Kinematics of C iv and [O iii] emission in luminous high-redshift quasars

Coatman, Liam, Hewett, Paul C., Banerji, Manda, Richards, Gordon T., Hennawi, Joseph F. and Prochaska, J. Xavier (2019) Kinematics of C iv and [O iii] emission in luminous high-redshift quasars. Monthly Notices Of The Royal Astronomical Society, 486 (4), 5335-5348. (doi:10.1093/mnras/stz1167). (In Press)

Abstract

We characterize ionized gas outflows using a large sample of ≃330 high-luminosity [45.5 < log(L_bol/erg s⁻¹) < 49.0], high-redshift (1.5 ≲ z ≲ 4.0) quasars via their [O III]λλ4960,5008 emission. The median velocity width of the [O III] emission line is 1540 kms⁻¹, increasing with increasing quasar luminosity. Broad, blue-shifted wings are seen in the [O III] profiles of ≃42 per cent of the sample. Rest-frame ultraviolet spectra with well-characterized C IVλ1550 emission-line properties are available for more than 210 quasars, allowing an investigation of the relationship between the broad-line region (BLR) and narrow-line region (NLR) emission properties. The [O III] blueshift is correlated with C IV blueshift, even when the dependence of both quantities on quasar luminosity has been taken into account. A strong anticorrelation between the [O III] equivalent width (EW) and C IV blueshift also exists. Furthermore, [O III] is very weak, with EW < 1 Å  in ≃10 per cent of the sample, a factor of 10 higher compared to quasars at lower luminosities and redshifts. If the [O III] emission originates in an extended NLR, the observations suggest that quasar-driven winds are capable of influencing the host-galaxy environment out to kilo-parsec scales. The mean kinetic power of the ionized gas outflows is then 10^44.7 erg s⁻¹, which is ≃0.15 per cent of the bolometric luminosity of the quasar. These outflow efficiencies are broadly consistent with those invoked in current active galactic nuclei feedback models.

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Contributors

Author: Manda Banerji

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