Related papers: The luminous host galaxies of high redshift BL Lac…
In the present-day universe, supermassive black hole masses (MBH) appear to be strongly correlated with their galaxy's bulge luminosity, among other properties. In this study, we explore the analogous relationship between MBH, derived using…
We have compiled a sample of $\sim 9600$ bright, $i\le 18.95$, red, $b_j-r>2$, candidate galaxies in an area of 220 deg$^2$. These are luminous, $L > L^*$, field early-type galaxies with redshifts $0.3 \la z \la 0.6$. We present a redshift…
The BL Lac object 3C66A is one of the most luminous extragalactic sources at TeV $\gamma$-rays (VHE, i.e. $E >100$ GeV). Since TeV $\gamma$-ray radiation is absorbed by the extragalactic background light (EBL), it is crucial to know the…
We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies ($\log_{10}[M_{h}^*/M\odot]>10.5$) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift,…
We construct a sample of 3,516 radio-loud host galaxies of active galactic nuclei (AGN) from the optical Sloan Digital Sky Survey (SDSS) and Faint Images of the Radio Sky at Twenty cm (FIRST). These have 1.4 GHz luminosities in the range…
We present results of a deep HST/WFPC2 imaging study of 17 quasars at z~0.4, designed to determine the properties of their host galaxies. The sample consists of quasars with absolute magnitudes in the range -24>M_V>-28, allowing us to…
In this paper we re-visit the observational relation between X-ray luminosity and temperature for high-z galaxy clusters and compare it with the local L_X-T and with theoretical models. To these ends we use a sample of 17 clusters extracted…
We present rest-frame UV \textit{Hubble Space Telescope} imaging of the largest and most complete sample of 23 long duration gamma-ray burst (GRB) host galaxies between redshifts 4 and 6. Of these 23, we present new WFC3/F110W imaging for…
We have been conducting an imaging survey to detect host galaxies of radio-quiet QSOs at high redshift (z = 2), in order to compare them with those of radio-loud objects. Six QSOs were observed in the R passband with the auxiliary port of…
It has been suggested recently that the rate of gamma-ray bursts (GRBs) is proportional to the star formation rate in the universe. In this paper, we study the nature of GRB hosts expected in this scenario. We improve upon previous studies…
Our understanding of the nature of DLA systems at large redshifts, ostensibly progenitors of normal disk galaxies, depends critically on their direct identifications with galaxies, and the resulting measurements of their properties. A few…
The galactic environment of Gamma Ray Bursts can provide good evidence about the nature of the progenitor system, with two old arguments implying that the burst host galaxies are significantly subluminous. New data and new analysis have now…
We present the Super Eight galaxies - a set of very luminous, high-redshift ($7.1<z<8.0$) galaxy candidates found in Brightest of Reionizing Galaxies (BoRG) Survey fields. The original sample includes eight galaxies that are $Y$-band…
We have obtained the first constraints on extended Ly-alpha emission at z ~ 1 in a sample of five radio galaxies. We detect Ly-alpha emission from four of the five galaxies. The Ly-alpha luminosities range from 0.1 - 4 times 10^43 erg/s and…
Using three complete, radio flux limited, blazar samples we compare the LogN-LogS and the preliminary radio luminosity function of the general population of BL Lacs to those of the subclass of high energy synchrotron peaked (HBL) BL Lacs.…
We present optical spectroscopy and deep optical/near-IR photometry of 4 luminous metal-poor blue compact galaxies (BCGs) and two of their companions. With the aid of spectral evolutionary models (SEMs) and structural parameters derived…
We report redshift measurements for 12 BL Lacertae objects from a program aimed at obtaining high signal to noise (up to ~ 500) optical spectroscopy of a mixed sample of objects. The new observations, gathered with the 8 m ESO Very Large…
We present K-band imaging and photometry of a sample of 52 radio loud quasars (RQs) selected from the B3 survey with flux densities above 0.5 Jy at 408 MHz. The optical completeness of the sample is 90% and the quasars cover the redshift…
We study properties of the host galaxies of 15 hard X-ray selected type-2 active galactic nuclei (AGNs) at intermediate redshifts (0.05$<z<$0.6) detected in $ASCA$ surveys. The absorption corrected hard X-ray luminosities $L_{\rm 2-10 keV}$…
High redshift radio galaxies are among the largest, most luminous, most massive, and most beautiful objects in the Universe. They are generally identified from their radio emission, thought to be powered by accretion of matter onto…