The WISSH quasars project VI. Fraction and properties of BAL quasars in the hyper-luminosity regime

Abstract

The WISSH quasars project aims at studying the nuclear and host galaxy properties of the most luminous quasars ($L_{bol}>10^{47}$ erg/s, $1.8<z<4.6$). Nuclear winds are manifested as UV broad ($\ge$ 2,000 km/s) absorption lines (BAL) in $\sim$ 15\% of quasars. We aim at studying the incidence and properties of such winds in the WISSH sample, to investigate possible differences with respect to lower luminosity AGN regimes. We collected optical spectra from the SDSS data release 12, and identified those showing absorption troughs in the region between \siiv and \civ emission lines. We find a higher observed fraction of \civ BAL quasars in the WISSH sample (24\%) with respect to previous catalogues (10-15\%). These WISSH BAL quasars are also characterized by a larger average BI ($\sim$4,000 km/s) and maximum velocity ($\sim$17,000 km/s). Moreover, for two objects we discovered BAL features bluewards of the \siiv peak, which can be associated to \civ absorption with velocity of 0.15c. Finally, we updated previous studies on the dependence of maximum outflow velocity upon bolometric luminosity, showing that BAL winds have intermediate properties compared to molecular/ionized winds and ultra fast outflows (UFOs). Finally, the radio properties of the WISSH BAL quasars as a whole are in line with those of samples at lower luminosities from previous studies. Our results suggest that the higher $L_{\mathrm{bol}}$ of the WISSH quasars likely favours the acceleration of BAL outflows and that their most likely driving mechanism is radiation pressure. Furthermore we estimate that the kinetic power associated to these winds in hyperluminous quasars is sufficient, for the highest column density and fastest winds, to provide efficient feedback onto the host galaxy.

Accepted for publication on A&A

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Cited by in corpus (22)

• The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release
• Widespread, strong outflows in XQR-30 quasars at the Reionisation epoch
• The WISSH QSOs project IX. Cold gas content and environment of luminous QSOs at z~2.4-4.7
• The most luminous blue quasars at $3.0<z<3.3$. I. A tale of two X-ray populations
• SUPER III. Broad Line Region properties of AGN at z$\sim$2
• On the importance of special relativistic effects in modelling ultra-fast outflows
• The Physical Properties of Low Redshift FeLoBAL Quasars. I. Spectral Synthesis Analysis of the BAL Outflows using $SimBAL$
• The fraction and kinematics of broad absorption line quasars across cosmic time
• The WISSH quasars project X. Discovery of a multi-component and highly-variable UV ultra-fast outflow in a z=3.6 quasar
• Speed limits for radiation driven SMBH winds
• Multi-phase black-hole feedback and a bright [CII] halo in a Lo-BAL quasar at $z\sim 6.6$
• The WISSH quasars project XI. The mean Spectral Energy Distribution and Bolometric Corrections of the most luminous quasars
• High-redshift quasars along the Main Sequence
• GA-NIFS: A galaxy-wide outflow in a Compton-thick mini-BAL quasar at z = 3.5 probed in emission and absorption
• Search for intrinsic NALs in BAL/mini-BAL quasar spectra
• [OIII] emission in z=2 quasars with and without Broad Absorption Lines
• Discovery and characterization of 25 new quasars at 4.6 < z < 6.9 from wide-field multi-band surveys
• The WISSH quasars project VII. Outflows and metals in the circumgalactic medium around the hyper-luminous z~3.6 quasar J1538+08
• The WISSH quasars project VII. The impact of extreme radiative field in the accretion disk and X-ray corona interplay
• Black hole-galaxy co-evolution and the role of feedback
• Efficient Identification of Broad Absorption Line Quasars using Dimensionality Reduction and Machine Learning
• Near-infrared spectroscopy of extreme BAL QSOs from the QUBRICS bright quasar survey