Volume 617, September 2018
|Number of page(s)||24|
|Published online||24 September 2018|
The WISSH quasars project
IV. Broad line region versus kiloparsec-scale winds
INAF – Osservatorio Astronomico di Roma,
Via Frascati 33,
2 Università degli Studi di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Roma, Italy
3 Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, 85748 Garching, Germany
4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
5 Dipartimento di Fisica, Università degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
6 Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
7 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
8 Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, Firenze, Italy
9 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
10 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
11 INAF – Istituto di Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, 00133 Rome, Italy
12 Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
13 INAF – Osservatorio Astronomico di Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
14 INAF – Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, 34143 Trieste, Italy
15 European Southern Observatory (ESO), Alonso de Cordova 3107, Vitacura, Santiago, Chile
16 Department of Astronomy, University of Maryland, College Park, MD 20742 USA
17 NASA/Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 USA
Accepted: 8 February 2018
Winds accelerated by active galactic nuclei (AGNs) are invoked in the most successful models of galaxy evolution to explain the observed physical and evolutionary properties of massive galaxies. Winds are expected to deposit energy and momentum into the interstellar medium (ISM), thus regulating both star formation and supermassive black hole (SMBH) growth. We undertook a multiband observing program aimed at obtaining a complete census of winds in a sample of WISE/SDSS selected hyper-luminous (WISSH) quasars (QSOs) at z ≈ 2–4. We analyzed the rest-frame optical (i.e. LBT/LUCI and VLT/SINFONI) and UV (i.e. SDSS) spectra of 18 randomly selected WISSH QSOs to measure the SMBH mass and study the properties of winds both in the narrow line region (NLR) and broad line region (BLR) traced by blueshifted or skewed [OIII] and CIV emission lines, respectively. These WISSH QSOs are powered by SMBH with masses ≳109 M⊙ accreting at 0.4 < λEdd < 3.1. We found the existence of two subpopulations of hyper-luminous QSOs characterized by the presence of outflows at different distances from the SMBH. One population (i.e. [OIII] sources) exhibits powerful [OIII] outflows, a rest-frame equivalent width (REW) of the CIV emission REWCIV ≈ 20–40 Å, and modest CIV velocity shift (vCIVpeak) with respect to the systemic redshift (vCIVpeak <~ 2000 km s−1). The second population (i.e. Weak [OIII] sources), representing ~70% of the analyzed WISSH QSOs, shows weak or absent [OIII] emission and an extremely large blueshifted CIV emission (vCIVpeak up to ~8000 km s−1 and REWCIV <~ 20 Å). We propose two explanations for the observed behavior of the strength of the [OIII] emission in terms of the orientation effects of the line of sight and ionization cone. The dichotomy in the presence of BLR and NLR winds could be likely due to inclination effects considering a polar geometry scenario for the BLR winds. In a few cases these winds are remarkably as powerful as those revealed in the NLR in the [OIII] QSOs (Ėkin ~ 1044−45 erg s−1). We also investigated the dependence of these CIV winds on fundamental AGN parameters such as bolometric luminosity (LBol), Eddington ratio (λEdd), and UV-to-X-ray continuum slope (αOX). We found a strong correlation with LBol and an anti-correlation with αOX whereby the higher the luminosity, the steeper the ionizing continuum described by means of αOX and the larger the blueshift of the CIV emission line. Finally, the observed dependence vCIVpeak ∝ LBol0.28 ± 0.04 is consistent with a radiatively-driven-winds scenario, where a strong UV continuum is necessary to launch the wind and a weakness of the X-rayemission is fundamental to prevent overionization of the wind itself.
Key words: galaxies: active / galaxies: nuclei / quasars: emission lines / quasars: general / quasars: supermassive black holes / ISM: jets and outflows
© ESO 2018
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.