Kinematic signatures of AGN feedback in moderately powerful radio galaxies atz~ 2 observed with SINFONI

Abstract

Most successful galaxy formation scenarios now postulate that the intense star formation in massive, high-redshift galaxies during their major growth period was truncated when powerful AGNs launched galaxy-wide outflows of gas that removed large parts of the interstellar medium. SINFONI imaging spectroscopy of the most powerful radio galaxies at z ∼ 2 show clear signatures of such winds, but are too rare to be good representatives of a generic phase in the evolution of all massive galaxies at high redshift. Here we present SINFONI imaging spectroscopy of the rest-frame optical emission-line gas in 12 radio galaxies at redshifts ∼2. Our sample spans a range in radio power that is intermediate between the most powerful radio galaxies with known wind signatures at these redshifts and vigorous starburst galaxies, and are about two orders of magnitude more common than the most powerful radio galaxies. Thus, if AGN feedback is a generic phase of massive galaxy evolution for reasonable values of the AGN duty cycle, these are just the sources where AGN feedback should be most important. Our sources show a diverse set of gas kinematics ranging from regular velocity gradients with amplitudes of Δv = 200−400 km s −1 consistent with rotating disks to very irregular kinematics with multiple velocity jumps of a few 100 km s −1 . Line widths are generally high, typically around FWHM = 800 km s −1 , more similar to the more powerful high-z radio galaxies than mass-selected samples of massive high-z galaxies without bright AGNs, and consistent with the velocity range expected from recent hydrodynamic models. A broad Hα line in one target implies a black hole mass of a few 10 9 M . Velocity offsets of putative satellite galaxies near a few targets suggest dynamical masses of a few 10 11 M for our sources, akin to the most powerful high-z radio galaxies. Ionized gas masses are 1−2 orders of magnitude lower than in the most powerful radio galaxies, and the extinction in the gas is relatively low, up to A V ∼ 2 mag. The ratio of line widths, σ, to bulk velocity, v, is so large that even the gas in galaxies with regular velocity fields is unlikely to be gravitationally bound. It is unclear, however, whether the large line widths are due to turbulence or unresolved, local outflows as are sometimes observed at low redshifts. We compare our sources with sets of radio galaxies at low and high redshift, finding that they may have more in common with gas-rich nearby radio galaxies with similar jet power than with the most powerful high-z radio galaxies. Comparison of the kinetic energy with the energy supply from the AGNs through jet and radiation pressure suggests that the radio source still plays a dominant role for feedback, consistent with low-redshift radio-loud quasars.

Characterizing the WISE-selected heavily obscured quasar population with optical spectroscopy from the Southern African Large Telescope

“…These values are roughly consistent with similar spectroscopic studies of [OIII] emission (e.g. Vega Beltrán et al 2001;Mullaney et al 2013;Collet et al 2016;Harrison et al 2016;Sun et al 2017). We note that most of these works cite the w 80 measurement for their objects, the velocity difference between the 10th and 90th percentiles of the emission line, roughly the FWHM of a single Gaussian fit.…”

“…We note that most of these works cite the w 80 measurement for their objects, the velocity difference between the 10th and 90th percentiles of the emission line, roughly the FWHM of a single Gaussian fit. Our broad component FWHM therefore overestimate these measurements but likely still satisfy the w 80 > 600 km s −1 criterion outlined in Collet et al (2016) and Liu et al (2013) indicative of either ionised outflows or highly turbulent material. These objects are potentially of interest for further study with highly resolved imaging to understand their host properties and the location of the turbulent or outflowing material.…”

The MIXR sample: AGN activity versus star formation across the cross-correlation ofWISE, 3XMM, and FIRST/NVSS

“…The first step could be an assessment of how many sources with radiatively driven winds also have radio emission, as recent evidence seems to point out to a frequent coexistence of both (see e.g. Nesvadba et al 2008;Collet et al 2016;Harrison et al 2015), but we still need to assess whether in the most luminous sources the radio emission is actually produced by jets and lobes or just by particles accelerated in wind-driven shocks (e.g. Nims et al 2015;Zakamska et al 2016), and what fraction of the observed outflows is actually produced by star formation, rather than the AGN (Sarzi et al 2016).…”

Relativistic jet feedback in high-redshift galaxies – I. Dynamics

“…Binney & Tabor 1995;Soker et al 2001;Gaspari et al 2012). However, relativistic jets are also expected to be one of the major drivers of feedback on galactic scale, as supported by several observational evidences of jet-ISM interaction (a few recent works being Mahony et al 2016;Collet et al 2016;Dasyra et al 2015;Morganti et al 2015;Ogle et al 2014;Dasyra et al 2014;Morganti et al 2013;Lanz et al 2015b;Tadhunter et al 2014;Nesvadba et al 2011Nesvadba et al , 2008Nesvadba et al , 2007. However, only a few theoretical papers (Sutherland & Bicknell 2007;Gaibler et al 2011;Wagner & Bicknell 2011b;Gaibler et al 2012;Wagner et al 2012) have addressed the question of how a relativistic jet interacts with a multi-phase ISM of the host galaxy, and over what scales such interactions are relevant.…”