JADES: Resolving the Stellar Component and Filamentary Overdense Environment of Hubble Space Telescope (HST)-dark Submillimeter Galaxy HDF850.1 at z = 5.18
Chevallard, Jacopo; Übler, Hannah; Bunker, Andrew J.; Maiolino, Roberto; Willott, Chris; Johnson, Benjamin D.; Ji, Zhiyuan; Shivaei, Irene; Chen, Zuyi; Lyu, Jianwei; Rieke, George H.; Curtis-Lake, Emma; Witstok, Joris; Charlot, Stephane; Alberts, Stacey; Egami, Eiichi; Eisenstein, Daniel J.; Sun, Fengwu; Tacchella, Sandro; Willmer, Christopher N. A.; Baker, William M.; Bhatawdekar, Rachana; Boyett, Kristan; Helton, Jakob M.; Sandles, Lester; Hainline, Kevin N.; Rieke, Marcia J.; Rujopakarn, Wiphu; Robertson, Brant; Danhaive, A. Lola; DeCoursey, Christa
United States, United Kingdom, Spain, Netherlands, Australia, France, Thailand, Canada
Abstract
HDF850.1 is the brightest submillimeter galaxy (SMG) in the Hubble Deep Field. It is known as a heavily dust-obscured star-forming galaxy embedded in an overdense environment at z = 5.18. With nine-band NIRCam images at 0.8-5.0 μm obtained through the JWST Advanced Deep Extragalactic Survey, we detect and resolve the rest-frame UV-optical counterpart of HDF850.1, which splits into two components because of heavy dust obscuration in the center. The southern component leaks UV and Hα photons, bringing the galaxy ~100 times above the empirical relation between infrared excess and UV continuum slope (IRX-β UV). The northern component is higher in dust attenuation and thus fainter in UV and Hα surface brightness. We construct a spatially resolved dust-attenuation map from the NIRCam images, well matched with the dust continuum emission obtained through millimeter interferometry. The whole system hosts a stellar mass of 1010.8±0.1 M ⊙ and star formation rate (SFR) of 102.8±0.2 M ⊙ yr-1, placing the galaxy at the massive end of the star-forming main sequence at this epoch. We further confirm that HDF850.1 resides in a complex overdense environment at z = 5.17-5.30, which hosts another luminous SMG at z = 5.30 (GN10). The filamentary structures of the overdensity are characterized by 109 Hα-emitting galaxies confirmed through NIRCam slitless spectroscopy at 3.9-5 μm, of which only eight were known before the JWST observations. Given the existence of a similar galaxy overdensity in the GOODS-S field, our results suggest that 50% ± 20% of the cosmic star formation at z = 5.1-5.5 occur in protocluster environments.