Constraining Variable High Velocity Winds from Broad Absorption Line Quasars with Multi-Epoch Spectroscopy

TL;DR

This study uses multi-epoch spectroscopy to analyze variability in broad absorption line quasars, providing insights into the size, location, and dynamics of high-velocity outflows near supermassive black holes.

Contribution

It presents new multi-epoch spectroscopic data of BAL quasars with varied cadences, constraining outflow properties through observed variability patterns.

Findings

Significant BAL variability observed at 1 and 2 year timescales.

Variability constrains the size and location of outflowing gas.

Non-BAL quasars show no comparable variability.

Abstract

Broad absorption line (BAL) quasars probe the high velocity gas ejected by luminous accreting black holes. BAL variability timescales place constraints on the size, location, and dynamics of the emitting and absorbing gas near the supermassive black hole. We present multi-epoch spectroscopy of seventeen BAL QSOs from the Sloan Digital Sky Survey (SDSS) using the Fred Lawrence Whipple Observatory's 1.5m telescope's FAST Spectrograph. These objects were identified as BALs in SDSS, observed with Chandra, and then monitored with FAST at observed-frame cadences of 1, 3, 9, 27, and 81 days, as well as 1 and 2 years. We also monitor a set of non-BAL quasars with matched redshift and luminosity as controls. We identify significant variability in the BALs, particularly at the 1 and 2 year cadences, and use its magnitude and frequency to constrain the outflows impacting the broad absorption line region.