The Herschel Virgo Cluster Survey: X.The relationship between cold dust and molecular gas content in Virgo spirals

TL;DR

This study examines the relationship between cold dust and molecular gas in Virgo spiral galaxies, revealing that dust correlates more strongly with total gas and is less affected by cluster interactions than atomic gas.

Contribution

It provides new insights into how dust and molecular gas relate to each other and respond to environmental effects in galaxy clusters, especially in HI deficient spirals.

Findings

CO flux correlates tightly with far-infrared fluxes.

Dust mass correlates more strongly with total gas than with atomic or molecular gas alone.

Dust-to-gas ratio increases with HI deficiency but remains constant in highly HI deficient galaxies.

Abstract

Using the far-infrared emission, as observed by the Herschel Virgo Cluster Survey (HeViCS), and the integrated HI and CO brightness, we infer the dust and total gas mass for a magnitude limited sample of 35 metal rich spiral galaxies in Virgo. The CO flux correlates tightly and linearly with far-infrared fluxes observed by Herschel. Molecules in these galaxies are more closely related to cold dust rather than to dust heated by star formation or to optical/NIR brightness. We show that dust mass establishes a stronger correlation with the total gas mass than with the atomic or molecular component alone. The dust-to-gas ratio increases as the HI deficiency increases, but in highly HI deficient galaxies it stays constant. Dust is in fact less affected than atomic gas by weak cluster interactions, which remove most of the HI gas from outer and high latitudes regions. Highly disturbed galaxies, in a dense cluster environment, can instead loose a considerable fraction of gas and dust from the inner regions of the disk keeping constant the dust-to-gas ratio. There is evidence that the molecular phase is also quenched. This quencing becomes evident by considering the molecular gas mass per unit stellar mass. Its amplitude, if confirmed by future studies, highlights that molecules are missing in Virgo HI deficient spirals, but to a somewhat lesser extent than dust.