ALMA observations of super-early galaxies: attenuation-free model predictions

TL;DR

This paper predicts the ALMA detectability of dust in super-early galaxies, testing a model where radiation-driven outflows eject dust, and provides specific flux estimates for the most distant known galaxy at redshift 14.32.

Contribution

It introduces a model predicting dust distribution and ALMA fluxes in super-early galaxies, aiding interpretation of JWST discoveries and guiding future observations.

Findings

Predicted ALMA flux for galaxy GS-z14-0 is around 14.9 μJy with fiducial parameters.

Higher dust content increases predicted flux up to 40.1 μJy.

Fainter fluxes are expected for other early galaxies due to lower star formation rates.

Abstract

The abundance and blue color of super-early (redshift $z>10$), luminous galaxies discovered by JWST can be explained if radiation-driven outflows have ejected their dust on kpc-scales. To test this hypothesis, we predict the ALMA detectability of such extended dust component. Given the observed properties of the galaxy, its observed continuum flux at 88 $\mu$m, $F_{88}$, depends on the dust-to-stellar mass ratio, $\xi_d$, and extent of the dust distribution, $r_d$. Once applied to the most distant galaxy known, GS-z14-0 at $z=14.32$, the fiducial model ($\xi_d = 1/529$) predicts $F_{88}^{\rm fid} = 14.9\, \mu$Jy, and a dust extent $r_d=1.4$ kpc. If the galaxy is very dust-rich ($\xi_d =1/40$), $F_{88}^{\rm max} = 40.1\, \mu$Jy. These values are smaller ($F_{88}^{\rm fid} = 9.5\, \mu$Jy) if the dust is predominantly made of large grains as those formed in SN ejecta. Forthcoming ALMA observations might come very close to constraining the fiducial predictions of the outflow-based attenuation-free model. Other super-early galaxies are predicted to be fainter at 88 $\mu$m, mostly because of their lower SFR compared to GS-z14-0, with fiducial fluxes in the range $2-5.2\ \mu$Jy.