GRB) which manifest a sharp linear rise followed by an exponential decay in their gamma-ray prompt emission observed with the BAT instrument on board the Swift satellite. We offer a simple…