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Table · dataset · 2015

UKIDSS+FIRST+SDSS red QSOs candidates

Listed in IVOA Registry (Virtual Observatory)

We present the results of a pilot survey to find dust-reddened quasars by matching the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio catalog to the UKIDSS near-infrared survey and using optical data from Sloan Digital Sky Survey to select objects with very red colors.

Description

The deep K-band limit provided by UKIDSS allows for finding more heavily reddened quasars at higher redshifts as compared with previous work using FIRST and Two Micron All Sky Survey (2MASS).

We selected 87 candidates with K<=17.0 from the UKIDSS Large Area Survey (LAS) First Data Release (DR1), which covers 190deg^2^. These candidates reach up to ~1.5mag below the 2MASS limit and obey the color criteria developed to identify dust-reddened quasars. We have obtained 61 spectroscopic observations in the optical and/or near-infrared, as well as classifications in the literature, and have identified 14 reddened quasars with E(B-V)>0.1, including 3 at z>2.

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We study the infrared properties of the sample using photometry from the Wide-Field Infrared Survey Explorer and find that infrared colors improve the efficiency of red quasar selection, removing many contaminants in an infrared-to-optical color-selected sample alone. The highest-redshift quasars (z>~2) are only moderately reddened, with E(B-V)~0.2-0.3. We find that the surface density of red quasars rises sharply with faintness, comprising up to 17% of blue quasars at the same apparent K-band flux limit.

We estimate that to reach more heavily reddened quasars (i.e., E(B-V)>~0.5) at z>2 and a depth of K=17, we would need to survey at least ~2.5 times more area.

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Catalogue records · 2

Topics

Stated by source
Infrared · Optical · Radio
Inferred from text
Image 65% · Stellar astronomy and planetary systems 77%
Provenance · 1 source records, 12 field assertions
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IVOA Registry (Virtual Observatory)ivo://cds.vizier/j/apj/778/12713 d agoJSON v1
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concepts[modality].ivoa_waveband:radiosource · IVOA Registryconnector:ivoa_registry@1.0.0
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