MULTIWAVELENGTH OBSERVATIONS OF RADIO-QUIET QUASARS WITH WEAK EMISSION LINES

Journal Article · Mon Sep 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/721/1/562· OSTI ID:21464849

Plotkin, Richard M ^[1]; Anderson, Scott F; MacLeod, Chelsea L ^[2]; Brandt, W N; Schneider, Donald P ^[3]; Diamond-Stanic, Aleksandar M; Xiaohui, Fan ^[4]; Shemmer, Ohad ^[5]

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1. Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands)
2. Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
3. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)
4. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
5. Department of Physics, University of North Texas, Denton, TX 76203 (United States)

We present radio and X-ray observations, as well as optical light curves, for a subset of 26 BL Lac candidates from the Sloan Digital Sky Survey (SDSS) lacking strong radio emission and with z < 2.2. Half of these 26 objects are shown to be stars, galaxies, or absorbed quasars. We conclude that the other 13 objects are active galactic nuclei (AGNs) with abnormally weak emission features; 10 of those 13 are definitively radio quiet, and, for those with available optical light curves, their level of optical flux variability is consistent with radio-quiet quasars. We cannot exclude the possibility that some of these 13 AGNs lie on the extremely radio-faint tail of the BL Lac distribution, but our study generally supports the notion that all BL Lac objects are radio-loud. These radio-quiet AGNs appear to have intrinsically weak or absent broad emission line regions (BELRs), and, based on their X-ray properties, we argue that some are low-redshift analogs to weak line quasars (WLQs). SDSS BL Lac searches are so far the only systematic surveys of the SDSS database capable of recovering such exotic low-redshift WLQs. There are 71 more z < 2.2 radio-quiet BL Lac candidates already identified in the SDSS, but not considered here, and many of those might be best unified with WLQs as well. Future studies combining low- and high-redshift WLQ samples will yield new insight on our understanding of the structure and formation of AGN BELRs.

• OSTI ID: 21464849
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 721; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BL LACERTAE OBJECTS
COSMIC RADIO SOURCES
EMISSION
GALAXIES
GALAXY NUCLEI
QUASARS
RED SHIFT
STARS