Abstract Details
| Name: PRALAY BISWAS Affiliation: National Centre for Radio Astrophysics Conference ID: ASI2025_681 Title : Identification and study of the Optically invisible galaxy population with JWST Authors and Co-Authors : Pralay Biswas 1, Rashi Jain 1, Yogesh Wadadekar 1 Abstract Type : Oral Abstract Category : Galaxies and Cosmology Abstract : At z > 3, the Hubble Space Telescope (HST) struggles to capture the rest-frame optical light from galaxies, limiting our comprehension of star-forming galaxies in this epoch. As a result, much of our knowledge relies on rest-frame ultraviolet observations, leaving us in the dark about certain galaxy populations—specifically, the UV-faint, dust-obscured, and quiescent galaxies. These elusive entities, referred to as HST-dark or HST-faint galaxies, have previously been identified through Spitzer/IRAC or ALMA submillimeter observations, but their precise redshifts and spectral energy distributions (SEDs) remain uncertain due to insufficient photometric data. For a complete understanding of the early galaxy evolution processes, detection and study of the physical properties of HST-dark galaxies are necessary. Using recent JWST wide and medium band NIRCam photometry from 0.6 to 5 μm, we can now obtain unprecedentedly reliable redshift and SED properties. We simultaneously estimated redshift and SED properties of around 22000 galaxies from the JWST UNCOVER survey using Bayesian Analysis of Galaxies for Physical Inference and Parameter EStimation (BAGPIPES). Applying a colour cut of F160W–F444W > 2.0 and restricting the sample to F160W > 27, we identify around 100 HST-dark galaxies. As expected, these colour-selected HST-dark galaxies are dusty with 25% having strong dust attenuation, AV > 2. The UVJ diagram commonly used to classify dusty and quiescent galaxies also corroborates that. Previous studies of HST-dark galaxies show that these galaxies are massive with moderate SFRs. However, our sensitive JWST data show that HST-dark galaxies could be less massive with a low star formation rate. Apart from very few quiescent HST-dark galaxies, they largely follow the star-forming main sequence. Our analysis shows that dusty galaxies at z > 3 are more numerous than previously thought and provide crucial information about the lower mass galaxies missed previously due to the limited sensitivity of high redshift surveys. |