James Webb Space Telescope Feed Post

A NIRCam-dark galaxy detected with the MIRI/F1000W filter in the MIDIS/JADES Hubble Ultra Deep Field

In the top row, we show postage stamps of Cerberus in all NIRCam bands from the JADES DR2 (Eisenstein et al., 2023b). The second row shows the same stamps but convolved with a 2-pixel radius tophat filter. The third row shows incremental stacks of NIRCam filters, starting from the reddest two bands (F480M and F460M) and adding one band at a time, down to F210M. The fourth row shows similar stacks, but avoiding F460M, which presents an artifact (see main text for details). The fifth row shows stacks starting from the bluest bands (blue_stack01 including F090W and F115W) and adding the next filter in subsequent images. All postage stamps are 1"×1", with the source marked with a circle of radius 0.''2. Green circles show the PSF FWHM (including the tophat filter). Abstract: We report the discovery of Cerberus, an extremely red object detected with the MIRI Deep Imaging Survey (MIDIS) observations in the F1000W filter of the Hubble Ultra Deep Field. The object is detected at S/N~6, with F1000W~27 mag, and it is extremely faint in both the NIRCam data gathered by the JWST Advanced Deep Extragalactic Survey, JADES, with ~30.5 mag 5s upper limits in individual bands, as well as in the MIDIS F560W ultra deep data (~29 mag, 5s). Analyzing the spectral energy distribution built with individual (low S/N) optical-to-mid-infrared filters and (S/N~5) stacks, we discuss the possible nature of this red NIRCam-dark source using a battery of codes. We discard the possibility of Cerberus being a Solar System body based on the <0.016" proper motion in the 1-year apart JADES and MIDIS observations. A sub-stellar Galactic nature is deemed unlikely, given that the Cerberus' relatively flat NIRCam-to-NIRCam and very red NIRCam-to-MIRI flux ratios are not consistent with any brown dwarf model. The extragalactic nature of Cerberus offers 3 possibilities: (1) A z~0.4 galaxy with strong emission from polycyclic aromatic hydrocarbons; the very low inferred stellar mass, M?=105-6 M?, makes this possibility highly improbable. (2) A dusty galaxy at z~4 with an inferred stellar mass M?~108 M?. (3) A galaxy with observational properties similar to those of the reddest little red dots discovered around z~7, but Cerberus lying at z~15, presenting a spectral energy distribution in the rest-frame optical dominated by emission from a dusty torus or a dusty starburst.