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Cold, substellar objects such as brown dwarfs have long been recognized ascontaminants in color-selected samples of active galactic nuclei (AGNs). Inparticular, their near- to mid-infrared colors (1-5 $\mu$m) can closelyresemble the V-shaped ($f_{\lambda}$) spectra of highly-reddened accretingsupermassive black holes ("little red dots"), especially at $6 < z < 7$.Recently, a NIRCam-selected sample of little red dots over 45 arcmin$^2$ hasbeen followed up with deep NIRSpec multi-object prism spectroscopy through theUNCOVER program. By investigating the acquired spectra, we identify three ofthe 14 followed-up objects as T/Y dwarfs with temperatures between 650 and 1300K and distances between 0.8 and 4.8 kpc. At $4.8^{+0.6}_{-0.1}$ kpc,Abell2744-BD1 is the most distant brown dwarf discovered to date. We identifythe remaining 11 objects as extragalactic sources at $z_{\rm spec} \gtrsim 5$.Given that three of these sources are strongly-lensed images of the same AGN(Abell2744-QSO1), we derive a brown dwarf contamination fraction of $25\%$ inthis NIRCam-selection of little red dots. We find that in the near-infraredfilters, brown dwarfs appear much bluer than the highly-reddened AGN, providingan avenue for distinguishing the two and compiling cleaner samples ofphotometrically selected highly-reddened AGN.

Little Red Dots or Brown Dwarfs? NIRSpec Discovery of Three Distant Brown Dwarfs Masquerading as NIRCam-Selected Highly-Reddened AGNs