The SINFONI survey of powerful radio galaxies at z ~ 2: Jet-driven AGN feedback during the Quasar Era

Abstract

We present VLT/SINFONI imaging spectroscopy of the rest-frame optical emission lines of warm ionized gas in 33 powerful radio galaxies at redshifts z 2, which are excellent sites to study the interplay of rapidly accreting active galactic nuclei and the interstellar medium of the host galaxy in the very late formation stages of massive galaxies. Our targets span two orders of magnitude in radio size (2−400 kpc) and kinetic jet energy (a few 10 46 − almost 10 48 erg s −1 ). All sources have complex gas kinematics with broad line widths up to ∼1300 km s −1 . About half have bipolar velocity fields with offsets up to 1500 km s −1 and are consistent with global back-to-back outflows. The others have complex velocity distributions, often with multiple abrupt velocity jumps far from the nucleus of the galaxy, and are not associated with a major merger in any obvious way. We present several empirical constraints that show why gas kinematics and radio jets seem to be physically related in all galaxies of the sample. The kinetic energy in the gas from large scale bulk and local outflow or turbulent motion corresponds to a few 10 −3 to 10 −2 of the kinetic energy output of the radio jet. In galaxies with radio jet power > ∼ 10 47 erg s −1 , the kinetic energy in global back-to-back outflows dominates the total energy budget of the gas, suggesting that bulk motion of outflowing gas encompasses the global interstellar medium. This might be facilitated by the strong gas turbulence, as suggested by recent analytical work. We compare our findings with recent hydrodynamic simulations, and discuss the potential consequences for the subsequent evolution of massive galaxies at high redshift. Compared with recent models of metal enrichment in high-z AGN hosts, we find that the gas-phase metallicities in our galaxies are lower than in most low-z AGN, but nonetheless solar or even super-solar, suggesting that the ISM we see in these galaxies is very similar to the gas from which massive low-redshift galaxies formed most of their gas. This further highlights that we are seeing these galaxies near the end of their active formation phase.

The MOSDEF Survey: The Prevalence and Properties of Galaxy-wide AGN-driven Outflows at z ∼ 2

“…molecular and neutral). For example, Nesvadba et al (2017) find that that there is ∼ 5 − 50 times more molecular gas than ionized gas in high-redshift radio galaxies with outflows. Moreover, the observed Hα or Hβ flux does not account for the entire mass of the ionized outflows, since we observe only the blueshifted wing in the emission line.…”

Evidence for Higher Black Hole Spin in Radio-loud Quasars

“…For low-z AGN with high radio luminosity (L rad 10 24 W Hz −1 ) no clear evidence for broadened narrow line widths is seen in large, statistical studies (Mullaney et al 2013;Coziol et al 2017). In high-z powerful radio galaxies, hosting luminous obscured quasars, ionized gas outflows traced by the [O III] line are frequently seen (Nesvadba et al 2006(Nesvadba et al , 2008(Nesvadba et al , 2017, in particular for compact small-scale radio sources (Nesvadba et al 2007;Kim et al 2013). While the interpretation that the outflows in these sources are driven by the jet is very plausible, signatures of powerful outflows seem to be common in the general luminous RQ quasar population as well, in particular at high-z (e.g.…”

Host galaxies of high-redshift extremely red and obscured quasars

“…The redshifts of their objects are lower than ours, but they have three radio galaxies at z = 1.8−2.5 which we include in our qualitative comparisons: 3C257, 3C326.1 and 3C454.1. In these three cases we assume that the nucleus does not contribute to the integrated photometry due to the type 2 spectrum in the rest-frame optical (e.g., Nesvadba et al 2017 for 3C257).…”