MAGAZ3NE: Massive, Extremely Dusty Galaxies at $zsim2$ Lead to Photometric Overestimation of Number Densities of the Most Massive Galaxies at $33$, one is a $zsim1.2$ dusty galaxy, and four galaxies do not have a confirmed spectroscopic redshift. In fact, none of the sample has |$z_{rm spec}-z_{rm phot}$|$arXiv:2404.19018v1 Announce Type: new
Abstract: We present rest-frame optical spectra from Keck/MOSFIRE and Keck/NIRES of 16 candidate ultramassive galaxies targeted as part of the Massive Ancient Galaxies at $z>3$ Near-Infrared (MAGAZ3NE) Survey. These candidates were selected to have photometric redshifts $3lesssim z_{rm phot}11.7$, and well-sampled photometric spectral energy distributions (SEDs) from the UltraVISTA and VIDEO surveys. In contrast to previous spectroscopic observations of blue star-forming and post-starburst ultramassive galaxies, candidates in this sample have very red SEDs implying significant dust attenuation, old stellar ages, and/or active galactic nuclei (AGN). Of these galaxies, eight are revealed to be heavily dust-obscured $2.03$, one is a $zsim1.2$ dusty galaxy, and four galaxies do not have a confirmed spectroscopic redshift. In fact, none of the sample has |$z_{rm spec}-z_{rm phot}$|$