Compact, and Dust-obscured Candidate <i>z</i> 8 Galaxies Discovered by JWST Two Massive

Abstract We present a search for extremely red, dust-obscured, z > 7 galaxies with JWST/NIRCam+MIRI imaging over the first 20 arcmin2 of publicly available Cycle 1 data from the COSMOS-Web, CEERS, and PRIMER surveys. Based on their red color in F277WF444W (2.5 mag) and detection in MIRI/F770W (25 mag), we identify two galaxies, COS-z8M1 and CEERS-z7M1, that have best-fit photometric redshifts of z = 8.4 0.4 + 0.3 and 7.6 0.1 + 0.1 , respectively. We perform spectral energy distribution fitting with a variety of codes (including bagpipes, prospector, beagle, and cigale) and find a >95% probability that these indeed lie at z > 7. Both sources are compact (R eff 200 pc) and highly obscured (A V 1.52.5) and, at our best-fit redshift estimates, likely have strong [O iii]+H emission contributing to their 4.4 m photometry. We estimate stellar masses of 1010 M for both sources; by virtue of detection in MIRI at 7.7 m, these measurements are robust to the inclusion of bright emission lines, for example, from an active galactic nucleus. We identify a marginal (2.9) Atacama Large Millimeter/submillimeter Array detection at 2 mm within 0.5 of COS-z8M1, which, if real, would suggest a remarkably high IR luminosity of 1012 L . These two galaxies, if confirmed at z 8, would be extreme in their stellar and dust masses and may be representative of a substantial population of highly dust-obscured galaxies at cosmic dawn.

Akins, H. B., Casey, C. M., Allen, N., Bagley, M. B., Dickinson, M., Finkelstein, S. L., ... Zavala, J.

Akins, Hollis B||Casey, Caitlin M||Allen, Natalie||Bagley, Micaela B||Dickinson, Mark||Finkelstein, Steven L||Franco, Maximilien||Harish, Santosh||Haro, Pablo Arrabal||Ilbert, Olivier||Kartaltepe, Jeyhan S||Koekemoer, Anton M||Liu, Daizhong||Long, Arianna S||McCracken, Henry Joy||Paquereau, Louise||Papovich, Casey||Pirzkal, Nor||Rhodes, Jason||Robertson, Brant E||Shuntov, Marko||Toft, Sune||Yang, Guang||Barro, Guillermo||Bisigello, Laura||Buat, Veronique||Champagne, Jaclyn B||Cooper, Olivia||Costantin, Luca||de la Vega, Alexander||Drakos, Nicole E||Faisst, Andreas||Fontana, Adriano||Fujimoto, Seiji||Gillman, Steven||Gomez-Guijarro, Carlos||Gozaliasl, Ghassem||Hathi, Nimish P||Hayward, Christopher C||Hirschmann, Michaela||Holwerda, Benne W||Jin, Shuowen||Kocevski, Dale D||Kokorev, Vasily||Lambrides, Erini||Lucas, Ray A||Magdis, Georgios E||Magnelli, Benjamin||McKinney, Jed||Mobasher, Bahram||Perez-Gonzalez, Pablo G||Rich, R Michael||Seille, Lise-Marie||Talia, Margherita||Urry, C Megan||Valentino, Francesco||Whitaker, Katherine E||Yung, LY Aaron||Zavala, Jorge

Two Massive, Compact, and Dust-obscured Candidate z 8 Galaxies Discovered by JWST Academic Article