Abstract Luminous quasars are powerful targets to investigate the role of feedback from supermassive black holes (BHs) in regulating the growth phases of BHs themselves and of their host galaxies, up to the highest redshifts. Here we investigate the cosmic evolution of the occurrence and kinematics of BH-driven outflows, as traced by broad absorption line (BAL) features, due to the C iv ionic transition. We exploit a sample of 1935 quasars at z = 2.1–6.6 with bolometric luminosity log( L bol /erg s −1 ) ≳ 46.5, drawn from the Sloan Digital Sky Survey and from the X-Shooter legacy survey of Quasars at the Reionization Epoch (XQR-30). We consider rest-frame optical bright quasars to minimize observational biases due to quasar selection criteria. We apply a homogeneous BAL-identification analysis, based on employing composite template spectra to estimate the quasar intrinsic emission. We find a BAL quasar fraction close to 20% at z ∼ 2–4, while it increases to almost 50% at z ∼ 6. The velocity and width of the BAL features also increase at z ≳ 4.5. We exclude the possibility that the redshift evolution of the BAL properties is due to differences in terms of quasar luminosity and accretion rate. These results suggest significant BH feedback occurring in the 1 Gyr old universe, likely affecting the growth of BHs and, possibly, of their host galaxies, as supported by models of early BH and galaxy evolution.
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Direct detection of quasar feedback via the Sunyaev–Zeldovich effect
The nature and energetics of feedback from thermal winds in quasars can be constrained via observations of the Sunyaev–Zeldovich Effect (SZE) induced by the bubble of thermal plasma blown into the intergalactic medium by the quasar wind. In this letter, we present evidence that we have made the first detection of such a bubble, associated with the hyperluminous quasar HE 0515-4414. The SZE detection is corroborated by the presence of extended emission line gas at the same position angle as the wind. Our detection appears on only one side of the quasar, consistent with the SZE signal arising from a combination of thermal and kinetic contributions. Estimates of the energy in the wind allow us to constrain the wind luminosity to the lower end of theoretical predictions, ∼0.01 per cent of the bolometric luminosity of the quasar. However, the age we estimate for the bubble, ∼0.1 Gyr, and the long cooling time, ∼0.6 Gyr, means that such bubbles may be effective at providing feedback between bursts of quasar activity.
more » « less- NSF-PAR ID:
- 10485811
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society: Letters
- Volume:
- 483
- Issue:
- 1
- ISSN:
- 1745-3925
- Format(s):
- Medium: X Size: p. L22-L27
- Size(s):
- ["p. L22-L27"]
- Sponsoring Org:
- National Science Foundation
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