Dust evolution processes constrained by extinction curves in nearby galaxies

TL;DR

This study investigates whether known dust evolution processes can explain the extinction curves observed in nearby galaxies, finding success for the Milky Way but challenges for the SMC and LMC that can be addressed with specific modifications.

Contribution

It demonstrates that the dust evolution model can reproduce the Milky Way extinction curve and explores modifications needed for SMC/LMC curves, advancing understanding of dust processes in galaxies.

Findings

Milky Way extinction curve explained by dust evolution processes

Models fail to reproduce SMC/LMC curves without modifications

Efficient dust processing, especially grain growth, is favored by extinction data

Abstract

Extinction curves, especially those in the Milky Way (MW), the Large Magellanic Cloud (LMC), and the Small Magellanic Cloud (SMC), have provided us with a clue to the dust properties in the nearby Universe. We examine whether or not these extinction curves can be explained by well known dust evolution processes. We treat the dust production in stellar ejecta, destruction in supernova shocks, dust growth by accretion and coagulation, and dust disruption by shattering. To make a survey of the large parameter space possible, we simplify the treatment of the grain size distribution evolution by adopting the `two-size approximation', in which we divide the grain population into small ($\lesssim 0.03~\mu$m) and large ($\gtrsim 0.03~\mu$m) grains. It is confirmed that the MW extinction curve can be reproduced in reasonable ranges for the time-scale of the above processes with a silicate-graphite mixture. This indicates that the MW extinction curve is a natural consequence of the dust evolution through the above processes. We also find that the same models fail to reproduce the SMC/LMC extinction curves. Nevertheless, this failure can be remedied by giving higher supernova destruction rates for small carbonaceous dust and considering amorphous carbon for carbonaceous dust; these modification fall in fact in line with previous studies. Therefore, we conclude that the current dust evolution scenario composed of the aforementioned processes is successful in explaining the extinction curves. All the extinction curves favor efficient interstellar processing of dust, especially, strong grain growth by accretion and coagulation.