New virial black-hole mass estimates are presented for a sample of 72 AGN covering three decades in optical luminosity. Using a model in which the AGN broad-line region (BLR) has a flattened geometry, we investigate the M bh − L bulge relation for a combined 90-object sample, consisting of the AGN plus a sample of 18 nearby inactive elliptical galaxies with dynamical black-hole mass measurement...

Globular clusters are both primary fossils of galactic evolution and formation ideal laboratories for constraining the low-mass metal-poor stars. RR Lyrae type II Cepheid variables low-mass, radially pulsating stars that trace old-age stellar populations. These standard candles in globular crucial measuring their precise distances and, turn, absolute ages, calibration extragalactic distance sca...

The physical processes that define the spine of the galaxy cluster X-ray luminosity–temperature (L–T) relation are investigated using a large hydrodynamical simulation of the universe. This simulation models the same volume and phases as the millennium simulation and has a linear extent of 500 h Mpc. We demonstrate that mergers typically boost a cluster along but also slightly below the L–T rel...

ABSTRACT Galaxy clusters show a variety of intracluster medium properties at fixed mass in gas fractions, X-ray luminosity and surface brightness. In this work, we investigate whether the yet-undetermined cause that produces low brightness also affects galaxy properties, such as richness, richness concentration, width location red sequence, colour, luminosity, dominance brightest cluster galaxy...

There has been extensive recent progress in X-ray observations of clusters of galaxies with the analysis of the entire ASCA database and recent new results from Beppo-SAX, Chandra, and XMM-Newton. The temperature profiles of most clusters are isothermal from 0.05– 0.6 Rviral, contrary to theoretical expectations and early results from ASCA. Similarly, the abundance profiles of Fe are roughly co...

The dynamical mass of clusters of galaxies, calculated in terms of modified Newtonian dynamics, is a factor of two or three times smaller than the Newtonian dynamical mass but remains significantly larger than the observed baryonic mass in the form of hot gas and stars in galaxies. Here I consider further the suggestion that the undetected matter might be in the form of cosmological neutrinos w...

We show that Massive Black Holes of AGNs follow the same approximately linear relation with the luminosity of the host spheroid (bulge) found in normal (quiescent) galaxies, with the black hole mass being 0.002 that of the bulge. We also demonstrate that Narrow line AGNs seem to have a significantly lower Mbh/Lbulge ratio, which implies a new strong correlation between Mbh/Lbulge and the width ...

We observed brown dwarfs in different evolutionary stages with the Chandra X-ray Observatory with the aim to disentangle the influence of different stellar parameters on the X-ray emission of substellar objects. The ages of our three targets (HR 7329 B, Gl 569 Bab, and HD 130948 BC) are constrained by them being companions to main-sequence stars of known age. With both known age and effective t...

The period-luminosity relation of Miras and semiregular variables in the Large Magellanic Cloud and in the Galaxy is used to locate their instability domain in the Hertzsprung-Russell diagram. We take advantage of the considerable width in luminosity of the relation at given period to assign masses to the observed long-period variables using stellar models on the the asymptotic giant branch and...

The period-luminosity relation of Miras and semiregular variables in the Large Magellanic Cloud and in the Galaxy are used to locate their instability domain in the Hertzsprung-Russell diagram. We take advantage of the considerable width in luminosity of the relation at given period to assign masses to the observed long-period variables using stellar models on the the asymptotic giant branch an...