Related papers: Modeling the Time Variability of Black Hole Candid…
We present a Comptonization model for the observed properties of the energy-dependent soft/hard time lags and pulsed fraction (amplitude) associated with the pulsed emission of a neutron star (NS). We account for the soft lags by…
We study the time variability and spectral evolution of the Black Hole Candidate source XTE J1650-500 using the BeppoSax wide energy range (0.12-200 keV) observations performed during the 2001 X-ray outburst. The source evolves from a…
Most, probably all, accreting binaries that are believed to contain a black-hole emit radio waves when they are in the low/hard state. Whenever this radio emission has been resolved, a jet-like structure has become apparent. We propose that…
In this work we have developed a new stochastic model for the fluctuations in lightcurves of accreting black holes. The model is based on a linear combination of stochastic processes and is also the solution to the linear diffusion equation…
Low mass X-ray binaries (LMXBs) show strong variability over a broad range of time scales. The analysis of this variability, in particular of the quasi-periodic oscillations (QPO), is key to understanding the properties of the innermost…
Accreting black hole sources show a wide variety of rapid time variability, including the manifestation of time lags during X-ray transients, in which a delay (phase shift) is observed between the Fourier components of the hard and soft…
On the basis of data from an energy-conserving 3D general relativistic MHD simulation, we predict the statistical character of variability in the coronal luminosity from accreting black holes. When the inner boundary of the corona is…
The theoretical predictions of the converging inflow, or Bulk-Motion Comptonization model are discussed and some predictions are compared to X- and gamma-ray observations of the high/soft state of Galactic black hole candidate XTE…
X-ray variability of accreting black hole binaries is believed to be produced by the fluctuations propagating towards the compact object. Observations suggest the light curves in different energy bands are connected, but the fluctuations at…
We present calculations of the time lags and the coherence function of X-ray photons for a novel model of radiation emission from accretion powered, high-energy sources. Our model involves only Comptonization of soft photons injected near…
Long-term observations have shown that black hole X-ray binaries exhibit strong, aperiodic variability on time-scales of a few milliseconds to seconds. The observed light curves display various characteristic features like a log-normal…
Bulk motion Comptonization utilizes properties of both matter and radiation close to the horizon of a black hole. Computation with these considerations produce hard tails of energy spectral slope $\sim 1.5-1.7$. These are the most direct…
X-Ray time lag of black hole candidates contains important information regarding the emission geometry. Recently, study of time lags from observational data revealed very intriguing properties. To investigate the real cause of this lag…
The fluctuating accretion model of Lyubarskii (1997) and its extension by Kotov et al. (2001), seeks to explain the spectral-timing properties of the X-ray variability of accreting black holes in terms of inward-propagating mass accretion…
We study Compton upscattering of low-frequency photons in a converging flow of thermal plasma. The photons escape diffusively and electron scattering is the dominant source of opacity. We solve numerically and approximately analytically the…
The nature of lag variation of Galactic black holes remains enigmatic mostly because of nonlinear and non-local physical mechanisms which contribute to the lag of the photons coming from the region close to the central black holes. One of…
We present a new release of the RELTRANS model to fit the complex cross-spectrum of accreting black holes as a function of energy. The model accounts for continuum lags and reverberation lags self-consistently in order to consider the…
The strong variability of blazars can be characterized by power spectral densities (PSDs) and Fourier frequency-dependent time lags. In previous work, we created a new theoretical formalism for describing the PSDs and time lags produced via…
The properties of the aperiodic variability in X-ray binaries with black holes are considered. The power spectra of the luminosity variability for a flat accretion disk that is an emission source with a power-law energy spectrum have been…
Accretion onto supermassive black holes (SMBHs) in realistic halos is time-variable, governed by turbulence, cooling, and multiphase condensation. In chaotic cold accretion (CCA), clouds and filaments condense out of the hot gas and feed…