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

Abstract

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 similar to 0.5 out to similar to 15 kpc from the quasar; specifically, we measure the kinematics and morphology of [O III]lambda 5007 angstrom 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 quasispherical 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. E-kin between 4 x 10(44) and 3 x 10(45) erg s(-1) and. M between 2 x 10(3) and 2 x 10(4)M(circle dot) 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 similar to 2 per cent. We report four new candidates for ‘superbubbles’ - outflows that may have broken out of the denser regions of the host galaxy.