2024/09/17 by N.E.P. Lines, R. A. A. Bowler, Lines, N. E. P. +59 · 2 citations
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2409.10963
openalex publication_date 2024/09/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a spatially resolved analysis of four star-forming galaxies at z = 4.44-5.64 using data from the JWST PRIMER and ALMA-CRISTAL surveys to probe the stellar and inter-stellar medium properties on the sub-kpc scale. In the 1-5 μ\rm m JWST NIRCam imaging we find that the galaxies are composed of multiple clumps (between 2 and ∼ 8) separated by ≃ 5 \rm kpc, with comparable morphologies and sizes in the rest-frame UV and optical. Using BAGPIPES to perform pixel-by-pixel SED fitting to the JWST data we show that the SFR (≃ 25 \rm M\odot/\rm yr) and stellar mass (\rm log10(M⋆/\rm M\odot) ≃ 9.5) derived from the resolved analysis are in close ( \lesssim 0.3 \rm dex) agreement with those obtained by fitting the integrated photometry. In contrast to studies of lower-mass sources, we thus find a reduced impact of outshining of the older (more massive) stellar populations in these normal z ≃ 5 galaxies. Our JWST analysis recovers bluer rest-frame UV slopes (β≃ -2.1) and younger ages (≃ 100 \rm Myr) than archival values. We find that the dust continuum from ALMA-CRISTAL seen in two of these galaxies correlates, as expected, with regions of redder rest-frame UV slopes and the SED-derived A\rm V, as well as the peak in the stellar mass map. We compute the resolved IRX-β relation, showing that the IRX is consistent with the local starburst attenuation curve and further demonstrating the presence of an inhomogeneous dust distribution within the galaxies. A comparison of the CRISTAL sources to those from the FirstLight zoom-in simulation of galaxies with the same M⋆ and SFR reveals similar age and colour gradients, suggesting that major mergers may be important in the formation of clumpy galaxies at this epoch.