The Transition from "Normal" to "Broad Absorption Line Quasar" of Ton 34

TL;DR

This paper reports the recent emergence of a high-velocity broad absorption line outflow in the quasar Ton 34, suggesting such outflows may be common but only observable when aligned with our line of sight.

Contribution

It documents the first observation of a BAL outflow appearing in less than 8 years, highlighting the transient nature of quasar winds.

Findings

Outflow velocity ranges from ~5,000 to 26,000 km/s.

Absorption trough appeared between 1981 and 2006.

The outflow likely crosses our line of sight, revealing hidden quasar winds.

Abstract

We report the emergence of a high velocity, broad absorption line outflow in the luminous quasar Ton 34, at z=1.928. The outflow is detected through an ultraviolet CIV broad absorption line, in a spectrum obtained in January 2006 by the Sloan Digital Sky Survey. No absorption trough was present in two different spectra acquired in 1981 at Las Campanas and Palomar observatories, indicating the emergence of the outflow in less than ~8 yr (rest-frame). The absorption line spans a velocity range from ~5,000-26,000 km s-1}, and resembles typical troughs found in Broad Absorption Line quasars (BALQSOs). We measure a balnicity index >600 (tough this value might be an underestimation due to a conservativeplacing of the continuum). The absorption trough is likely saturated, with the absorbing gas covering ~25% of the emitting region. We explore different scenarios for the emergence of this outflow, and find an existing wind moving across our line of sight to the source as the most likely explanation. This indicates that high velocity outflows (producing broad absorption troughs in BALQSOs) might be ubiquitous in quasars, yet only become observable when the wind accidentally crosses our line vision to the central source.