On saturation of betatron acceleration of dust particles behind shock fronts

TL;DR

This paper investigates how the mirror instability behind supernova shock fronts can saturate betatron acceleration of dust particles, significantly reducing their nonthermal destruction efficiency compared to traditional estimates.

Contribution

It introduces the role of mirror instability in limiting dust destruction by betatron acceleration behind supernova shocks, providing a new perspective on dust survival.

Findings

Nonthermal dust destruction efficiency can be an order of magnitude lower due to mirror instability.

The instability develops rapidly, affecting dust destruction in shocks with velocities 100-300 km/s.

Traditional estimates overstate dust destruction by neglecting instability effects.

Abstract

Possible saturation of betatron acceleration of dust particles behind strong shock fronts from supernovae is considered. It is argued that the efficiency of the nonthermal dust destruction should be substantially lower than the value estimated from a traditional description of betatron acceleration of dust grains behind radiative shock waves. The inhibition of the nonthermal destruction can be connected with the mirror instability developed in the dust component behind strong shocks with the velocity 3 times exceeding the Alfv\'en speed. The instability develops on characteristic time scales much shorter the age of a supernova remnant, thus its influence on the efficiency of dust destruction can be substantial: in the range of shock velocities 100 km s$^{-1}<v_s<300$ km s$^{-1}$ the destruction efficiency can be an order of magnitude lower that normally estimated.