相关论文: The basic parameters of gamma-ray-loud blazars
The masses of central supermassive black holes in a soft X-ray selected sample of the narrow-line Seyfert 1 galaxies (NLS1s) are estimated by some different methods to test their theoretical models. Apart from the methods using the H$\beta$…
We construct a model for the formation of black holes within galactic bulges. The initial state is a slowly rotating isothermal sphere, characterized by effective transport speed $\aeff$ and rotation rate $\Omega$. The black hole mass is…
The standard blazar paradigm consists of a supermassive black hole that expels relativistic jets of magnetized plasma in our direction. This plasma entrains nonthermal synchrotron-emitting electrons that furthermore scatter…
M82 X-1, the brightest X-ray source in the galaxy M82, has been thought to be an intermediate-mass black hole (100 to 10,000 solar masses) because of its extremely high luminosity and variability characteristics, although some models…
We propose a way to constrain the primordial black hole (PBH) abundance in the range of PBH masses $m$ around $10^{20}$g based on their capture by Sun-like stars in dwarf galaxies, with subsequent star destruction. We calculate numerically…
The collapse of baryons into extremely massive stars with masses exceeding 10^4 M_Sun in a small fraction of protogalaxies at z > 10 is a promising candidate for the origin of supermassive black holes, some of which grow to a billion solar…
There exists a well known relation between the mass of the supermassive black hole (SMBH) in the center of galaxies and their bulge mass or central velocity dispersion. This suggests a co-evolution between SMBH and their galaxy hosts. Our…
Primordial black holes (PBHs) with a mass from $10^{-16}$ to $10^{-11}\,M_\odot$ may comprise 100% of dark matter. Due to a combination of wave and finite source size effects, the traditional microlensing of stars does not probe this mass…
We estimate the mass of the central black hole in our Galaxy from stellar kinematical data published by Ghez et al. (1998) and Genzel et al. (2000). For this we develop a method, related to Merritt (1993), for non-parametrically…
A measurement of the expansion rate of the Universe (that is the Hubble constant, H0) is derived here using the gamma-ray attenuation observed in the spectra of gamma-ray sources produced by the interaction of extragalactic gamma-ray…
Primordial black holes (PBHs), originating from the gravitational collapse of large overdensities in the early Universe, emerge as a compelling dark matter (DM) candidate across a broad mass range. Of particular interest are ultra-light…
The mass function of super-massive black holes in our cosmic neighborhood is required to understand the statistics of their activity and consequently the origin of the ultra high energy particles. We determine a mass function of black hole…
We used the widths of H$\beta$ and [OIII] emission lines to investigate the black hole--bulge relation in radio-loud AGNs, radio-quiet AGNs and NLS1s. The central black hole mass, $M_{bh}$, is estimated from the H$\beta$ line width and the…
The Eddington ratio ($\lambda_{\rm Edd}$) of supermassive black holes (SMBHs) is a fundamental parameter that governs the cosmic growth of SMBHs. Although gas mass accretion onto SMBHs is sustained when they are surrounded by large amounts…
We present the first results from our on-going program to estimate black hole masses [M(BH)] of nearby BL Lac objects. The estimates are based on stellar velocity dispersion (sigma) of the BL Lac host galaxies from optical spectroscopy, and…
We propose a new method of estimation of the black hole masses in AGN based on the normalized excess variance, sigma_{nxs}^2. We derive a relation between sigma_{nxs}^2, the length of the observation, T, the light curve bin size, Delta t,…
Within the mass range of $10^{16}-5\times 10^{18}$ g, primordial black holes (PBHs) persist as plausible candidates for dark matter. Our study involves a reassessment of the constraints on PBHs through a comparative analysis of the cosmic…
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,…
[Abridged] To investigate the evolution in the relation between galaxy stellar and central black hole mass we construct a volume limited complete sample of 85 AGN with host galaxy stellar masses M_{*} > 10^{10.5} M_{sol}, and specific X-ray…
Advances in high angular resolution astronomy make it conceivable that black hole dark matter could be detected via angular deviation effects. Assuming the dark matter in the galaxy is made of solar mass black holes, there is a non-trivial…