On the dust abundance gradients in late-type galaxies: I. Effects of destruction and growth of dust in the interstellar medium

TL;DR

This paper provides theoretical insights into how supernova-driven destruction and interstellar dust growth influence the radial distribution of dust in late-type galaxies, suggesting dust-to-metals gradients as a diagnostic tool.

Contribution

It offers a theoretical framework linking dust destruction and growth processes to observable dust-to-metals gradients in galaxy disks.

Findings

Flat dust-to-metals gradient if no dust destruction occurs.

Flatter or equal dust-to-metals gradient compared to metallicity gradient with dust destruction.

Steeper dust-to-metals gradient indicates significant dust growth in the ISM.

Abstract

We present basic theoretical constraints on the effects of destruction by supernovae (SNe) and growth of dust grains in the interstellar medium (ISM) on the radial distribution of dust in late-type galaxies. The radial gradient of the dust-to-metals ratio is shown to be essentially flat (zero) if interstellar dust is not destroyed by SN shock waves and all dust is produced in stars. If there is net dust destruction by SN shock waves, the dust-to-metals gradient is flatter than or equal to the metallicity gradient (assuming the gradients have the same sign). Similarly, if there is net dust growth in the ISM, then the dust-to-metals gradient is steeper than or equal to the metallicity gradient. The latter result implies that if dust gradients are steeper than metallicity gradients, i.e., the dust-to-metals gradients are not flat, then it is unlikely dust destruction by SN shock waves is an efficient process, while dust growth must be a significant mechanism for dust production. Moreover, we conclude that dust-to-metals gradients can be used as a diagnostic for interstellar dust growth in galaxy discs, where a negative slope indicates dust growth.