# The JCMT Nearby Galaxies Legacy Survey -- XI. -- Environmental Variations in the Atomic and Molecular Gas Radial Profiles of Nearby Spiral Galaxies

## TL;DR

This study compares the atomic and molecular gas distributions in spiral galaxies within and outside the Virgo cluster, revealing environmental effects like gas truncation and enhanced central H2 in Virgo galaxies, affecting star formation.

## Contribution

It provides the first detailed comparison of gas radial profiles in Virgo and non-Virgo spiral galaxies, highlighting environmental impacts on gas distribution and star formation efficiency.

## Key findings

- Virgo galaxies have truncated HI disks.
- Virgo galaxies show enhanced central H2 distribution.
- Star formation efficiency is lower in Virgo galaxies.

## Abstract

We present an analysis of the radial profiles of a sample of 43 HI-flux selected spiral galaxies from the Nearby Galaxies Legacy Survey (NGLS) with resolved James Clerk Maxwell Telescope (JCMT) CO $J=3-2$ and/or Very Large Array (VLA) HI maps. Comparing the Virgo and non-Virgo populations, we confirm that the HI disks are truncated in the Virgo sample, even for these relatively HI-rich galaxies. On the other hand, the H$_{2}$ distribution is enhanced for Virgo galaxies near their centres, resulting in higher H$_{2}$ to HI ratios and steeper H$_{2}$ and total gas radial profiles. This is likely due to the effects of moderate ram pressure stripping in the cluster environment, which would preferentially remove low density gas in the outskirts while enhancing higher density gas near the centre. Combined with H$\alpha$ star formation rate data, we find that the star formation efficiency (SFR/H$_{2}$) is relatively constant with radius for both samples, but Virgo galaxies have a $\sim40\%$ lower star formation efficiency than non-Virgo galaxies.