Variation of dust properties with cosmic time implied by radiative torque disruption

TL;DR

This paper proposes that increasing radiation intensity at higher redshifts causes smaller dust grains through radiative torque disruption, affecting extinction curves and potentially resolving observational tensions in cosmology.

Contribution

It introduces the concept of radiative torque disruption (RATD) as a mechanism for evolving dust properties with redshift, supported by modeling extinction curves and grain size distributions.

Findings

Dust grains become smaller at higher redshift due to RATD.

Extinction curves become steeper with increasing redshift.

Low R_V values from RATD can explain observed anomalous extinction in high-z galaxies.

Abstract

Dust properties within a galaxy are known to change from the diffuse medium to dense clouds due to increased local gas density. However, the question of whether dust properties change with redshift remains elusive. In this paper, using the fact that the mean radiation intensity of the interstellar medium (ISM) of star-forming galaxies increases with redshift, we show that dust properties should change due to increasing efficiency of rotational disruption by radiative torques, an effect named RAdiative Torque Disruption (RATD). We first show that, due to RATD, the size distribution of interstellar dust varies with redshift, such as dust grains become smaller at higher $z$. We model the extinction curves and find that the curve becomes steeper with increasing redshift. The ratio of total-to-selective extinction, $R_{V}$, decreases with redshift and achieves low values of $R_{V}\sim 1.5-2.5$ for grains having a composite structure. We also find that dust properties change with the local gas density due to RATD, but the change is dominated by the radiation field for the diffuse ISM. The low values of $R_{V}$ implied by RATD of interstellar dust could reproduce anomalous dust extinction observed toward type Ia supernovae (SNe Ia) and Small Magellanic Cloud (SMC)-like extinction curves with a steep far-UV rise toward high-z galaxies. Fluctuations in $R_{V}$ due to interstellar turbulence and varying radiation intensity may resolve the tension in measurements of the Hubble constant using SNe Ia. We finally discuss the implications of evolving dust properties for high-z astrophysics.