CO in late-type galaxies within the central region of Abell 1367

TL;DR

This study investigates the molecular gas content and distribution in 19 late-type galaxies within Abell 1367, revealing environmental effects like H_2 deficiency and signs of ram pressure stripping through CO observations.

Contribution

First detailed CO (J=1-0 and 2-1) survey of late-type galaxies in Abell 1367, linking molecular gas properties to environmental influences and gas distribution anomalies.

Findings

H_2 deficiency correlates with redder colors and higher HI deficiency.

Detected abnormal molecular gas distributions in some galaxies, indicating environmental interactions.

Evidence of ram pressure stripping affecting molecular gas in CGCG 097-079.

Abstract

We present CO (J = 1 - 0) and CO (J = 2 - 1) spectra for 19 bright, late-type galaxies (spirals) in the central region of the galaxy cluster Abell 1367 (z = 0.02) from observations made with the IRAM 30 - m telescope. All 19 spirals were observed at the position of their optical center and for a subset, at multiple positions. For each spiral the integrated CO (J = 1 - 0) intensity from the central pointing, in few cases supplemented with intensities from offset pointings, was used to estimate its molecular hydrogen mass and H_2 deficiency. Accepting the considerable uncertainties involved in determining H_2 deficiencies, spirals previously identified by us to have redder colours and higher HI deficiencies as a result of environmental influence, were found to be more H_2 deficient compared to members of the sample in less advanced evolutionary states. For eight of the observed spirals multiple pointing observations were made to investigate the distribution of their molecular gas. For these spirals we fitted Gaussians to the CO intensities projected in a line across the galaxy. In two cases, CGCG 097-079 and CGCG 097-102(N), the offset between the CO and optical intensity maxima was significantly larger than the pointing uncertainty and the FWHMs of the fits were significantly greater than those of the other spirals, irrespective of optical size. Both signatures are indicators of an abnormal molecular gas distribution. In the case of CGCG 097-079, which is considered an archetype for ram pressure stripping, our observations indicate the CO intensity maximum lies ~ 15.6 +/- 8.5 arcsec (6 kpc) NW of the optical centre at the same projected position as the HI intensity maximum.