The variable, fast soft X-ray wind in PG 1211+143

TL;DR

This study analyzes high-resolution soft X-ray spectra of PG 1211+143, revealing a variable, two-phase wind with high outflow velocity, significant mass loss, and ionization changes responding to continuum flux.

Contribution

It provides detailed evidence of a variable, two-phase soft X-ray wind in PG 1211+143, with insights into its structure, variability, and mass outflow rate, advancing understanding of quasar winds.

Findings

Detection of blue-shifted absorption lines indicating a wind at -0.06c

Identification of two ionization zones with variable absorption

Estimated mass outflow rate close to the Eddington limit

Abstract

The analysis of a series of seven observations of the nearby ($z=0.0809$) QSO, PG 1211+143, taken with the Reflection Grating Spectrometer (RGS) on-board XMM-Newton in 2014, are presented. The high resolution soft X-ray spectrum, with a total exposure exceeding 600 ks, shows a series of blue-shifted absorption lines, from the He and H-like transitions of N, O and Ne, as well as from L-shell Fe. The strongest absorption lines are all systematically blue-shifted by $-0.06c$, originating in two absorption zones, from low and high ionization gas. Both zones are variable on timescales of days, with the variations in absorber opacity effectively explained by either column density changes or by the absorber ionization responding directly to the continuum flux. We find that the soft X-ray absorbers probably exist in a two-phase wind, at a radial distance of $10^{17}-10^{18}$ cm from the black hole, with the lower ionization gas as denser clumps embedded within a higher ionization outflow. The overall mass outflow rate of the soft X-ray wind may be as high as $2{\rm M}_{\odot}$ yr$^{-1}$, close to the Eddington rate for PG 1211+143 and similar to that previously deduced from the Fe K absorption.