Related papers: Modeling the Time Variability of Black Hole Candid…

Binary supermassive black holes (BSBHs) are expected to be a generic byproduct from hierarchical galaxy formation. The final coalescence of BSBHs is thought to be the loudest gravitational wave (GW) siren, yet no confirmed BSBH is known in…

Multiwavelength variability data, combined with spectral-timing analysis techniques, provides information about the causal relationship between different physical components in accreting black holes. Using fast-timing data and long-term…

The emission from galactic black holes and Seyfert galaxies is generally understood in term of two-phase models (Haardt and Maraschi 1991, 1993). Such models postulate that a hot plasma coexists with relatively colder material in the inner…

The connection of type-B QPOs to the hot flow in the inner accretion disk region is vaguely understood in black hole X-ray binaries. We performed spectral and timing studies of twenty-three observations where type-C and type-B QPOs with…

Relativistic outflows (mainly observed in the radio) are a characteristic feature of both Galactic stellar mass black holes and supermassive black holes (SMBHs). Simultaneous radio and X-ray observations of Galactic sources have shown that…

We have analysed X-ray outbursts from several Galactic black hole (GBH) transients, as seen by the ASM on board RXTE. We have used the best estimates of distance and black hole mass to find their luminosity (scaled to the Eddington limit),…

We present a framework to link and describe AGN variability on a wide range of timescales, from days to billions of years. In particular, we concentrate on the AGN variability features related to changes in black hole fuelling and accretion…

We analyze the light curves of 413 radio sources at submillimeter wavelengths using data from the Submillimeter Array calibrator database. The database includes more than 20,000 observations at 1.3 and 0.8 mm that span 13 years. We model…

Recoiling supermassive black holes (SMBHs) are considered one plausible physical mechanism to explain high velocity shifts between narrow and broad emission lines sometimes observed in quasar spectra. If the sphere of influence of the…

We analyse the properties of the Comptonizing medium in the black-hole X-ray binary Swift J1727.8$-$1613 using the time-dependent Comptonization model vkompth, using NICER observations of type-C QPOs in the hard and hard-intermediate…

The so-called memory-burden effect implies that evaporating Primordial Black Holes (PBHs) inevitably stabilize before complete decay. This stabilization opens a new mass window for PBH Dark Matter below $10^{15}\,$g. The transition to the…

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…

Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic, can be due to a variety of physical mechanisms, and is well-described statistically in terms of a damped random walk model. The…

Quasars emission is highly variable, and this variability gives us clues to understand the accretion process onto supermassive black holes. We can expect variability properties to correlate with the main physical properties of the accreting…

There have been a number of recent spectral models that have been successful in reproducing the observed X-ray spectra of galactic black hole candidates (GBHC). However, there still exists controversy over such issues as: what are the…

If light enough primordial black holes (PBH) account for dark matter, then its density decreases with time as they lose mass via Hawking radiation. We show that this time-dependence of the matter density can be formulated as an equivalent…

The X-ray variations of hard state black hole X-ray binaries above 2 keV show 'hard lags', in that the variations at harder energies follow variations at softer energies, with a time-lag \tau depending on frequency \nu approximately as \tau…

We study the high-energy emission of the Galactic black hole candidate GX 339-4 using INTEGRAL/SPI and simultaneous RXTE/PCA data. By the end of January 2007, when it reached its peak luminosity in hard X-rays, the source was in a bright…

Thanks for the releasing image of supermassive black holes (BHs) by the event horizon telescope (EHT) at the heart of the $M87$ galaxy. After the discovery of this mysterious object, scientists paid attention to exploring the BH shadow…

We present time-dependent simulations of a two-phase accretion flow around a black hole. The accretion flow initially is composed of an optically thick and cool disc close to the midplane, while on top and below the disc there is a hot and…