Quasar outflows and AGN feedback in the extreme UV: HST/COS observations of HE 0238−1904★

Abstract

Spectroscopic observations of quasar outflows at rest-frame 500-1000 Angstrom\nhave immense diagnostic power. We present analyses of such data, where\nabsorption troughs from three important ions are measured: first, O IV and O\nIV* that allow us to obtain the distance of high ionization outflows from the\nAGN; second, Ne VIII and Mg X that are sensitive to the very high ionization\nphase of the outflow. Their inferred column densities, combined with those of\ntroughs from O VI, N IV, and H I, yield two important results: 1) The outflow\nshows two ionization phases, where the high ionization phase carries the bulk\nof the material. This is similar to the situation seen in x-ray warm absorber\nstudies. Furthermore, the low ionization phase is inferred to have a volume\nfilling factor of 10^(-5)-10^(-6). 2) From the O IV to O IV* column density\nratio, and the knowledge of the ionization parameter, we determine a distance\nof 3000 pc. from the outflow to the central source. Since this is a typical\nhigh ionization outflow, we can determine robust values for the mass flux and\nkinetic luminosity of the outflow: 40 solar masses per year and 10^45 ergs/s,\nrespectively, where the latter is roughly equal to 1% of the bolometric\nluminosity. Such a large kinetic luminosity and mass flow rate measured in a\ntypical high ionization wind suggests that quasar outflows are a major\ncontributor to AGN feedback mechanisms.\n