Quasar Outflow Contribution to AGN Feedback: Observations of QSO SDSS J0838+2955

Abstract

We present a detailed analysis of the Astrophysical Research Consortium 3.5 m telescope spectrum of QSO SDSS J0838+2955. The object shows three broad absorption line (BAL) systems at 22,000, 13,000, and 4900 km s(-1) blueshifted from the systemic redshift of z = 2.043. Of particular interest is the lowest velocity system that displays absorption from low-ionization species such as MgII, Al II, Si II, Si II*, Fe II, and Fe II*. Accurate column densities were measured for all transitions in this lowest velocity BAL using an inhomogeneous absorber model. The ratio of column densities of Si II* and Fe II* with respect to their ground states gave an electron number density of log n(e) (cm(-3)) = 3.75 +/- 0.22 for the outflow. Photoionization modeling with careful regards to chemical abundances and the incident spectral energy distribution predicts an ionization parameter of log U(H) = -1.93 +/- 0.21 and a hydrogen column density of log N(H) (cm(-2)) = 20.80 +/- 0.28. This places the outflow at 3.3(-1.0)(+1.5) kpc from the central active galactic nucleus (AGN). Assuming that the fraction of solid angle subtended by the outflow is 0.2, these values yield a kinetic luminosity of (4.5(-1.8)(+3.1)) x 10(45) erg s(-1), which is (1.4(-0.6))% the bolometric luminosity of the QSO itself. Such large kinetic luminosity suggests that QSO outflows are a major contributor to AGN feedback mechanisms.