A Survey of Intrinsic Absorption in Active Galaxies using the Far Ultraviolet Spectroscopic Explorer

TL;DR

This survey of 72 active galaxies using FUSE identifies intrinsic UV absorption in about half of Seyfert 1s and quasars, providing insights into the covering factor and prevalence of absorbing gas.

Contribution

It is the largest high-resolution UV absorption survey of low-redshift AGN, offering new statistics on intrinsic absorption prevalence and covering factors.

Findings

Approximately 50% of Seyfert 1s and quasars show intrinsic UV absorption.

The global covering factor of absorbing gas is about 0.4.

This is the first large-scale high-resolution UV survey of intrinsic absorption in low-redshift AGN.

Abstract

We present a survey of 72 Seyfert galaxies and quasars observed by the it Far Ultraviolet Spectroscopic Explorer (FUSE). We have determined that 72 of 253 available active galactic nuclei (AGN) targets are viable targets for detection of intrinsic absorption lines. We examined these spectra for signs of intrinsic absorption in the O VI doublet (lambda 1031.9, 1037.6) and Lyman beta (lambda 1025.7). The fraction of Seyfert 1 galaxies and low-redshift quasars at z < 0.15 that show evidence of intrinsic UV absorption is ~50%, which is slightly lower than Crenshaw et al. (1999) found (60%) based on a smaller sample of Seyfert 1 galaxies observed with the Hubble Space Telescope (HST). With this new fraction we find a global covering factor of the absorbing gas with respect to the central nucleus of ~0.4. Our survey is to date the largest searching for intrinsic UV absorption with high spectral resolution, and is the first step toward a more comprehensive study of intrinsic absorption in low-redshift AGN.