Extremely red quasars from SDSS, BOSS and WISE: classification of optical spectra
| Autor: | Isabelle Pâris, W. Niel Brandt, Donald P. Schneider, Rachael M. Alexandroff, Carolin Villforth, Nadia L. Zakamska, Adam D. Myers, Michael A. Strauss, Gordon T. Richards, Fred Hamann, Guilin Liu, Jenny E. Greene, Nicholas P. Ross |
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| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Astrophysics::High Energy Astrophysical Phenomena Population Continuum (design consultancy) FOS: Physical sciences Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences 0103 physical sciences Emission spectrum OVV quasar education 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Line (formation) Luminous infrared galaxy Physics education.field_of_study 010308 nuclear & particles physics Astrophysics::Instrumentation and Methods for Astrophysics Astronomy Astronomy and Astrophysics Quasar Astrophysics - Astrophysics of Galaxies Redshift Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | Ross, N, Hamann, F, Zakamska, N L, Richards, G T, Villforth, C, Strauss, M A, Greene, J E, Alexandroff, R M, Brandt, W N, Liu, G, Myers, A D, Paris, I & Schneider, D P 2015, ' Extremely red quasars from SDSS, BOSS and WISE: classification of optical spectra ', Monthly Notices of the Royal Astronomical Society . https://doi.org/10.1093/mnras/stv1710 Ross, N P, Hamann, F, Zakamska, N L, Richards, G T, Villforth, C, Strauss, M A, Greene, J E, Alexandroff, R, Brandt, W N, Liu, G, Myers, A D, Paris, I & Schneider, D P 2015, ' Extremely red quasars from SDSS, BOSS and WISE : classification of optical spectra ', Monthly Notices of the Royal Astronomical Society, vol. 453, no. 4, pp. 3932-3952 . https://doi.org/10.1093/mnras/stv1710 |
| DOI: | 10.1093/mnras/stv1710 |
| Popis: | Quasars with extremely red infrared-to-optical colours are an interesting population that can test ideas about quasar evolution as well as orientation, obscuration and geometric effects in the so-called AGN unified model. To identify such a population we match the quasar catalogues of the Sloan Digital Sky Survey (SDSS), the Baryon Oscillation Spectroscopic Survey (BOSS) to the Wide-Field Infrared Survey Explorer (WISE) to identify quasars with extremely high infrared-to-optical ratios. We identify 65 objects with r(AB)-W4(Vega)>14 mag (i.e., F_nu(22um)/F_nu(r) > ~1000). This sample spans a redshift range of 0.282.6 objects that are detected in the W4-band but not W1 or W2 (i.e., W1W2-dropouts). The SDSS/BOSS spectra show that the majority of the objects are reddened Type 1 quasars, Type 2 quasars (both at low and high redshift) or objects with deep low-ionization broad absorption lines (BALs) that suppress the observed r-band flux. In addition, we identify a class of Type 1 permitted broad-emission line objects at z~2-3 which are characterized by emission line rest-frame equivalent widths (REWs) of >~150Ang , much larger than those of typical quasars. In particular, 55% (45%) of the non-BAL Type 1s with measurable CIV in our sample have REW(CIV) > 100 (150)Ang, compared to only 5.8% (1.3%) for non-BAL quasars in BOSS. These objects often also have unusual line ratios, such as very high NV/Ly-alpha ratios. These large REWs might be caused by suppressed continuum emission analogous to Type 2 quasars; however, there is no obvious mechanism in standard Unified Models to suppress the continuum without also obscuring the broad emission lines. Comment: 21 pages, 3 tables, 19 figures. Published in MNRAS. Moderate changes from the v1 |
| Databáze: | OpenAIRE |
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