Related papers: Space density of optically-selected type 2 quasars

Recent works have suggested that selection criteria based on MIR colors can be used to reveal a population of dust-enshrouded, extremely luminous quasars at z>1. However the X-ray spectral properties of these intriguing sources still remain…

We present Hubble Space Telescope images, and spectral energy distributions from optical to infrared wavelengths for a sample of six 0.3<z<0.8 type-2 quasars selected in the mid-infrared using data from the Spitzer Space Telescope. All the…

We present the result of our low-luminosity quasar survey in the redshift range of 4.5 < z < 5.5 in the COSMOS field. Using the COSMOS photometric catalog, we selected 15 quasar candidates with 22 < i' < 24 at z~5, that are ~ 3 mag fainter…

Using the 2MASS Second Incremental Data Release, we have searched for near infrared counterparts to 13214 quasars from the Veron-Cetty & Veron(2000) catalog. We have detected counterparts within 4 arcsec for 2277 of the approximately 6320…

We present the discovery of three new quasars at z>6 in 1300 deg^2 of SDSS imaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3 (z=6.23) and J163033.90+401209.6 (z=6.05). The first two objects have weak Ly alpha emission lines;…

The spectral energy distributions and infrared (IR) spectra of a sample of obscured AGNs selected in the mid-IR are modeled with recent clumpy torus models to investigate the nature of the sources, the properties of the obscuring matter,…

We present a measurement of the Type I quasar luminosity function at z=5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M_1450<-26) with Sloan Digital Sky Survey…

A population of quasars at z ~ 2 is determined based on dust luminosities vLv(7.8 um) that includes unobscured, partially obscured, and obscured quasars. Quasars are classified by the ratio vLv(0.25 um)/vLv(7.8 um) = UV/IR, assumed to…

We present optical spectroscopy of a sample of 77 luminous AGN and quasars selected on the basis of their mid-infrared colors. Our objects are selected from the Spitzer Extragalactic First Look Survey and SWIRE XMM-LSS fields, with a…

This paper presents the first results of a survey for bright quasars (V < 14.5 and R<15.4) covering the North Hemisphere at galactic latitudes |b|>30. The photometric database is derived from the GSC and USNO catalogs. Quasars are…

We have conducted a pilot survey for z>3.5 quasars by combining the FIRST radio survey with the SDSS. While SDSS already targets FIRST sources for spectroscopy as quasar candidates, our survey includes fainter quasars and greatly improves…

We have conducted spectropolarimetry of 12 type II (obscured) quasar candidates selected from the spectroscopic database of the Sloan Digital Sky Survey based on their emission line properties. Polarization was detected in all objects, with…

Utilizing 21 new Chandra observations as well as archival Chandra, ROSAT, and XMM-Newton data, we study the X-ray properties of a representative sample of 59 of the most optically luminous quasars in the Universe (M_i~~-29.3 to -30.2)…

This is the fourth paper in a series aimed at finding high-redshift quasars from five-color imaging data taken along the Celestial Equator by the SDSS. during its commissioning phase. In this paper, we use the color-selected sample of 39…

We use the ROSAT All Sky Survey (RASS) to study the soft X-ray properties of a homogeneous sample of 46,420 quasars selected from the third data release of the Sloan Digital Sky Survey (SDSS). Optical luminosities, both at rest-frame…

Luminous type-2 quasars in which the glow from the central black hole is obscured by dust are ideal targets for studying their host galaxies and the quasars' effect on galaxy evolution. Such feedback appears ubiquitous in luminous obscured…

We present the first sample of spectroscopically confirmed heavily reddened broad-line quasars selected using the new near infra-red VISTA Hemisphere Survey and WISE All-Sky Survey. Observations of four candidates with (J-K)>2.5 and K<=16.5…

We present a new sample of purely near infra-red selected KVega<16.5 extremely red ((J-K)>2.5) quasar candidates at z~2 from 900 sq deg of data in the UKIDSS Large Area Survey (LAS). Five of these are spectroscopically confirmed to be…

In a popular scenario for the coevolution of massive black holes and galaxies, major mergers of gas-rich galaxies fuel vigorous star formation and obscured (type 2) quasar activity until energy feedback from the active galactic nucleus…

Using self-consistent, physically motivated models, we investigate the X-ray obscuration in 19 Type 2 [OIII] 5007 \AA\ selected AGN, 9 of which are local Seyfert 2 galaxies and 10 of which are Type 2 quasar candidates. We derive reliable…