Related papers: Polarization Signatures from GRMHD Simulations of …
This dissertation is written as an annotated collection of selected articles. The dissertation focuses on the modelling of accretion disks in X-ray binaries with a black hole or neutron star. The main objective is to use advanced numerical…
While Albert Einstein's theory of General Relativity (GR) has been tested extensively in our solar system, it is just beginning to be tested in the strong gravitational fields that surround black holes. As a way to study the behavior of…
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…
Current astrophysical research suggests that the most persistently luminous objects in the Universe are powered by the flow of matter through accretion disks onto black holes. Accretion disk systems are observed to emit copious radiation…
Accretion physics studies the process of gravitational capture of ambient matter by massive stars. The background processes are very challenging to observe and measure due to the extreme conditions in these systems. Numerical simulations…
Several massive black holes exhibit flux variability on time scales that correspond to source sizes of the order of few Schwarzschild radii. We survey the potential of near-infrared and X-ray polarimetry to constrain physical properties of…
The effects of strong gravity on the polarization of the Compton reflection from an X-ray illuminated accretion disc are studied. The gravitational field of a rotating black hole influences Stokes parameters of the radiation along the…
X-ray binaries are known to exhibit different spectral states which are often associated with different black hole accretion modes. The exact geometry and properties of these accretion modes is still uncertain. Recent IXPE measurements of…
We present new calculations of X-ray polarization from black hole accretion disks in the thermally-dominated state, using a Monte-Carlo ray-tracing code in full general relativity. In contrast to many previously published studies, our…
We discuss properties of thermal and hybrid (thermal/non-thermal) electron-positron plasmas in the pair and energy equilibria. Various accretion disc-corona models, recently proposed to explain properties of galactic as well as…
Accreting neutron stars differ from black holes by the presence of the star's own magnetic field, whose interaction with the accretion flow is a central component in understanding these systems' disk structure, outflows, jets, and spin…
We briefly review a fruitful approach to compute a variety of radiation signatures of General Relativity (GR) originating from accretion disks in strong gravity. A set of transfer functions can be pre-computed and then employed to…
Measurements of the angular momentum (spin) of astrophysical black holes are extremely important, as they provide information on the black hole formation and evolution. We present simulated observations of a X-ray binary system with the…
X-ray binaries, as bright local sources with short variability timescales for a wide range of accretion processes, represent ideal targets for high-resolution X-ray spectroscopy. In this chapter, we present a high-resolution X-ray spectral…
Large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer ({IXPE}) in the high-soft emission state of the black hole X-ray binary 4U 1630--47. The highly significant detection (at…
We summarize results from a survey of radiation-dominated black hole accretion flows across a wide range of mass accretion rates, as well as two values of black hole spin and initial magnetic field geometry. These models apply an algorithm…
Magnetic fields are believed to drive accretion and relativistic jets in black hole accretion systems, but the magnetic-field structure that controls these phenomena remains uncertain. We perform general relativistic (GR) polarized…
In this paper we report on recent upgrades to our general relativistic radiation magnetohydrodynamics code, Cosmos++, including the development of a new primitive inversion scheme and a hybrid implicit-explicit solver with a more general…
The X-ray polarimetric observing window re-opening is shedding new light on our current understanding of compact accreting sources. This is true, in particular, for stellar-mass black hole sources observed in the thermally-dominated state,…
The accretion-ejection activities of black holes play a vital role in shaping the Universe. Bright and recurrent black hole X-ray binaries are ideal objects for studying accretion physics across a wide range of accretion rates, providing…