THE EXTENDED HIGH A ( V ) QUASAR SURVEY: SEARCHING FOR DUSTY ABSORBERS TOWARD MID-INFRARED-SELECTED QUASARS

Journal Article · Sun Nov 20 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/832/1/49· OSTI ID:22667186

Krogager, J. -K.; Noterdaeme, P. ^[1]; Fynbo, J. P. U.; Heintz, K. E.; Vestergaard, M. ^[2]; Geier, S. ^[3]; Ledoux, C. ^[4]; Møller, P. ^[5]; Venemans, B. P. ^[6]

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1. Institut d’Astrophysique de Paris, CNRS-UPMC, UMR7095, 98bis bd Arago, F-75014 Paris (France)
2. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø (Denmark)
3. Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife (Spain)
4. European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago 19 (Chile)
5. European Southern Observatory, Karl-Schwarzschildstrasse 2, D-85748 Garching bei München (Germany)
6. Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)

We present the results of a new spectroscopic survey for dusty intervening absorption systems, particularly damped Ly α absorbers (DLAs), toward reddened quasars. The candidate quasars are selected from mid-infrared photometry from the Wide-field Infrared Survey Explorer combined with optical and near-infrared photometry. Out of 1073 candidates, we secure low-resolution spectra for 108 using the Nordic Optical Telescope on La Palma, Spain. Based on the spectra, we are able to classify 100 of the 108 targets as quasars. A large fraction (50%) is observed to have broad absorption lines (BALs). Moreover, we find six quasars with strange breaks in their spectra, which are not consistent with regular dust reddening. Using template fitting, we infer the amount of reddening along each line of sight ranging from A ( V ) ≈ 0.1 to 1.2 mag (assuming a Small Magellanic Cloud extinction curve). In four cases, the reddening is consistent with dust exhibiting the 2175 Å feature caused by an intervening absorber, and for two of these, an Mg ii absorption system is observed at the best-fit absorption redshift. In the rest of the cases, the reddening is most likely intrinsic to the quasar. We observe no evidence for dusty DLAs in this survey. However, the large fraction of BAL quasars hampers the detection of absorption systems. Out of the 50 non-BAL quasars, only 28 have sufficiently high redshift to detect Ly α in absorption.

• OSTI ID: 22667186
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 832; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
COSMIC DUST
DETECTION
INFRARED SURVEYS
LYMAN LINES
MAGELLANIC CLOUDS
PHOTOMETRY
QUASARS
RED SHIFT
RESOLUTION
SPAIN
SPECTRA
TELESCOPES