Related papers: Compact Objects and Accretion Disks
The thesis studies the X-ray emission from the Galactic compact objects (accreting neutron stars and black holes), using mainly the RXTE data. In particular following results have been included: spectral evolution of X-ray transients GRS…
The study of radiation emitted from black hole accretion discs represents a crucial way to understand the main physical properties of these sources, and in particular the black hole spin. Beside spectral analysis, polarimetry is becoming…
Although the black holes are an integral part of the standard model of astrophysics and cosmology, their existence poses some serious fundamental problems. In recent years, several horizonless compact object models were proposed to address…
A common question about compact objects in high energy astrophysics is whether it is possible to distinguish black hole from neutron star systems with some other property that is not the mass of the compact object. Up to now a few…
Black holes are the most compact objects in the Universe. According to general relativity, black holes have a horizon that hides a singularity where Einstein's theory breaks down. Recently, gravitational waves opened the possibility to…
Black holes are by definition black, and therefore cannot be directly observed by using electromagnetic radiations. Convincing identification of black holes must necessarily depend on the identification of a very specially behaving matter…
Accretion onto black holes often proceeds via an accretion disk or a temporary disk-like pattern. Variability features observed in light curves as well as theoretical models of accretion flows suggest that accretion disks tend to be…
I analyse the relativistic accretion phenomena around rotating black holes and neutron stars in pseudo-Newtonian approach and show both the kinds of disk can be treated in an unified manner. For this purpose, number of pseudo-Newtonian…
This paper reviews the current understanding of double neutron star and neutron star black hole binaries. It addresses mainly (nuclear) astrophysics aspects of compact binary mergers and thus complements recent reviews that have emphasized…
This article reviews the current status of black hole astrophysics, focusing on topics of interest to a physics audience. Astronomers have discovered dozens of compact objects with masses greater than 3 solar masses, the likely maximum mass…
The geometry of black hole spacetimes can be probed with exquisite precision in the gravitational-wave window, and possibly also in the optical regime. We study the accretion of bright spots -- objects which emit strongly in the optical or…
A solid theoretical understanding of how inflowing, accreting plasma around black holes and other compact objects gives rise to outflowing winds and jets is still lacking, despite decades of observations. The fact that similar processes and…
In this review, I summarize the main X-ray/hard X-ray properties of the accretion flows around black holes and neutron stars based on recent broad-band spectral and timing observations performed by the BeppoSAX and Rossi X-ray Timing…
In recent decades, the relevance of polarimetry in planetary sciences and astronomy has increased rapidly. Polarization is a fundamental property of light and can be modified by any scattering event. As such, polarization yields additional…
This article is intended to provide a pedagogical account of issues related to, and recent work on, gravitational waves from coalescing compact binaries (composed of neutron stars and/or black holes). These waves are the most promising for…
The recent observations of neutron star mergers have changed our perspective on scalar- tensor theories of gravity, favouring models where gravitational waves travel at the speed of light. In this work we consider a scalar-tensor set-up…
The visual distortion effects visible to an observer traveling around and descending to the surface of an extremely compact star are described. Specifically, trips to a ``normal" neutron star, a black hole, and an ultracompact neutron star…
We perform a search for stellar-mass black hole candidates in the spatial regions with increased probability of their occurrence, isolated based on the evolutionary scenarios for compact objects originating in disrupted binaries. We analyze…
Black-hole spectroscopy is a powerful tool to probe the Kerr nature of astrophysical compact objects and their environment. The observation of multiple ringdown modes in gravitational waveforms could soon lead to high-precision…
Black holes are the most compact objects in the universe. Therefore, matter accreting onto is likely to radiate photons of energy comparable to very high gravitational potential energy. We discuss the nature of the emitted radiation in…