Cold molecular gas in the Perseus cluster core - Association with X-ray cavity, Halpha filaments and cooling flow -

TL;DR

This study maps cold molecular gas in the Perseus cluster core, revealing its association with optical filaments, X-ray cavities, and potential fueling of star formation, highlighting the role of AGN activity in cooling flows.

Contribution

First detailed CO(2-1) map of cold molecular gas in Perseus core linking it to filaments, X-ray cavities, and AGN-driven processes.

Findings

Cold gas concentrated at galaxy center and along filaments

CO emission associated with X-ray cavity rims

Gas likely a mix of infalling and uplifted material

Abstract

Cold molecular gas has been recently detected in several cooling flow clusters of galaxies where huge optical nebulosities often stand. These optical filaments are tightly linked to the cooling flow and to the related phenomena, like the rising bubbles of relativistic plasma, fed by the radio jets. We present here a map in the CO(2-1) rotational line of the cold molecular gas associated with some Halpha filaments surrounding the central galaxy of the Perseus cluster: NGC 1275. The map, extending to about 50 kpc (135 arcsec) from the center of the galaxy, has been made with the 18-receiver array HERA, at the focus of the IRAM 30m telescope. Although most of the cold gas is concentrated to the center of the galaxy, the CO emission is also clearly associated to the extended filaments conspicuous in ionised gas and could trace a possible reservoir fueling the star formation there. Some of the CO emission is also found where the X-ray gas could cool down more efficiently: at the rims of the central X-ray cavity (where the hot gas is thought to have been pushed out and compressed by the central AGN expanding radio lobes). The CO global kinematics does not show any rotation in NGC 1275. The cold gas is probably a mixture of gas falling down on the central galaxy and of uplifted gas dragged out by a rising bubble in the intracluster medium. As recenlty suggested in other cluster cores, the cold gas peculiar morphology and kinematics argue for the picture of an intermittent cooling flow scenario where the central AGN plays an important role.