Observations of feedback from radio-quiet quasars – II. Kinematics of ionized gas nebulae

The prevalence and energetics of quasar feedback is a major unresolved problem in galaxy formation theory. In this paper, we present Gemini Integral Field Unit observations of ionized gas around 11 luminous, obscured, radio-quiet quasars at z ∼ 0. 5 out to ∼15 kpc from the quasar; specifically, we measure the kinematics and morphology of O iii λ5007 Å emission. The round morphologies of the nebulae and the large line-of-sight velocity widths (with velocities containing 80 per cent of the emission as high as 103 km s−1) combined with relatively small velocity difference across them (from 90 to 520 km s−1) point towards wide-angle quasi-spherical outflows. We use the observed velocity widths to estimate a median outflow velocity of 760 km s−1, similar to or above the escape velocities from the host galaxies. The line-of-sight velocity dispersion declines slightly towards outer parts of the nebulae (by 3 per cent kpc−1 on average). The majority of nebulae show blueshifted excesses in their line profiles across most of their extents, signifying gas outflows. For the median outflow velocity, we find |Ė ₊₈₍| between 4 × 1044 and 3 × 1045 erg s−1 and |Ṁ| between 2 × 103 and 2 × 104 M⊙ yr−1. These values are large enough for the observed quasar winds to have a significant impact on their host galaxies. The median rate of converting bolometric luminosity to kinetic energy of ionized gas clouds is ∼2 per cent. We report four new candidates for ‘superbubbles’ – outflows that may have broken out of the denser regions of the host galaxy.