Spectroscopic Observations of the Outflowing Wind in the Lensed Quasar SDSS J1001+5027

TL;DR

This study uses spectroscopic observations of a gravitationally lensed quasar to investigate the physical properties and variability of outflowing gas clouds near the quasar, revealing insights into wind structure and intervening absorbers.

Contribution

First detailed spectroscopic analysis of a lensed quasar's outflow wind constraining gas cloud properties and variability over multiple epochs.

Findings

Detected differences in CIV BAL profiles between images and epochs.

Estimated gas cloud rotational velocity ≥ 18,000 km/s and distance ≤ 0.06 pc from the quasar.

Observed variability and velocity shear in an MgII system indicating a possible intervening galaxy.

Abstract

We performed spectroscopic observations of the small-separation lensed quasar SDSS J1001+5027, whose images have an angular separation $\theta \sim 2.^{\!\!\prime\prime}86$, and placed constraints on the physical properties of gas clouds in the vicinity of the quasar (i.e., in the outflowing wind launched from the accretion disk). The two cylinders of sight to the two lensed images go through the same region of the outflowing wind and they become fully separated with no overlap at a very large distance from the source ($\sim 330$ pc). We discovered a clear difference in the profile of the CIV broad absorption line (BAL) detected in the two lensed images in two observing epochs. Because the kinematic components in the BAL profile do not vary in concert, the observed variations cannot be reproduced by a simple change of ionization state. If the variability is due to gas motion around the background source (i.e., the continuum source), the corresponding rotational velocity is $v_{rot}\geq 18,000$ km/s, and their distance from the source is $r\leq 0.06$ pc assuming Keplerian motion. Among three MgII and three CIV NAL systems that we detected in the spectra, only the MgII system at $z_{abs} = 0.8716$ shows a hint of variability in its MgI profile on a rest-frame time scale of $\Delta t_{rest}$ $\leq 191$ days and an obvious velocity shear between the sightlines whose physical separation is $\sim 7$ kpc. We interpret this as the result of motion of a cosmologically intervening absorber, perhaps located in a foreground galaxy.