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An accretion flow onto a supermassive black hole is the primary process powering quasars. However, a geometry of this flow is not well constrained. Both global MHD simulations and observations suggest that there are several emission…

宇宙学与河外天体物理 · 物理学 2012-03-08 Aneta Siemiginowska

Rapidly growing black holes are surrounded by accretion disks that make them the brightest objects in the Universe. Their brightness is known to be variable, but the causes of this are not implied by simple disk models and still debated.…

星系天体物理 · 物理学 2024-02-26 Ji-Jia Tang , Christian Wolf , John Tonry

Hard X-ray emission is ubiquitous in accreting black holes, both in Galactic binary systems and in Active Galactic Nuclei. I review the different spectra which can be seen from these systems, and possible ways of producing this emission.…

天体物理学 · 物理学 2007-05-23 Chris Done

Here we investigate the connection of broad emission line shapes and continuum light curve variability time scales of type-1 Active Galactic Nuclei (AGN). We developed a new model to describe optical broad emission lines as an accretion…

星系天体物理 · 物理学 2018-05-21 E. Bon , P. Jovanovic , P. Marziani , N. Bon , A. Otasevic

We study the optical variability characteristics of Active Galactic Nuclei (AGN) from the Swift Burst Alert Telescope (BAT) AGN catalogue by utilising approximately five years of optical light curves from the Zwicky Transient Facility (ZTF)…

高能天体物理现象 · 物理学 2025-08-12 Vivek Kumar Jha , Debbijoy Bhattacharya , Hum Chand

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…

高能天体物理现象 · 物理学 2017-09-01 A. N. Semena , M. G. Revnivtsev , T. I. Larchenkova , A. A. Lutovinov

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…

高能天体物理现象 · 物理学 2015-06-04 W. Ishibashi , T. J. -L. Courvoisier

Accretion disks around supermassive black holes are widely believed to be the dominant source of the optical-ultraviolet continuum in many classes of active galactic nuclei (AGN). We study here the relationship between the continuum colors…

天体物理学 · 物理学 2011-02-11 E. W. Bonning , L. Cheng , G. A. Shields , S. Salviander , K. Gebhardt

Recently, it has been shown that soft-state black hole X-ray binaries and active galactic nuclei populate a plane in the space defined by the black hole mass, accretion rate and characteristic frequency. We show that this plane can be…

天体物理学 · 物理学 2009-11-13 E. G. Koerding , S. Migliari , R. Fender , T. Belloni , C. Knigge , I. McHardy

A critical review is presented of the current status of our understanding of the the spectral output of thermally-radiating accretion disks around black holes, with special attention to those around supermassive black holes in active…

天体物理学 · 物理学 2007-05-23 J. H. Krolik

How black holes accrete surrounding matter is a fundamental, yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the…

Observations of Galactic black hole sources are traditionally done in the classical X-ray range (2 -- 10 keV) due to sensitivity constraints. Most of the accretion power, however, is radiated above 10 keV and the study of these sources in…

高能天体物理现象 · 物理学 2013-10-02 A. R. Rao

Accretion onto supermassive black holes produces both the dramatic phenomena associated with active galactic nuclei and the underwhelming displays seen in the Galactic Center and most other nearby galaxies. I review selected aspects of the…

天体物理学 · 物理学 2016-01-27 Philip J. Armitage

Geometrically thick disks may form after tidal disruption events, and rapid accretion may lead to short flares followed by long-term, lower-level emission. Using a novel accretion disk code which relies primarily on global conservation laws…

天体物理学 · 物理学 2007-05-23 Andrew Ulmer

The variability of the Fe K alpha line near 6.5 keV seems to be reduced compared to the variability of the hard X-rays which presumably drive the line emission. This is observed both in active galactic nuclei and galactic black hole…

天体物理学 · 物理学 2016-08-30 P. T. Zycki

Accretion onto black holes often proceeds via an accretion disk or a temporary disk-like pattern. Variability features observed in light curves as well as theoretical models of accretion flows suggest that accretion disks tend to be…

高能天体物理现象 · 物理学 2018-08-03 V. Karas , Y. Kojima , D. Kunneriath

We present a model for the short timescale spectral variability of accreting black holes. It describes well the time-averaged spectra as well as temporal characteristics such as power-density spectrum, time/phase lags, and coherence…

天体物理学 · 物理学 2009-10-31 Juri Poutanen , Andrew C. Fabian

The variability of submillimeter emission provides a useful tool to probe the accretion physics in low-luminosity active galactic nuclei. We accumulate four years of observations using Submillimeter Array for Centaurus A, NGC 4374, NGC…

Traditionlly, gravitational wave emission from a coalescing binary system is computed using point mass approximations without considering any accretion disk. However, it is believed that in many of the galactic nuclei, there are…

天体物理学 · 物理学 2007-05-23 Sandip K. Chakrabarti