A very extended molecular web around NGC 1275

TL;DR

This study reports the first detection of CO emission in the extended Halpha filaments of NGC 1275, revealing a large molecular gas reservoir likely linked to AGN feedback and galaxy core fueling.

Contribution

It provides the first observational evidence of molecular gas in the distant filaments of NGC 1275 and links their formation to AGN feedback mechanisms.

Findings

Detected CO lines up to 50 kpc from galaxy center

Molecular gas mass in filaments is about 10% of total molecular content

Molecular web penetrates to within 2 kpc of the nucleus

Abstract

We present the first detection of CO emission lines in the Halpha filaments at distances as far as 50 kpc from the centre of the galaxy NGC 1275. This gas is probably dense (>=10E3 cm-3). However, it is not possible to accurately determine the density and the kinetic temperature of this relatively warm gas (Tkin~20-500K) with the current data only. The amount of molecular gas in the filaments is large 10E9 Msun (assuming a Galactic N(H2)/Ico ratio). This is 10% of the total mass of molecular gas detected in this cD galaxy. This gas has large-scale velocities comparable to those seen in Halpha. The origin of the filaments is still unclear, but their formation is very likely linked to the AGN positive feedback (Revaz et al., 2008) that regulates the cooling of the surrounding X-ray-emitting gas as suggested by numerical simulations. We also present high-resolution spectra of the galaxy core. The spatial characteristics of the double-peaked profile suggest that the molecular web of filaments and streamers penetrates down to radii of less than 2 kpc from the central AGN and eventually feed the galaxy nucleus. The mass of gas inside the very central region is ~10E^9 Msun, and is similar to the mass of molecular gas found in the filaments.