We determined the basic parameters, such as the central black hole mass (M), the boosting factor (or Doppler factor) (δ), the propagation angle (Φ) and the distance along the axis to the site of γ-ray production (d) for 23 γ-ray-loud blazars using their available variability timescales. In this method, the absorption effect depends on the γ-ray energy, emission size and property of the accretio...

We critically assess the role of the Blandford-Znajek mechanism in the powering of outflows from accretion disk-fed black holes. We argue that there is no reason to suppose that the magnetic field threading the central spinning black hole differs significantly in strength from that threading the central regions of the disk. In this case, we show that the electromagnetic output from the inner di...

If supermassive black holes in centres of galaxies form by merging of black-hole remnants of massive Population III stars, then there should be a few black holes of mass one or two orders of magnitude smaller than that of the central ones, orbiting around the centre of a typical galaxy. These black holes constitute a weak perturbation in the gravitational potential, which can generate wave phen...

We describe a one-parameter family of models of stable spherical stellar systems in which the phase-space distribution function depends only on energy. The models have similar density pro les in their outer parts ( / r 4 ) and central power-law density cusps, / r 3 , 0 < 3. The family contains the Ja e (1983) and Hernquist (1990) models as special cases. We evaluate the surface brightness pro l...

in this study, the daily total ozone column (toc) measured by the instruments of toms (2001) and omi (2005-2011) satellites and brewer ground station (2002-2004) is used to investigate the extreme ozone mini-holes over esfahan. based on previous reports on validation of the toc data products, it is found that there is no problem with homogenization of data records, which was provided by the abo...

The central bulge of M31 is observed to have two distinct brightness peaks with the separation of ∼ 2 pc. Tremaine (1995) recently proposed a new idea that the M31’s nucleus is actually a single thick eccentric disk surrounding the central super-massive black hole. In order to explore the origin of the proposed eccentric disk, we numerically investigate the dynamical evolution of a merger betwe...

In the present work, the edge stretchability of advanced high strength steel (AHSS) was investigated experimentally and numerically using both a hole expansion test and a tensile specimen with a central hole. The experimental fracture strains obtained using the hole expansion and hole tension test in both reamed and sheared edge conditions were in very good agreement, suggesting the tests are e...

We explore the relation between the linear length of radio core and the central black hole mass for a sample of radio-loud active galactic nuclei (AGNs). An empirical relation between the size of the broad line region (BLR) and optical luminosity is used to estimate the size of the BLR. The black hole mass is derived from Hβ line width and the radius of the BLR on the assumption that the clouds...