Dust Heating by Low-mass Stars in Massive Galaxies at z<1

TL;DR

This study investigates how low-mass stars heat dust in massive galaxies at redshifts 0.2 to 1.0, revealing that such heating influences galaxy evolution by inhibiting star formation through reduced molecular hydrogen formation.

Contribution

The paper introduces a novel method to estimate dust temperature from stellar radiation fields and applies it to distant galaxies, linking dust heating to passive galaxy evolution.

Findings

Passively evolving galaxies with M* > 10^{10} Msun have dust temperatures > 20 K.

Higher dust temperatures correlate with a higher fraction of passive galaxies.

Dust heating by low-mass stars impacts molecular hydrogen formation and galaxy quenching.

Abstract

Using the Hubble Space Telescope/Wide Field Camera 3 imaging data and multi-wavelength photometric catalog, we investigated the dust temperature of passively evolving and star-forming galaxies at 0.2<z<1.0 in the CANDELS fields. We estimated the stellar radiation field by low-mass stars from the stellar mass and surface brightness profile of these galaxies and then calculated their steady-state dust temperature. At first, we tested our method using nearby early-type galaxies with the deep FIR data by the Herschel Virgo cluster survey and confirmed that the estimated dust temperatures are consistent with the observed temperatures within the uncertainty. We then applied the method to galaxies at 0.2<z<1.0, and found that most of passively evolving galaxies with Mstar > 10^{10} Msun have a relatively high dust temperature of Tdust > 20 K, for which the formation efficiency of molecular hydrogen on the surface of dust grains in the diffuse ISM is expected to be very low from the laboratory experiments. The fraction of passively evolving galaxies strongly depends on the expected dust temperature at all redshifts and increases rapidly with increasing the temperature around Tdust ~ 20 K. These results suggest that the dust heating by low-mass stars in massive galaxies plays an important role for the continuation of their passive evolution, because the lack of the shielding effect of the molecular hydrogen on the UV radiation can prevent the gas cooling and formation of new stars.