相关论文: Black Hole Blackbodies
We have studied the host galaxies of a sample of radio-loud AGN spanning more than four decades in the energy output of the nucleus. The core sample includes 40 low-power sources (BL Lac objects) and 22 high-power sources (radio-loud…
The coupling of a string to gravity allows for Schwarzschild black holes whose entropy to area relation is $S=(A/4)(1-4\mu)$, where $\mu$ is the string tension. This departure from the A/4 universality results from a string instanton…
We report the results of Chandra and XMM-Newton observations of an ultra-luminous supersoft X-ray source in M101. M101 ULX-1 underwent 2 outbursts in 2004 during which the peak bolometric luminosities reached 1e41 erg/s. The outburst…
A standard disk around an accreting black hole may become effectively optically-thin and scattering dominated in the inner region, for high accretion rates (as already predicted by the Shakura-Sunyaev model). Radiative emission from that…
Eddington outflows probably regulate the growth of supermassive black holes (SMBH) in AGN. I show that effect of the Rayleigh--Taylor instability on these outflows means that SMBH masses are likely to be a factor of a few below the $M -…
A recent paper (arXiv:0804.3463) claims that the presence of a soft X-ray component in an X-ray source in NGC 6946 provides strong evidence that its black hole mass is definitely $>100\msun$, and more probably $\sim 400\msun$, even if the…
Observed spectra of Active Galactic Nuclei (AGN) and luminous X-ray binaries in our Galaxy suggest that both hot (~10^9 K) and cold (~10^6 K) plasma components exist close to the central accreting black hole. Hard X-ray component of the…
We present the results of X-ray variability and spectral analysis of a sample of 15 new candidates for active galactic nuclei with relatively low-mass black holes (BHs). They are selected from the Second XMM-Newton Serendipitous Source…
As a charged black hole reaches its extremal state via Hawking radiation, quantum effects become important for its thermodynamic properties when its temperature is below a mass gap scale. Using AdS$_2$/CFT$_1$ correspondence and solutions…
We present a pilot study of the X-ray properties of intermediate-mass (~10^5-10^6 M_sun) black holes in active galaxies using the Chandra X-ray telescope. Eight of the 10 active galaxies are detected with a significance of at least 3 sigma,…
In this work, we derive rigorous and universal bounds on the geometric characteristics of black holes in asymptotically flat spacetimes under assumptions that weak energy condition is satisfied. We prove that the event horizon radius, the…
A distinct visual signature occurs in black holes that are surrounded by optically thin and geometrically thick emission regions. This signature is a sharp-edged dip in brightness that is coincident with the black-hole shadow, which is the…
We study the relation between obscuration and supermassive black hole (SMBH) growth using a large sample of hard X-ray selected Active Galactic Nuclei (AGN). We find a strong decrease in the fraction of obscured sources above the Eddington…
There are reasons (which we enumerate) to think that an infinite extra dimension will harbor a black hole. In this case, brane-localized modes of gravity and gauge fields become quasilocalized, and light from a distant object can become…
We examine radiative standing shocks in advective accretion flows around stellar-mass black holes by 2D radiation hydrodynamic simulations, focusing on the super-Eddington accreting flow. Under a set of input flow parameters responsible for…
It is sometimes suggested that phenomenological power-law plus cool disc-blackbody models represent the simplest, most robust interpretation of the X-ray spectra of bright ultraluminous X-ray sources (ULXs); this has been taken as evidence…
We calculate the particle spectra of evaporating self-dual black holes that are potential dark matter candidates. We first estimate the relevant mass and temperature range and find that the masses are below the Planck mass, and the…
About eight minutes before a black hole expires it has a decreasing mass of 10^{10} g, an increasing temperature of 1 TeV, and an increasing luminosity of 7x10^{27} erg/s. I show that such a black hole is surrounded by a quasi-stationary…
The ultraluminous X-ray sources (ULXs) were isolated in external galaxies for the last 5 years. Their X-ray luminosities exceed 100-10000 times those of brightest Milky Way black hole binaries and they are extremely variable. There are two…
If the early optical data of GRB 060218 up to 1e5 s are interpreted as the black-body flux associated with the supernova shock breakout, we can derive lower limits to the bolometric luminosity and energetics of this black-body component.…