Rapidly varying Mg II broad absorption line in SDSS J133356.02+001229.1

TL;DR

This study documents rapid and dramatic variability in a high-velocity Mg II broad absorption line in a quasar, revealing insights into the dynamics and ionization conditions of quasar outflows over timescales of days to years.

Contribution

First detailed monitoring of rapid Mg II BAL variability in SDSS J133356.02+001229.1, constraining ionization and cloud dynamics in quasar outflows.

Findings

BAL trough re-emerged and nearly disappeared within months to years.

Velocity of BAL absorption remained stable, indicating no acceleration or deceleration.

Ionization parameter constrained from Mg II to Fe II ratio.

Abstract

We report the discovery of rapid variations of a high-velocity Mg ii broad absorption line (BAL) trough in the quasar SDSS J133356.02+001229.1 (zem ~ 0.9197). Vivek et al. (2012a) revealed the emergence and subsequent near disappearance of a BAL component in this source having an ejection velocity of ~ 28000 km s-1. Our further follow up studies with South African Large Telescope (SALT) reveal the dramatic nature of the absorption line variability in this source. The absorption line emerged again at the same velocity and nearly disappeared within the SALT observations. Our observations allow us to probe variability over timescales of the order of few days to 4.2 years in the QSO rest-frame. The observed velocity stability of BAL absorption does not point to any line of sight acceleration/deceleration of BAL clouds. The ionization parameter of the absorbing cloud is constrained from the column density ratio of Mg II to Fe II ground state absorption. In the absence of strong optical continuum variability, we suggest that photoionization driven BAL variability due to changes in the shielding, multiple streaming clouds across our line of sight in a co-rotating wind or a combination of both as possible explanations for the observed strong equivalent width variations.