相关论文: Iron Line Profiles in Strong Gravity
Recently, a rotating black hole solution was found in Vector-Tensor Galileons modified gravity that has some significant differences from the Kerr black hole solution. We study the iron line shape that is part of the reflection spectrum of…
We present preliminary results on the properties of relativistically broadened Fe K-alpha lines in a collection of more then 100 Active Galactic Nuclei (AGN) observed by the XMM-Newton EPIC-pn camera. Our main conclusions can be summarized…
We present a novel way to investigate scalar field profiles around black holes with an accretion disc for a range of models where the Compton wavelength of the scalar is large compared to other length scales. By analysing the problem in…
The relativistically-broadened reflection spectrum, observed in both AGN and X-ray binaries, has proven to be a powerful probe of the properties of black holes and the environments in which they reside. Being emitted from the inner-most…
We present a full set of model atmosphere equations for the accretion disk around a supermassive black hole irradiated by hard X-ray lamp of power-law spectral distribution. Model equations allow for multiple Compton scattering of radiation…
The Fe K_\alpha fluorescent line at 6.4 keV is a powerful probe of the space-time metric in the vicinity of accreting compact objects. We investigated here how some alternative theories of gravity, namely Scalar tensor Theories, that invoke…
Relativistic spectral lines from the accretion disc of a neutron star low-mass X-ray binary can be modelled to infer the disc inner edge radius. A small value of this radius tentatively implies that the disc terminates either at the neutron…
Recent observational data from the Event Horizon Telescope (EHT) collaboration provide convincing realistic evidence for the existence of black hole rotation. From a phenomenological perspective, a recently proposed stable rotating regular…
We generalize our previous work on gravitational lensing by a Kerr black hole in the strong deflection limit, removing the restriction to observers on the equatorial plane. Starting from the Schwarzschild solution and adding corrections up…
Black hole based tests of general relativity have proliferated in recent times with new and improved detectors and telescopes. Modelling of the black hole neighborhood, where most of the radiation carrying strong-field signature originates,…
General relativity's prediction that all black holes are described by the Kerr metric, irrespective of their size, can now be empirically tested using electromagnetic observations of supermassive black holes and gravitational waves from…
The reflection spectrum produced by a cold medium illuminated by X-ray photons is not isotropic and its shape depends on the emission angle. In the reflection spectrum of an accretion disk of a black hole, the value of the emission angle…
We describe the methodology and compute the illumination of geometrically thin accretion disks around black holes of arbitrary spin parameter $a$ exposed to the radiation of a point-like, isotropic source at arbitrary height above the disk…
Recent quasar microlensing observations have constrained the sizes of X-ray emission regions to be within about 10 gravitational radii of the central supermassive black hole. Therefore, the X-ray emission from lensed quasars is first…
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…
I report the discovery of a prominent broad and asymmetrical feature near 6.4 keV in the Seyfert 1 MCG-02-14-009 (z=0.028) with XMM-Newton/EPIC. The present short X-ray observation (PN net exposure time ~5 ks) is the first one above 2 keV…
The Kerr metric is one of the most important solutions to Einstein's field equations, describing the gravitational field outside a rotating black hole. We thoroughly analyze the curvature scalar invariants to study the Kerr spacetime by…
We present evidence for widespread relativistic effects in the central regions of active galactic nuclei. In a sample of 18 Seyfert 1 galaxies observed by \asca, 14 show an iron K$\alpha$ line which is is resolved, with mean width…
Relativistic reflection features in the X-ray spectra of black hole binaries and AGNs are thought to be produced through illumination of a cold accretion disk by a hot corona. In this work, we assume that the corona has the shape of an…
We study optical effects in quintessential Kerr black hole spacetimes corresponding to the limiting case of the equation-of-state parameter $\omega_{q}=-1/3$ of the quintessence. In dependence on the dimensionless quintessential field…