Toward a Complete Picture of Quasar Outflows: from BALs to mini-BALs
Abstract
Accretion disk outflows are important for galaxy evolution and an integral part of the quasar phenomenon, but they remain poorly understood. In order to construct a more complete picture of the quasar phenomenon, we need to understand the full range of different types of quasar outflows and how they correlate with one another. We examine seven SDSS quasars with CIV 1548,1551 Å outflow lines that span a range from strong BALs to weak mini-BALs. They have moderate redshifts (1.68 < z < 1.91) to minimize contamination from the Lyα forest while still allowing measurements of CIV from the ground and other important lines like OVI 1031,1038 Å and PV 1118,1128 Å with HST. We use archival SDSS and BOSS spectra in combination with HST COS G230L observations and multi-epoch ground-based spectra obtained at the MDM and Kitt Peak observatories to measure a variety of ions across the rest UV wavelength range. Our preliminary analysis shows OVI is present and stronger than CIV in all seven quasars. In one case, we detect an OVI mini-BAL with no accompanying CIV, requiring a highly-ionized outflow. In the strongest BAL quasar, we detect resolved PV doublet absorption that requires PV optical depths > 3 and in outflow gas with a line-of-sight covering fraction of only 0.27. Thus, the total column density in this outflow component might exceed N_H > 1023 cm-2 which has important consequences for the outflow kinetic energies and feedback. The multi-epoch CIV data reveal CIV outflow variability in all seven quasars; four become weaker, one becomes stronger, and two become both stronger and weaker over the different epochs. This variability happens across time scales of ~1-12 years in the quasar rest frames which is consistent with outflow locations close to the central quasar engines. We use these and other results to constrain the ionization, column density, and location of the absorbers with the broader goals of understanding accretion physics, the integrated structure of quasar outflows, and the impact a quasar has on its host galaxy.
- Publication:
-
American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016
- Bibcode:
- 2016AAS...22741704M