Galactic-scale absorption outflow in the low-luminosity quasar IRAS F04250-5718: Hubble space telescope/cosmic origins spectrograph observations

Abstract

We present absorption line analysis of the outflow in the quasar IRAS F04250?5718. Far-ultraviolet data from the Cosmic Origins Spectrograph on board the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization ions (e.g., C iv, N v, and O vi) as well as low ionization ions (e.g., Cii and Si iii). We identify three kinematic components with central velocities ranging from ??50 to ??230 km s?1. Velocity-dependent, nonblack saturation is evident from the line profiles of the high ionization ions. From the non-detection of absorption from a metastable level of C ii, we are able to determine that the electron number density in the main component of the outflow is 30 cm?3. Photoionization analysis yields an ionization parameter log UH ? ?1.6 ± 0.2, which accounts for changes in the metallicity of the outflow and the shape of the incident spectrum. We also consider solutions with two ionization parameters. If the ionization structure of the outflow is due to photoionization by the active galactic nucleus, we determine that the distance to this component from the central source is 3 kpc. Due to the large distance determined for the main kinematic component, we discuss the possibility that this outflow is part of a galactic wind.