scholarly journals Strong Gravity and X-ray Spectroscopy

1999 ◽  
pp. 231-240 ◽  
Author(s):  
A. Maciołek-Niedźwiecki ◽  
P. Magdziarz
Keyword(s):  
X Ray ◽  
Strong Gravity

scholarly journals Evidence for Strong Gravity in the AGN Plasmas

1998 ◽  
Vol 188 ◽  
pp. 141-144
Author(s):  
K. Iwasawa
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Relativistic Effects ◽  
Iron Line ◽  
X Ray ◽  
Strong Gravity

X-ray spectroscopy of the broad iron line has revealed some relativistic effects caused by strong gravity about a black hole in active galactic nuclei (AGN). Recent results from ASCA observations of AGNs are reviewed.

scholarly journals EFFECTS OF KERR STRONG GRAVITY ON QUASAR X-RAY MICROLENSING

2013 ◽  
Vol 769 (2) ◽  
pp. 131 ◽  
Author(s):  
Bin Chen ◽  
Xinyu Dai ◽  
E. Baron ◽  
R. Kantowski
Keyword(s):  
X Ray ◽  
Strong Gravity

scholarly journals Small-Scale Structure Deduced from X- and γ-ray Timing Measurements

2001 ◽  
Vol 205 ◽  
pp. 244-251
Author(s):  
M. Coleman Miller
Keyword(s):  
Black Holes ◽  
Neutron Stars ◽  
Small Scale ◽  
Large Area ◽  
X Ray ◽  
Strong Gravity ◽  
Thermonuclear Burning ◽  
General Relativistic ◽  
Γ Ray ◽  
Area X

X-ray timing observations of neutron stars and black holes are among the few available probes of ultrastrong magnetic fields, strong gravity, high densities, and the propagation of thermonuclear burning. Here we review the evidence for these effects revealed with data from the Rossi Explorer in the last five years. We also discuss the exciting prospects for making the first quantitative tests of strong-gravity general relativistic predictions with a large-area X-ray timing mission.

MATTER UNDER STRONG GRAVITY: THE NUCLEAR REGIONS OF AGN

2004 ◽  
Vol 13 (07) ◽  
pp. 1509-1518
Author(s):  
THOMAS BOLLER
Keyword(s):  
Power Law ◽  
Physical Nature ◽  
Seyfert Galaxies ◽  
X Ray ◽  
Strong Gravity ◽  
Nuclear Regions ◽  
Characteristic Features ◽  
Low X ◽  
New Generation ◽  
Hot Corona

X-ray observations of Seyfert galaxies and quasars currently provide the most powerful way to study the environments of supermassive black holes. Our ability to probe these environments, some of the most extreme found in nature, is rapidly improving driven by dramatic advances in X-ray spectroscopic instrumentation. In addition to the well known 'hard X-ray power law' that is probably formed in a hot 'corona' above a cooler accretion disc, substantial spectral complexity has also been revealed. For example, soft X-ray excess emission above the power law is often seen at low X-ray energies, and this emission is thought to be associated with the inner disc. Atomic absorption/emission processes in nuclear gas flows are also observed to imprint characteristic features on X-ray spectra. Iron Kα emission lines from 6.40–6.97 keV are formed at least partially by fluorescence in the inner disc, and absorption edges seen mainly below 2 keV reveal major flows of ionized gas in the nucleus. Studies of the complex X-ray spectra of Seyferts and quasars have undergone a revolution wit the launches of Chandra in 1998 and XMM-Newton in 1999. The era of high-resolution X-ray spectroscopy has been initiated by the Chandra and XMM-Newton grating spectrometers. These detectors provide X-ray spectra with 6–100 times higher spectral resolution than those previously available, and they have dramatically enlarged the arsenal of diagnostics available for investigating Seyfert/quasar nuclei. The new generation of X-ray observatories is used to intensively address some of the leading questions about Seyfert/quasar X-ray emission. Some of the most important scientific issues for the next years are: — Matter under strong gravity: Why are relativistically blurred Fe K lines so rare? — What are the extreme X-ray spectral and variability properties of ultrasoft Narrow-Line Seyfert 1 galaxies telling us about Seyferts and quasars more generally? — What is the physical nature of the sharp spectral cut-off in Seyfert galaxies? While the advances expected from the new generation of X-ray observatories are so large and widespread that precise predictions are difficult, it is believed that particularly important progress will be made towards answering these central questions. Below is explained why the questions I have stated are fundamental and timely.

MATTER UNDER STRONG GRAVITY

2007 ◽  
Vol 16 (04) ◽  
pp. 1083-1091
Author(s):  
THOMAS BOLLER
Keyword(s):  
Black Holes ◽  
Accretion Disc ◽  
High Density ◽  
Narrow Line ◽  
X Ray ◽  
Strong Gravity ◽  
Partial Covering ◽  
Density Matter

I report on the discovery of high density matter in the immediate vicinity of the central black holes in the Narrow-Line Seyfert 1 Galaxies 1H 0707-495 and IRAS 13224–3809. The density of these clouds is of the order of 1019 cm -3. The clouds are neutral for Fe and must be embedded into the accretion disc to explain the observations. This results in a partial covering interpretation, where the clouds partially absorb the emission from the accretion disc and part of the emission reaches the observer unabsorbed, leading to a strong soft excess, a sharp Fe K edge without any detectable Fe K reemission. This scenario has been proposed theoretically first by M. Rees in 1987 and appears now to be observationally confirmed with observations of the X-ray observatory XMM-Newton.

scholarly journals Quasi-periodic oscillations around Kerr-MOG black holes

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
Martin Kološ ◽  
Misbah Shahzadi ◽  
Zdeněk Stuchlík
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Frequency ◽  
Stellar Mass ◽  
Tidal Disruption ◽  
Periodic Oscillations ◽  
X Ray ◽  
Strong Gravity ◽  
Modified Theory Of Gravity ◽  
Modified Theory

Abstract The study of the quasi-periodic oscillations (QPOs) of X-ray flux observed in the stellar-mass black hole (BH) binaries can provide a powerful tool for testing the phenomena occurring in strong gravity regime. We thus present and apply to three known microquasars the model of epicyclic oscillations of Keplerian discs orbiting rotating BHs governed by the modified theory of gravity (MOG). We show that the standard geodesic models of QPOs can explain the observationally fixed data from the three microquasars, GRO 1655-40, XTE 1550-564, and GRS 1915+105. We perform a successful fitting of the high frequency (HF) QPOs observed in these microquasars, under assumption of MOG BHs, for epicyclic resonance and its variants, relativistic precession and its variants, tidal disruption, as well as warped disc models and discuss the corresponding constraints of parameters of the model, which are the mass and spin and parameter $$\alpha $$α of the BH.

scholarly journals Suzaku Observations of the Hard X-Ray Variability of MCG −6–30–15: the Effects of Strong Gravity around a Kerr Black Hole

2007 ◽  
Vol 59 (sp1) ◽  
pp. S315-S325 ◽  
Author(s):  
Giovanni Miniutti ◽  
Andrew C. Fabian ◽  
Naohisa Anabuki ◽  
Jamie Crummy ◽  
Yasushi Fukazawa ◽  
...  
Keyword(s):  
Black Hole ◽  
Kerr Black Hole ◽  
X Ray ◽  
Strong Gravity
Sign in / Sign up

Export Citation Format

Share Document