Survival of dust in super-dusty galaxies at redshifts $z \approx 5-8$

TL;DR

This paper investigates how dust survives in early galaxies at redshifts 5 to 8, focusing on the effects of supernova shocks and proposing mechanisms for dust preservation.

Contribution

It presents arguments that dust cooling can inhibit sputtering in supernova shocks, explaining the high dust masses observed in early galaxies.

Findings

Dust cooling may prevent sputtering in supernova shocks.

High dust masses in early galaxies are challenging to explain with standard SN dust yields.

Proposed mechanisms could account for dust survival in galaxies at z>5.

Abstract

The presence of dust in galaxies at redshifts $z>5$ is commonly connected with core collapse supernovae (SN). Galaxies with exceptionally large dust mass, of order of $1 - 3$\% of the galaxy stellar mass, have been detected during the last decade. The required SN dust yield is $\gtrsim 1~M_\odot$ per supernova, which is comparable to the theoretically predicted maximum. However, the reverse shock (RS) penetrating the SN ejecta significantly destroy the dust particles nucleating there through sputtering. The resulting net dust mass injected into the interstellar gas after processing by the RS turns out to be $\lesssim 0.1~M_\odot$ per SN. This makes the explanation of the existence of $z>5$ galaxies with dust masses as high as $M_d\gtrsim (0.01-0.03)M_\ast$ a challenging one. In this paper we present arguments in favor of an efficient inhibition of the sputtering behind the RS, caused by a strong radiation cooling from the dust in the supernova ejecta.