Molecular gas along the old radio jets of the cluster-central type 2 quasar IRAS 09104+4109

TL;DR

This study maps molecular gas in the cluster-central quasar IRAS 09104+4109, revealing extended cold gas structures aligned with old radio jets, indicating ongoing cooling and star formation despite active galactic nucleus activity.

Contribution

First detailed NOEMA CO(2-1) mapping of molecular gas in a high-redshift cluster-central QSO, showing extensive cold gas aligned with radio jets and insights into ICM cooling processes.

Findings

Molecular gas extends up to ~55 kpc, comparable to Perseus cluster nebula.

Gas shows low velocity dispersion with no signs of outflow or infall.

ICM cooling appears unaffected by the QSO, fueling star formation and AGN reorientation.

Abstract

We present Northern Extended Millimeter Array (NOEMA) CO(2-1) maps of the z=0.4418 cluster-central QSO IRAS 09104+4109, which trace ~4.5x10^10 Msol of molecular gas in and around the galaxy. As in many low redshift cool core clusters, the molecular gas is located in a series of clumps extending along the old radio jets and lobes. It has a relatively low velocity dispersion (336 [+39,-35] km/s FWHM) and shows no velocity gradients indicative of outflow or infall. Roughly half the gas is located in a central clump on the northeast side of the galaxy, overlapping a bright ionized gas filament and a spur of excess X-ray emission, suggesting that this is a location of rapid cooling. The molecular gas is unusually extended, out to ~55 kpc radius, comparable to the scale of the filamentary nebula in the Perseus cluster, despite the much higher redshift of this system. The extent falls within the thermal instability radius of the intracluster medium (ICM), with t_cool/t_ff<25 and t_cool}/t_eddy~1 within ~70 kpc. Continuum measurements at 159.9 GHz from NOEMA and 850 micron from the JCMT SCUBA-2 show excess far infrared emission, which we interpret as free-free emission arising from the ongoing starburst. These observations suggest that ICM cooling is not strongly affected by the buried QSO, and that cooling from the ICM can build gas reservoirs sufficient to fuel quasar-mode activity and drive the reorientation of the central AGN.