QSO2 outflow characterization using data obtained with OSIRIS at the Gran Telescopio Canarias

Abstract

Ionized outflows are ubiquitous in non radio-loud obscured quasars (QSO2s) at different redshifts. We search for large-scale ionized outflows associated with six optically selected QSO2 (five non-radio-loud and one radio-loud) at $z\sim$ 0.2-0.5, targeting objects with extended radio structures. We have obtained OSIRIS/GTC optical long slit spectroscopy data for these six QSO2 with the slit located along the radio axis. We traced the gas kinematics with the [OIII]$\lambda$4959,5007 lines to investigate ionized outflows and characterize the dynamical state of the host galaxies. This second study has been complemented with previously published FORS2/VLT spectroscopic data of 13 more QSO2 at similar z. We identify ionized outflows in four out of the six QSO2 observed with the GTC. The outflows are spatially unresolved in two QSO2 and compact in a third (radial size of R=0.8$\pm$0.3 kpc). Of particular interest is the radio-quiet QSO2 SDSS 0741+3020 at z=0.47, associated with a giant $\sim$ 112 kpc nebula. An ionized outflow probably induced by the radio structures has been detected along the axis defined by the central $\sim$1\arcsec\ radio structure, extending up to at least $\sim$4 kpc from the active galactic nucleus (AGN). Turbulent gas ($\sigma\sim$130 km s$^{-1}$) has also been detected across the giant gas nebula up to $\sim$40 kpc from the AGN. This turbulence may have been induced by outflows triggered by the interaction between a so-far undetected large-scale radio source and the nebula. Regarding the dynamical state of the host galaxies, we find that the majority of the QSO2 show v/$\sigma<$ 1, implying that they are dominated by random motions (so-called dispersion-dominated systems). Most (17 of 19) fall in the area of the E/S0 galaxies in the dynamical diagram v/$\sigma$ versus $\sigma$. None are consistent with spiral or disk galaxies.