JWST UNCOVER: Extremely Red and Compact Object at z phot ≃ 7.6 Triply Imaged by A2744
Feltre, Anna; Chevallard, Jacopo; Franx, Marijn; Glazebrook, Karl; Labbé, Ivo; van Dokkum, Pieter; Fujimoto, Seiji; Bezanson, Rachel; Price, Sedona H.; Stark, Daniel P.; Endsley, Ryan; Greene, Jenny E.; Marchesini, Danilo; Curtis-Lake, Emma; Smit, Renske; Williams, Christina C.; Suess, Katherine A.; Leja, Joel; Nelson, Erica J.; Whitaker, Katherine E.; Brammer, Gabriel B.; Zitrin, Adi; Vidal-García, Alba; Atek, Hakim; Fudamoto, Yoshinobu; Wang, Bingjie; Weaver, John R.; Dayal, Pratika; Furtak, Lukas J.; Pan, Richard; Plat, Adèle; Mowla, Lamiya A.
Israel, United States, Australia, Denmark, United Kingdom, France, Netherlands, Italy, Japan, Canada, Spain
Abstract
Recent JWST/NIRCam imaging taken for the ultra-deep UNCOVER program reveals a very red dropout object at z phot ≃ 7.6, triply imaged by the galaxy cluster A2744 (z d = 0.308). All three images are very compact, i.e., unresolved, with a delensed size upper limit of r e ≲ 35 pc. The images have apparent magnitudes of m F444W ~ 25-26 AB, and the magnification-corrected absolute UV magnitude of the source is M UV,1450 = -16.81 ± 0.09. From the sum of observed fluxes and from a spectral energy distribution (SED) analysis, we obtain estimates of the bolometric luminosities of the source of L bol ≳ 1043 erg s-1 and L bol ~ 1044-1046 erg s-1, respectively. Based on its compact, point-like appearance, its position in color-color space, and the SED analysis, we tentatively conclude that this object is a UV-faint dust-obscured quasar-like object, i.e., an active galactic nucleus at high redshift. We also discuss other alternative origins for the object's emission features, including a massive star cluster, Population III, supermassive, or dark stars, or a direct-collapse black hole. Although populations of red galaxies at similar photometric redshifts have been detected with JWST, this object is unique in that its high-redshift nature is corroborated geometrically by lensing, that it is unresolved despite being magnified-and thus intrinsically even more compact-and that it occupies notably distinct regions in both size-luminosity and color-color space. Planned UNCOVER JWST/NIRSpec observations, scheduled in Cycle 1, will enable a more detailed analysis of this object.