Publication: Peculiar emission line spectra of core extremely red BOSS quasars at z ~ 2-3: orientation and/or evolution?
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2020-02
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Villar Martín, M.
Perna, M
Humphrey, A.
Castro Rodríguez, N,
Binette, L.
Mateos, S.
Cabrera Lavers, A.
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Abstract
Context. Core extremely red quasars (core ERQ) have been proposed to represent an intermediate evolutionary phase in which a heavily obscured quasar blows out the circumnuclear interstellar medium with very energetic outflows before it becomes an optical quasar.
Aims. We investigate whether the properties of core ERQ fit the AGN orientation-based unification scenario.
Methods. We revised the general UV and optical emission line properties of core ERQ in the context of the orientation-based scenario. We used diagnostic diagrams based on UV emission line ratios and UV-to-optical line kinematic information to compare the physical and kinematic gas properties of core ERQ with those of other luminous narrow- and broad-line AGN. In particular, we provide a revised comparison of the [OIII] kinematics in 21 core ERQ (20 from Perrotta et al. 2019, MNRAS, 488, 4126 and SDSS J171420.38+414815.7, based on GTC EMIR near-infrared spectroscopy) with other samples of quasars with matching luminosity with the aim of evaluating whether core ERQ host the most extreme [OIII] outflows.
Results. The UV line ratios suggest that the physical properties (e.g., density and metallicity) of the ionised gas in core ERQ are similar to those observed in the broad-line region of blue nitrogen-loud quasars. The [OIII] outflow velocities of core ERQ are on average consistent with those of very luminous blue type 1 quasars, although extreme outflows are much more frequent in core ERQ. These similarities can be explained in the context of the AGN unification model under the assumption that core ERQ are viewed with an intermediate orientation between type 2 (edge-on) and type 1 (face-on) quasars. Conclusions. We propose that core ERQ are very luminous but otherwise normal quasars viewed at an intermediate orientation. This orientation allows a direct view of the outer part of the large broad-line region from which core ERQ UV line emission originates; the extreme [OIII] outflow velocities are instead a consequence of the very high luminosity of core ERQ.
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© ESO 2020. We thank José Acosta Pulido for valuable scientific discussions and the anonymous referee for the thorough revision of the manuscript. Thanks also to Yue Shen for making his QSO1 near-infrared spectra available. Partly based on observations made with the GTC telescope and the EMIR instrument at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (program GTC14-19A). We thank the GTC staff for their support with the observations. We thank Joel Vernet for providing the high z NLRG composite spectrum. M. V. M. acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grants AYA2015- 64346-C2-2-P and PGC2018-094671-B-I00 (MCIU/AEI/FEDER,UE). M. P. is supported by the Programa Atracción de Talento de la Comunidad de Madrid via grant 2018-T2/TIC-11715. M. P. acknowledges support from the Spanish Ministerio de Economía y Competitividad through the grant ESP2017- 83197-P. AH acknowledges FCT Fellowship SFRH/BPD/107919/2015; Support from European Community Programme (FP7/2007-2013) under grant agreement No. PIRSES-GA-2013-612701 (SELGIFS); Support from FCT through national funds (PTDC/FIS-AST/3214/2012 and UID/FIS/04434/2013), and by FEDER through COMPETE (FCOMP-01-0124-FEDER-029170) and COMPETE2020 (POCI-01-0145-FEDER-007672). S. M. acknowledges financial support through grant AYA2016-76730-P (MINECO/FEDER). This research has made use of: (1) the VizieR catalogue access tool, CDS, Strasbourg, France. The original description of the VizieR service was published in Ochsenbein et al. A&AS, 143, 23; (2) data from Sloan Digital Sky Survey. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/; (3) the Cosmology calculator by Wright (2006); (4) the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.