Related papers: Extremely Red Objects: an X-ray dichotomy

We present near-IR spectroscopy and HST imaging of EROJ164023, an Extremely Red Object (ERO) with R-K=5.9 at z=1.05. EROJ164023 is a disk galaxy, with an optical/IR spectral energy distribution which is strongly reddened by dust…

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…

Deep near-infrared and optical imaging surveys in the field reveal a curious population of galaxies that are infrared-bright (I-K>4), yet with relatively blue optical colors (V-I<2). Their surface density, several per square arcminute at…

We present the results of a K-band imaging survey of 40 arcmin^{2} in fields around 14 radio-loud AGN (6 radio galaxies and 8 quasars) with z>1.5. The survey, 80% complete to K<19.2 and complemented by R-band imaging, aimed at investigating…

We investigate the nature of extremely red galaxies (ERGs), objects whose colours are redder than those found in the red sequence present in colour-magnitude diagrams of galaxies. We selected from the Sloan Digital Sky Survey Data Release 7…

We define a sample of 27 radio-excess AGN in the Chandra Deep Field North by selecting galaxies that do not obey the radio/infrared correlation for radio-quiet AGN and star-forming galaxies. Approximately 60% of these radio-excess AGN are…

Very deep near-infrared observations have recently uncovered a significant population of red galaxies at redshifts z>2. These distant red galaxies (DRGs) are efficiently selected by the criterion J-K>2.3. We use Chandra data to examine the…

We present results on a search of heavily obscured active galaxies z>1.7 using the rest-frame 9-20 keV excess for X-ray sources detected in the deep XMM-CDFS survey. Out of 176 sources selected with the conservative detection criteria (>8…

Deep Chandra X-ray exposures provide an efficient route for locating optically faint active galactic nuclei (AGN) at high redshifts. We use deep multicolor optical data to search for z>5 AGN in the 2 Ms X-ray exposure of the Chandra Deep…

Deep VLT optical spectroscopy, HST+ACS (GOODS) imaging and VLA observations are used to unveil the nature of a complete sample of 47 EROs with R-Ks>5 and Ks<20. The spectroscopic redshift completeness is 62%. Morphological classification…

We study the properties of a sample of 211 heavily-obscured Active Galactic Nucleus (AGN) candidates in the Extended Chandra Deep Field-South selecting objects with f_24/f_R>1000 and R-K>4.5. Of these, 18 were detected in X-rays and found…

The paper presents the identification of the stars in the lower part of the Main Sequence among the objects of the deep survey of the equatorial region of the sky, performed by the eROSITA telescope at the SRG orbital observatory. Of the…

We present followup optical g', r', and i', imaging and spectroscopy of serendipitous X-ray sources detected in 6 archival Chandra, images included in the Chandra, Multiwavelength Project (ChaMP). Of the 486 X-ray sources detected between…

This is the first paper in a series presenting and analyzing data for a K-selected sample of galaxies collected in order to identify and study galaxies at moderate to high redshift in rest-wavelength optical light. The sample contains 842…

We have obtained spectroscopic redshifts for 24 red galaxies from a sample with median Ks=18.7 and F814W - Ks > 4, using the Keck telescope. These EROshave high resolution morphologies from HST (Yan & Thompson 2003). Among the 24 redshifts,…

In order to trace the instantaneous star formation rate at high redshift, and hence help understanding the relation between the different emission mechanisms related to star formation, we combine the recent 4 Ms Chandra X-ray data and the…

Quasars may have played a key role in limiting the stellar mass of massive galaxies. Identifying those quasars in the process of removing star formation fuel from their hosts is an exciting ongoing challenge in extragalactic astronomy. In…

We present the X-ray spectra of 86 optically-identified sources in the 13H XMM-Newton/Chandra deep field which have >70 X-ray counts. The sample consists of 50 broad line AGN, 25 narrow emission line galaxies, 6 absorption line galaxies,…

We are carrying out sensitive X-ray observations with Chandra and XMM of type II quasars selected from the Sloan Digital Sky Survey based on their optical emission line properties. We present observations of four objects at redshifts 0.4 <…

The sources discovered in deep hard X-ray surveys with 2-8 keV fluxes of 10^-14 erg cm^-2 s^-1 make up the bulk of the X-ray background at these energies. We present here detailed multi-wavelength observations of three such sources from the…