Molecular Gas Distribution in Barred and Non-Barred Galaxies along the Hubble Sequence

TL;DR

This study surveys molecular gas in 68 nearby galaxies, analyzing how its central concentration varies with galaxy type and bar presence, revealing that galaxy morphology influences gas distribution more than bars do.

Contribution

It provides a comprehensive analysis of molecular gas distribution across a wide range of galaxy types, highlighting the dominant role of Hubble type over bars in gas concentration.

Findings

Early type galaxies have higher central molecular gas concentration.

Hubble type correlates with molecular gas distribution more than bar presence.

The survey includes 166 galaxies, expanding previous datasets.

Abstract

We present results from a survey of 12CO(J=1-0) spectra obtained for the central regions of 68 nearby galaxies at an angular resolution of 16 arcseconds using the Nobeyama Radio Observatory 45m telescope, aimed at characterizing the properties of star forming molecular gas. Combined with similar resolution observations in the literature, the compiled sample set of 166 galaxies span a wide range of galactic properties. NGC 4380, which was previously undetected in CO, was detected. This initial paper of a series will focus on the data and the gaseous properties of the samples, and particularly on the degree of central concentration of molecular gas in a range of morphological types, from early (S0/Sa) to late (Sd/Sm) galaxies with and without bars. The degree of molecular central concentration in the central kiloparsec, compared to the central several kiloparsecs of galaxies, is found to vary smoothly with Hubble type, so that early type galaxies show larger central concentration. The comparison of barred and non-barred galaxies within early and late type galaxies suggest that difference in Hubble type, representing the effect of bulges, is the more important factor in concentrating gas into the central regions than bars.