An HI study of three long-tailed irregular galaxies in the cluster Abell1367

TL;DR

This study investigates the distribution and movement of hydrogen gas in three irregular galaxies within cluster Abell 1367, revealing ram pressure effects and gas dynamics that influence galaxy evolution in dense environments.

Contribution

It provides higher sensitivity and spectral resolution observations of H I gas in these galaxies, highlighting ram pressure effects and gas retention contrary to expectations.

Findings

H I gas shows sharper gradients near tails in two galaxies.

H I emission extends less far than radio and Hα tails.

20-30% of H I mass accumulates downstream due to ram pressure.

Abstract

We present the results on the distribution and kinematics of H$\sc{i}$ gas with higher sensitivity and in one case of higher spectral resolution as well than reported earlier, of three irregular galaxies CGCG 097073, 097079 and 097087 (UGC 06697) in the cluster Abell 1367. These galaxies are known to exhibit long (50$-$75 kpc) tails of radio continuum and optical emission lines (H$\alpha$) pointing away from the cluster centre and arcs of starformation on the opposite sides of the tails. These features as well as the H{\sc i} properties, with two of the galaxies (CGCG 097073 and 097079) exhibiting sharper gradients in H{\sc i} intensity on the side of the tails, are consistent with the H{\sc i} gas being affected by the ram pressure of the intracluster medium. However the H{\sc i} emission in all the three galaxies extends to much smaller distances than the radio-continuum and H$\alpha$ tails, and are possibly still bound to the parent galaxies. Approximately 20$-$30 per cent of the H{\sc i} mass is seen to accumulate on the downstream side due to the effects of ram pressure.