The ALMA-CRISTAL Survey: Spatially-resolved Star Formation Activity and Dust Content in 4 < z < 6 Star-forming Galaxies

TL;DR

This study uses combined HST, JWST, and ALMA data to analyze spatially-resolved star formation and dust in 4<z<6 galaxies, revealing the importance of ALMA in accurate property mapping and confirming the resolved star-forming main sequence at high redshift.

Contribution

It introduces a method for spatially resolving physical properties of high-redshift galaxies using multi-wavelength data, highlighting the significance of ALMA in reducing uncertainties.

Findings

No bias in global stellar mass and SFR estimates from spatially-resolved data.

ALMA data improves accuracy of dust and SFR maps.

Resolved star-forming main sequence persists at z~5.

Abstract

Using a combination of HST, JWST, and ALMA data, we perform spatially resolved spectral energy distributions (SED) fitting of fourteen 4<z<6 UV-selected main-sequence galaxies targeted by the [CII] Resolved ISM in Star-forming Galaxies with ALMA (CRISTAL) Large Program. We consistently model the emission from stars and dust in ~0.5-1kpc spatial bins to obtain maps of their physical properties. We find no offsets between the stellar masses (M*) and star formation rates (SFRs) derived from their global emission and those from adding up the values in our spatial bins, suggesting there is no bias of outshining by young stars on the derived global properties. We show that ALMA observations are important to derive robust parameter maps because they reduce the uncertainties in Ldust (hence Av and SFR). Using these maps we explore the resolved star-forming main sequence for z~5 galaxies, finding that this relation persists in typical star-forming galaxies in the early Universe. We find less obscured star formation where the M* (and SFR) surface densities are highest, typically in the central regions, contrary to the global relation between these parameters. We speculate this could be caused by feedback driving gas and dust out of these regions. However, more observations of infrared luminosities with ALMA are needed to verify this. Finally, we test empirical SFR prescriptions based on the UV+IR and [CII] line luminosity, finding they work well at the scales probed (~kpc). Our work demonstrates the usefulness of joint HST, JWST, and ALMA resolved SED modeling analyses at high redshift.