Related papers: Modeling the Time Variability of Black Hole Candid…
We present model light curves for accreting Black Hole Candidates (BHC) based on a recently proposed model for their spectro-temporal properties. According to this model, the observed light curves and aperiodic variability of BHC are due to…
We present a model for the aperiodic variablity of accreting Black Hole Candidates (BHC) along with model light curves. According to the model this variability is the combined outcome of random (Poisson) injection of soft photons near the…
I review the temporal/spectral data of accreting black hole sources paying most attention to the properties of the temporal variability such as photon energy dependent auto- and cross-correlation functions, average shot profiles and…
We exhibit, by compiling all data sets we can acquire, that the Fourier frequency dependent hard X-ray lags, first observed in the analysis of aperiodic variability of the light curves of the black hole candidate Cygnus X-1, appear to be a…
X-ray variability of active galactic nuclei (AGN) and black hole binaries can be analysed by means of the power spectral density (PSD). The break observed in the power spectrum defines a characteristic variability timescale of the accreting…
The Temporal and Spectral variations of black hole candidates during outbursts have been reported in several publications. It is well known that during an outburst, the source becomes soft in the first few days, and then returns to the hard…
The time-dependent Comptonized output of a cool soft X-ray source drifting inward through an inhomogeneous hot inner disk or corona is numerically simulated. We propose that this scenario can explain from first principles the observed…
We investigate the effect of inverse-Compton scattering of flares of soft radiation in different geometries of a hot, Comptonizing region and a colder accretion disk around a solar-mass black hole. The photon-energy dependent light curves,…
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…
We have found relations between the temporal and spectral properties of radiation Comptonized in an extended atmosphere associated with compact accreting sources. We demonstrate that the fluctuation power spectrum density (PSD) imposes…
We develop new techniques to deconvolve the radial structure of the X-ray emission region in the bright low/hard state of the black hole Cygnus X-1 using both spectral and timing data in the 3-35~keV range. The spectrum at these energies is…
Temporal and spectral variations of black hole candidates during outbursts have been reported in several publications. It is well known that during an outburst, source becomes softer in first few days, and then returns to hard states after…
I review the observed temporal X-ray properties of Galactic black hole candidates and the status of theoretical modeling of these properties. Like spectral X-ray properties, which has so far attracted most of the attention, the temporal…
The Fourier frequency dependent hard X-ray lag, first discovered from the analysis of aperiodic variability of the light curves of the black hole candidate Cygnus X-1, turns out to be a property shared by several other accreting compact…
Most black hole candidates exhibit characteristic power-law like hard X-ray emission above $\sim$ 10 keV. In the {\em high state}, in which 2 -- 10 keV luminosity is relatively high, the energy index of the hard X-ray emission is usually…
The ``low'' (hard or ``non-thermal'') state of black hole candidates is sometimes modelled via an optically thick, hot Compton cloud that obscures a softer input source such as an accretion disk. In these models the observed output spectra…
Hot spots residing on the surface of an accretion disc have been considered as a model of short-term variability of active galactic nuclei. In this paper we apply the theory of random point processes to model the observed signal from an…
We study the energy dependent photon variability from a thermal Comptonizing plasma that is oscillating at kHz frequencies. In particular, we solve the linearised time dependent Kompaneets equation and consider the oscillatory perturbation…
We build a full spectral-timing model for the low/hard state of black hole binaries assuming that the spectrum of the X-ray hot flow can be produced by two Comptonisation zones. Slow fluctuations generated at the largest radii/softest…
To better constrain the emission mechanism underlying the hard state of galactic black hole candidates, we use high-time resolution RXTE lightcurves for Cyg X-1 and GX 399-4 to compute two higher order variability statistics for these…