Related papers: A Candidate Dual QSO at Cosmic Noon
We describe a method to measure the M-sigma relation in the non-local universe using dust-obscured QSOs. We present results from a pilot sample of nine 2MASS red QSOs with redshifts 0.14<z<0.37. We find that there is an offset (0.8 dex, on…
The results of deep-imaging observations of a candidate of an absorbed QSO at z=0.653, AX J131831+3341, are presented. AX J131831+3341 was found during the course of optical follow-up observations of the ASCA Large Sky Survey, and has an…
We analyze 23 spectroscopically confirmed Type-2 quasars (QSOs) selected from the WISE 22$\rm \mu$m band in the SDSS Stripe 82 region, focusing on their multi-band photometry and spectral energy distributions (SEDs). These objects were…
Two new samples of QSOs have been constructed from recent surveys to test the hypothesis that the redshift distribution of bright QSOs is periodic in $\log(1+z)$. The first of these comprises 57 different redshifts among all known close…
We present the first results from the Distant Radio Galaxies Optically Non-detected in the SDSS (DRaGONS) Survey. Using a novel selection technique for identifying high redshift radio galaxy (HzRG) candidates, a large sample of bright…
We report on our search for distant clusters of galaxies based on optical and X-ray follow up observations of X-ray candidates from the SHARC survey. Based on the assumption that the absence of bright optical or radio counterparts to…
A picture has emerged connecting QSOs with Sub-Millimetre Galaxies (SMGs) through an evolutionary sequence in which forming galaxies are initially FIR-luminous but X-ray weak, similar to known SMGs. As the black hole and spheroid grow with…
Observed high-redshift QSOs, at z~6, may reside in massive dark matter (DM) halos of more than 10^{12} Msun and are thus expected to be surrounded by overdense regions. In a series of 10 constrained simulations, we have tested the…
We investigated the properties of a sample of red Quasi-stellar Objects (QSOs) using optical, radio, and infrared data. These QSOs were selected from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) quasar catalog. We only selected…
Quasars (QSOs) hosting supermassive black holes are believed to reside in massive halos harboring galaxy overdensities. However, many observations revealed average or low galaxy densities around $z\gtrsim6$ QSOs. This could be partly…
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…
First indications of the warm/hot intergalactic medium, tracing out the large scale structure of the universe, have been obtained in sensitive Chandra and XMM-Newton high resolution absorption line spectroscopy of bright blazars. High…
During galaxy merger events, the supermassive black holes in the center of the galaxies may form a pair of active galactic nuclei (AGN) with kpc-scale or even pc-scale separation. Recently, optical observations revealed a promising dual AGN…
Quasars (QSOs) are extremely luminous active galatic nuclei currently observed up to redshift $z=7.642$. As such, they have the potential to be the next rung of the cosmic distance ladder beyond SNe Ia, if they can reliably be used as…
We describe a possible new class of X-ray sources that have robust detections in ultra-deep Chandra data, yet have no detections at all in our deep multi-band GOODS Hubble Space Telescope (HST) ACS images, which represent the highest…
We present multicolour images of the hosts of three z=2 QSOs previously detected in R-band by our group. The luminosities, colours and sizes of the hosts overlap with those of actively star-forming galaxies in the nearby Universe. Radial…
We report the possible discovery of multiple gravitationally-lensed images of QSOs with angular separations on arcminute scales. The QSOs were selected from the completed 2dF QSO survey as having redshifts and optical colours which are…
We present Chandra and Spitzer data of the 186, extragalactic, hard 2-10 keV X-ray selected sources, which lie in the central part of the Chandra Deep Field South (CDFS). For the vast majority of sources (99.5%) there is a spectroscopic or…
Together with the CMB, the three sources of information that astronomers have at high redshift as probes of the formation and evolution of the LSS are QSOs, galaxies and absorbers observed in the spectrum of distant background objects. In…
We combine results from deep ALMA observations of massive ($M_*>10^{10}\;M_{\odot}$) galaxies at different redshifts to show that the column density of their inter stellar medium (ISM) rapidly increases towards early cosmic epochs. Our…