English

Luminous WISE-selected Obscured, Unobscured, and Red Quasars in Stripe 82

Astrophysics of Galaxies 2018-07-18 v1 Cosmology and Nongalactic Astrophysics

Abstract

We present a spectroscopically complete sample of 147 infrared-color-selected AGN down to a 22 μ\mum flux limit of 20 mJy over the \sim270 deg2^2 of the SDSS Stripe 82 region. Most of these sources are in the QSO luminosity regime (Lbol1012LL_{\rm bol} \gtrsim 10^{12} L_\odot) and are found out to z3z\simeq3. We classify the AGN into three types, finding: 57 blue, unobscured Type-1 (broad-lined) sources; 69 obscured, Type-2 (narrow-lined) sources; and 21 moderately-reddened Type-1 sources (broad-lined and E(BV)>0.25E(B-V) > 0.25). We study a subset of this sample in X-rays and analyze their obscuration to find that our spectroscopic classifications are in broad agreement with low, moderate, and large amounts of absorption for Type-1, red Type-1 and Type-2 AGN, respectively. We also investigate how their X-ray luminosities correlate with other known bolometric luminosity indicators such as [O III] line luminosity (L[OIII]L_{\rm [OIII]}) and infrared luminosity (L6μmL_{6 \mu{\rm m}}). While the X-ray correlation with L[OIII]L_{\rm [OIII]} is consistent with previous findings, the most infrared-luminous sources appear to deviate from established relations such that they are either under-luminous in X-rays or over-luminous in the infrared. Finally, we examine the luminosity function (LF) evolution of our sample, and by AGN type, in combination with the complementary, infrared-selected, AGN sample of Lacy et al. (2013), spanning over two orders of magnitude in luminosity. We find that the two obscured populations evolve differently, with reddened Type-1 AGN dominating the obscured AGN fraction (\sim30%) for L5μm>1045L_{5 \mu{\rm m}} > 10^{45} erg s1^{-1}, while the fraction of Type-2 AGN with L5μm<1045L_{5 \mu{\rm m}} < 10^{45} erg s1^{-1} rises sharply from 40% to 80% of the overall AGN population.

Keywords

Cite

@article{arxiv.1805.06961,
  title  = {Luminous WISE-selected Obscured, Unobscured, and Red Quasars in Stripe 82},
  author = {E. Glikman and M. Lacy and S. LaMassa and D. Stern and S. G. Djorgovski and M. J. Graham and T. Urrutia and L. Lovdal and M. Crnogorcevic and H. Daniels-Koch and C. B. Hundal and C. M. Urry and E. L. Gates and S. Murray},
  journal= {arXiv preprint arXiv:1805.06961},
  year   = {2018}
}

Comments

Accepted for publication in ApJ; 35 pages, 22 Figures, 8 Tables