We present the Period{Luminosity relation from 290 Cepheids toward the LMC and 597 Cepheids towards the SMC respectively obtained from the monitoring of 1.134.000 and 504.000 stars over 150 nights using the two 4k 8k CCD camera of the Eros2 microlensing project. A slope break of the Period{Luminosity relation has been observed for SMC fundamental mode Cepheids with periods smaller than 2 days. ...

We investigate the accretion onto luminous bodies with hard surfaces within the framework of newtonian theory. The accreting gases are assumed to be polytropes and their selfgravitation is included. A remarkable feature of the model is that under proper boundary conditions some parameters of the sonic point are the same as in the Bondi model and the relation between luminosity and the gas abund...

We derive constraints on the mass-temperature relation of galaxy clusters from their observed luminosity-temperature relation and X-ray temperature function. Adopting the isothermal gas in hydrostatic equilibrium embedded in the universal density profile of dark matter halos, we compute the X-ray luminosity for clusters as a function of their hosting halo mass. We find that in order to reproduc...

Non-parametric, empirically based, models for associating galaxy luminosities with halo/subhalo masses are being developed by several groups and we present here an updated version of the Vale & Ostriker (2004) version of this model. This is based on a more accurate, self-consistent treatment of subhalo mass loss and revised results for the subhalo mass function to address this question anew. We...

Metal-poor globular clusters (GCs) are our local link to the earliest epochs of star formation and galaxy building. Studies of extragalactic GC systems using deep, high-quality imaging have revealed a small but significant slope to the color-magnitude relation for metal-poor GCs in a number of galaxies. We present a study of the M87 GC system using deep, archival HST/ACS imaging with the F606W ...

We derive the kinetic luminosity function for flat-spectrum radio jets, using the empirical and theoretical scaling relation between jet power and radio core luminosity. The normalization for this relation is derived from a sample of flat-spectrum cores in galaxy clusters with jet-driven X-ray cavities. The total integrated jet power at z p 0 is . By integrating over redshift, we determine the ...

Based on CHANDRA observations of nearby starburst galaxies and RXTE/ASM, ASCA and MIR-KVANT/TTM studies of high mass X-ray binary (HMXB) populations in the Milky Way and Magellanic Clouds, we propose that the number and/or the collective X-ray luminosity of HMXBs can be used to measure the star formation rate (SFR) of a galaxy. We show that, within the accuracy of the presently available data, ...

We present a Bayesian inference analysis of the Markevitch (1998) and Allen & Fabian (1998) cooling flow corrected X-ray cluster temperature catalogs that constrains the slope and the evolution of the empirical X-ray cluster luminosity-temperature (L-T ) relation. We find that for the luminosity range 1044.5 erg s−1 ∼< Lbol ∼< 10 46.5 erg s−1 and the redshift range z ∼< 0.5, Lbol ∝ T 2.80 −0.15...

In a recent paper, we calculate spectral energy distributions (SEDs) for 1425 Fermi blazars, classifications of low synchrotron peak sources (LSPs) if log νp(Hz) ≤ 14.0, intermediate synchrotron peak sources (ISPs) if 14.0 < log νp(Hz) ≤ 15.3, and high synchrotron peak sources (HSPs) if log νp(Hz) > 15.3 are made based on 999 logarithms of synchrotron peak frequencies with known redshift, and w...

We use the Hubble Ultra Deep Field (UDF) to study the galaxy luminosity-size (M-R e) distribution. With a careful analysis of selection effects due to both detection completeness and measurement reliability we identify bias-free regions in the M-R e plane for a series of volume-limited samples. We also investigate the colour-log(n) distribution of these galaxies and further subdivide our data b...