A 100 kpc nebula associated with the "Teacup" fading quasar

TL;DR

This paper reports the discovery of a large, ionized nebula around the 'Teacup' quasar, revealing insights into the circumgalactic medium and quasar fading history through detailed spectroscopic analysis.

Contribution

It presents the first detailed observation of a 100 kpc nebula associated with a fading quasar, highlighting the role of AGN illumination in revealing circumgalactic gas.

Findings

The nebula is among the largest around active galaxies at any redshift.

Detection of coronal emission lines at large distances supports the fading quasar scenario.

The nebula's properties suggest it is part of the host galaxy's circumgalactic medium, enriched by tidal debris.

Abstract

We report the discovery of a ~100 kpc ionized nebula associated with the radio quiet type 2 quasar (QSO2) nicknamed the "Teacup" (z=0.085). The giant nebula is among the largest known around active galaxies at any z. We propose that it is part of the circumgalactic medium (CGM) of the QSO2 host, which has been populated with tidal debris by galactic interactions. This rich gaseous medium has been rendered visible due to the illumination by the powerful active nucleus (AGN). Subsolar abundances (~0.5Z(sun)) are tentatively favored by AGN photoionization models. We also report the detection of coronal emission (Fe+6) from the NE bubble, at ~9 kpc from the AGN. The detection of coronal lines at such large distances from the AGN and the [NII]/Halpha, [SII]/Halpha, [OI]/Halpha optical emission line ratios of the giant nebula are consistent with the fading quasar scenario proposed by Gagne et al. (2014). The fading rate appears to have been faster in the last ~46,000 yr. Deep wide field integral field spectroscopy of giant nebulae around powerful AGN such as the "Teacup's" with instruments such as MUSE on VLT opens up a way to detect and study the elusive material from the CGM around massive active galaxies thanks to the illumination by the luminous AGN.