The Herschel Virgo Cluster Survey: III. A constraint on dust grain lifetime in early-type galaxies

TL;DR

This study constrains the lifetime of dust grains in early-type galaxies to less than approximately 46 million years, highlighting the rapid destruction of dust in hot, passive galaxy environments and the necessity of external dust acquisition.

Contribution

It provides the first direct upper limit on dust grain survival time in passive early-type galaxies using Herschel and Spitzer data.

Findings

Passive ETGs not detected by Herschel suggest rapid dust destruction.

Detected ETGs likely acquire dust through interactions, not internal production.

Dust survival time in ETGs is constrained to less than 46 million years.

Abstract

Passive early-type galaxies (ETGs) provide an ideal laboratory for studying the interplay between dust formation around evolved stars and its subsequent destruction in a hot gas. Using Spitzer-IRS and Herschel data we compare the dust production rate in the envelopes of evolved AGB stars with a constraint on the total dust mass. Early-type galaxies which appear to be truly passively evolving are not detected by Herschel. We thus derive a distance independent upper limit to the dust grain survival time in the hostile environment of ETGs of < 46 +/- 25 Myr for amorphous silicate grains. This implies that ETGs which are detected at far-infrared wavelengths have acquired a cool dusty medium via interaction. Given likely time-scales for ram-pressure stripping, this also implies that only galaxies with dust in a cool (atomic) medium can release dust into the intra-cluster medium.