The Physical Conditions of the Intrinsic N V Narrow Absorption Line Systems of Three Quasars

TL;DR

This study uses photoionization models to analyze intrinsic N V narrow absorption lines in three quasars, revealing high metallicity, high ionization, and partial coverage, with implications for early galaxy metal enrichment.

Contribution

It provides detailed physical conditions of intrinsic N V absorbers in quasars, highlighting their high metallicity and ionization, and discusses implications for galaxy evolution.

Findings

High metallicity (>10 times solar) in absorbers.

High ionization parameter (log U ~ 0).

Mass outflow rate estimated to be less than a few solar masses per year.

Abstract

We employ detailed photoionization models to infer the physical conditions of intrinsic narrow absorption line systems found in high resolution spectra of three quasars at z=2.6-3.0. We focus on a family of intrinsic absorbers characterized by N V lines that are strong relative to the Ly-alpha lines. The inferred physical conditions are similar for the three intrinsic N V absorbers, with metallicities greater than 10 times the solar value (assuming a solar abundance pattern), and with high ionization parameters (log U ~ 0). Thus, we conclude that the unusual strength of the N V lines results from a combination of partial coverage, a high ionization state, and high metallicity. We consider whether dilution of the absorption lines by flux from the broad-emission line region can lead us to overestimate the metallicities and we find that this is an unlikely possibility. The high abundances that we infer are not surprising in the context of scenarios in which metal enrichment takes place very early on in massive galaxies. We estimate that the mass outflow rate in the absorbing gas (which is likely to have a filamentary structure) is less than a few solar masses per year under the most optimistic assumptions, although it may be embedded in a much hotter, more massive outflow.