Related papers: Prototyping non-equilibrium viscous-timescale accr…
Many statistical properties of X-ray aperiodic variability from accreting compact objects can be explained by the propagating fluctuations model applied to the accretion disc. The mass accretion rate fluctuations originate from variability…
We investigated the relation between compact jet emission and X-ray variability properties of all black hole transients with multiwavelength coverage during their outburst decays. We studied the evolution of all power spectral components…
In this chapter I will review the status of our phenomenological understanding of the relation between accretion and outflows in accreting black hole systems. This understanding arises primarily from observing the relation between X-ray and…
We present the results of axisymmetric, time-dependent magnetohydrodynamic simulations of accretion flows around black holes. The calculations begin from a rotationally supported thick torus which contains a weak poloidal field. Accretion…
Accreting black holes and neutron stars in their hard (low) state show not only very similar X/gamma-ray spectra but also that the behaviour of their light curves is quite similar which can be quantified as having similar power-density…
Theoretical studies of transonic accretion onto black holes reveal a wide range of possible solutions, broadly classified into smooth flows and flows featuring shocks. Accretion solutions that involve the formation of shocks are…
We have investigated the phenomenon of explosive chromospheric evaporation from an accretion disk as a mechanism for fast variability in accreting sources such as low mass X-ray binaries and active galactic nuclei. This has been done in the…
Blazars exhibit relentless variability across diverse spatial and temporal frequencies. The study of long- and short-term variability properties observed in the X-ray band provides insights into the inner workings of the central engine. In…
X-ray quasi-periodic oscillations (QPOs) are a characteristic feature of low-mass X-ray binaries (LMXBs). These oscillations have been studied for decades and revealed a rich and complex phenomenology that is still not fully understood.…
We have explored spectral line profiles due to spiral patterns in accretion discs around black holes. A parametrization was employed for the shape and emissivity of spiral waves, which can be produced by non-axisymmetric perturbations…
Numerical simulations of MHD accretion flows in the vicinity of a supermasssive black hole provide important insights to the problem of why and how systems -- such as the Galactic Center -- are underluminous and variable. To access…
We present the analysis of an RXTE monitoring campaign of the canonical soft state black hole candidates LMC X-1 and LMC X-3. In contrast to LMC X-1, which does not exhibit any periodic spectral changes, we find that LMC X-3 exhibits stron…
The evolution of the inner accretion flow of a black hole X-ray binary (BHXRB) during the outburst is still a matter of active research. X-ray reverberation lags are powerful tools to constrain the disk-corona geometry. We present a study…
We consider time-dependent models for rotating accretion flows onto black holes, where a transition takes place from an outer cooling-dominated disc to a radiatively inefficient flow in the inner region. In order to allow for a transition…
I review observations of the X-ray spectra of Galactic Black Hole Candidates, and theoretical ideas as to how these can be produced. X-ray reflection should enable different source geometries to be distinguished, but the ionisation…
The properties of the aperiodic brightness variability for the dwarf nova HL CMa are considered. The variability of the system HL CMa is shown to be suppressed at frequencies above $7\times10^{-3}$Hz. Different variability suppression…
Most black holes possess accretion disks. Models of such disks inform observations and constrain the properties of the black holes and their surrounding medium. Here, we study isothermal shocks in a thin black hole accretion flow. Modelling…
Accretion onto black holes often leads to the launch of outflows that significantly influence their surrounding environments. The two primary forms of these outflows are X-ray disk winds-hot, ionized gases ejected from the accretion…
We model the intermediate-mass black hole HLX-1, using the Hubble Space Telescope, XMM-Newton and Swift. We quantify the relative contributions of a bluer component, function of X-ray irradiation, and a redder component, constant and likely…
Variable features in black hole X-ray Binaries (BH-XRBs) are observed in different energy ranges and time scales. The physical origin of different spectral states in BH-XRBs and their relations with the underlying accretion disc are still…