Not-so-little Red Dots: Two Massive and Dusty Starbursts at z ∼ 5–7 Pushing the Limits of Star Formation Discovered by JWST in the COSMOS-Web Survey
Casey, Caitlin M.; Kartaltepe, Jeyhan S.; Koekemoer, Anton M.; Long, Arianna S.; Rhodes, Jason; Ilbert, Olivier; Robertson, Brant E.; McKinney, Jed; Toft, Sune; Hirschmann, Michaela; Liu, Daizhong; Magdis, Georgios; Kokorev, Vasily; Rich, Michael R.; Shuntov, Marko; Allen, Natalie; Franco, Maximilien; Drakos, Nicole E.; McCracken, Henry Joy; Akins, Hollis B.; Cooper, Olivia R.; Gozaliasl, Ghassem; Harish, Santosh; Paquereau, Louise; Talia, Margherita; Gentile, Fabrizio; Berman, Edward
Italy, United States, Switzerland, Denmark, Netherlands, France, China, Finland
Abstract
We present the properties of two candidate massive (M ⋆ ∼ 1011 M ⊙) and dusty (A v > 2.5 mag) galaxies at z = 5–7 in the first 0.28 deg2 of the COSMOS-Web survey. One object is spectroscopically confirmed at z spec = 5.051, while the other has a robust z phot = 6.7 ± 0.3. Thanks to their extremely red colors (F277W–F444W ∼ 1.7 mag), these galaxies satisfy the nominal color selection for the widely studied "little red dot" (LRD) population with the exception of their spatially resolved morphologies. The morphology of our targets allows us to conclude that their red continuum is dominated by highly obscured stellar emission and not by reddened nuclear activity. Using a variety of spectral energy distribution fitting tools and star formation histories, we estimate the stellar masses to be