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Study of astrophysics of black holes and neutron stars has taken a new turn in the present decade with the realization that sub-Keplerian flows and the associated centrifugal barrier near the horizon or the surface of a neutron star play a major role in deciding the nature of the emitted spectra and the formation of outflows from the accreting matter. This region may remain steady or oscillate depending on the accretion rate, specific angular momentum and specific energy of the flow. Intricacies of oscillation may depend on the degree of feedback the inflow receives from the outflow. This region may emit hard or soft X-rays depending on relative numbers of hot elections and soft photons intercepted by this region. We discuss how these properties come about and how they explain the observational results of black hole candidates.
Many black holes (BHs) detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) and the Virgo detectors are multiple times more massive than those in X-ray binaries. One possibility is that some BBHs merge within a few Schwarzschild
Despite the prevalence of jets in accreting systems and their impact on the surrounding medium, the fundamental physics of how they are launched and collimated is not fully understood. Radio observations of local compact objects, including accreting
The X-ray emission of neutron stars and black holes presents a rich phenomenology that can lead us to a better understanding of their nature and to address more general physics questions: Does general relativity apply in the strong gravity regime? Is
Accretion disks of active galactic nuclei (AGN) have been proposed as promising sites for producing both (stellar-mass) compact object mergers and extreme mass ratio inspirals. Along with the disk-assisted migration/evolution process, ambient gas mat
This article represents a short review of the variability characteristics of young stellar objects. Variability is a key property of young stars. Two major origins may be distinguished: a scaled-up version of the magnetic activity seen on main-sequen