Directly tracing cool filamentary accretion over >100 kpc into the interstellar medium of a quasar host at z=1

TL;DR

This study presents the discovery of the longest cool filamentary gas accretion structure into a quasar host at z=1, combining spectroscopic observations to reveal complex inflow and outflow dynamics over hundreds of kiloparsecs.

Contribution

It provides the first detailed observation of a giant filamentary accretion structure connecting halo gas to a quasar host, revealing complex kinematics and inflow mechanisms at high redshift.

Findings

Longest cool filament observed to date (>120 kpc)

Detected complex inflow and outflow kinematics around the quasar

Inflow rate is insufficient to sustain quasar luminosity, indicating variable accretion

Abstract

We report the discovery of giant (50-100 kpc) [O II] emitting nebulae with the Multi-Unit Spectroscopic Explorer (MUSE) in the field of TXS 0206-048, a luminous quasar at z=1.13. Down-the-barrel UV spectra of the quasar show absorption at velocities coincident with those of the extended nebulae, enabling new insights into inflows and outflows around the quasar host. One nebula exhibits a filamentary morphology extending over 120 kpc from the halo toward the quasar and intersecting with another nebula surrounding the quasar host with a radius of 50 kpc. This is the longest cool filament observed to-date and arises at higher redshift and in a less massive system than those in cool-core clusters. The filamentary nebula has line-of-sight velocities >300 km/s from nearby galaxies but matches that of the nebula surrounding the quasar host where they intersect, consistent with accretion of cool inter- or circum-galactic medium or cooling hot halo gas. The kinematics of the nebulae surrounding the quasar host are unusual and complex, with redshifted and blueshifted spiral-like structures. The emission velocities at 5-10 kpc from the quasar match those of inflowing absorbing gas observed in UV spectra of the quasar. Together, the extended nebulae and associated redshifted absorption represent a compelling case of cool, filamentary gas accretion from halo scales into the extended interstellar medium and toward the nucleus of a massive quasar host. The inflow rate implied by the combined emission and absorption constraints is well below levels required to sustain the quasar's radiative luminosity, suggesting anisotropic or variable accretion.