Resolving the Multiple Component Outflows in PG 1211+143: I. The Fe-K Absorption Structure and UFO Forest

TL;DR

This study uses high-resolution X-ray spectroscopy to analyze the complex Fe-K absorption features in quasar PG 1211+143, revealing multiple ultra-fast outflows that suggest a common structure in near Eddington-luminosity sources.

Contribution

First detailed high-resolution spectral analysis of multiple UFO components in PG 1211+143, identifying a 'UFO forest' structure similar to PDS 456, advancing understanding of quasar outflows.

Findings

Six distinct UFO velocity components detected

Outflows have narrow line widths indicating terminal velocities

Mass outflow rate comparable to Eddington accretion rate

Abstract

We present the initial high-resolution X-ray spectroscopic observations of the Fe-K absorption structure in the luminous nearby quasar PG 1211+143, utilizing the X-ray Imaging and Spectroscopy Mission (XRISM). The primary objective is to characterize the Fe-K absorption features due to Ultra-Fast Outflow (UFO) in this Eddington-luminosity source. Observations were conducted with XRISM's Resolve and Xtend instruments, complemented by simultaneous data from XMM-Newton and NuSTAR. A historically bright phase was captured. The Resolve spectra clearly reveal a prominent P Cygni profile and resolves the Fe-K absorption into six distinct velocity components, ranging from $v = -0.074c$ to $-0.405c$. A similar superposition of multiple UFOs has been reported in PDS~456, suggesting that such a ``UFO forest'' structure may be a common feature of near Eddington-luminosity sources. Some UFO components exhibit narrow line widths of approximately $\sigma \sim 200\,\mathrm{km\,s^{-1}}$, which may indicate that the outflows have reached their terminal velocities, thereby resulting in a smaller velocity shear. The mass outflow rate is estimated to be $\dot{M}_\mathrm{out} \sim 1~M_{\odot}~\text{yr}^{-1}$, which is of the order of the Eddington accretion rate. This suggests a physically plausible scenario where the outflow is a significant channel for mass ejection.