Dusty winds clear JWST super-early galaxies

TL;DR

This study investigates how radiatively-driven outflows may explain the dust-free nature of super-early galaxies observed by JWST, revealing a correlation between Eddington ratio and dust content across high redshifts.

Contribution

It provides the first large-sample analysis linking Eddington ratio to dust clearing in galaxies at redshifts 6.5 to 16, supporting outflows as a key dust removal mechanism.

Findings

Strong anti-correlation between Eddington ratio and dust optical depth.

Eddington ratio increases with redshift.

High sSFR galaxies develop powerful outflows that clear dust.

Abstract

The JWST discovery of a number of super-early (redshift $z>10$), blue galaxies requires these systems to be essentially dust-free in spite of their large stellar masses. A possible explanation is that dust is evacuated by radiatively-driven outflows. We test this hypothesis by deriving the Eddington ratio $\lambda_E=L_{\rm bol}/L_{E}$, where $L_{\rm bol}$ is the bolometric luminosity produced by star-formation and possible black hole accretion, for 134 galaxies at $6.5< z <16$. We find a strong anti-correlation between $\lambda_E$ and dust UV optical depth, $\tau_{1500} \propto \lambda_E^{-0.63}$; also, $\lambda_E$ increases with redshift. We confirm that galaxies exceeding a specific star formation rate ${\rm sSFR} > 13\, \rm Gyr^{-1}$ develop powerful outflows clearing the galaxy from its dust. This result is supported by ALMA dust continuum non-detections in three super-early systems.