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 center of the figure, we show an RGB composition of the MIDIS F1000W field. The color images have been built with JADES data in 2 NIRCam filters, F277W and F356W, and the MIDIS MIRI F1000W filter (all images convolved to the same PSF of MIRI/F1000W). In the background, we show the HUDF JADES data in grayscale. We provide a series of zoomed-in RGB frames that lead to the NIRCam-dark MIRI source, Cerberus, whose image is located at the bottom right corner. The NIRCam-dark MIRI source Cerberus is highlighted with a square in that RGB frame. Additionally, we provide postage stamp images (2"×2") of Cerberus in MIRI/F1000W, MIRI/F560W, and NIRCam/F444W (left column), showcasing that Cerberus (marked with an r=0.''25 green circle) is clearly detected only at 10 um. 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.