An overdensity of Lyman break galaxies around the hot dust-obscured galaxy WISE J224607.56−052634.9

¹ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
e-mail: dejene.woldeyes@mail.udp.cl
² Physics & Astronomy, University of Leicester, 1 University Road, Leicester LE1 7RH, UK
³ Institute of Astrophysics, Foundation for Research and Technology–Hellas (FORTH), Heraklion 70013, Greece
⁴ School of Sciences, European University Cyprus, Diogenes street, Engomi, 1516 Nicosia, Cyprus
⁵ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁶ SNU Astronomy Research Center (SNUARC), Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
⁷ Department of Physics, Northwestern College, 101 7th St SW, Orange City IA 51041, USA
⁸ National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100101, PR China
⁹ Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, PR China
¹⁰ University of Chinese Academy of Sciences, Beijing 100049, PR China

Received: 18 April 2023
Accepted: 28 June 2023

Abstract

We report the identification of Lyman break galaxy (LBG) candidates around the most luminous hot dust-Obscured galaxy (Hot DOG) known, WISE J224607.56−052634.9 (W2246−0526) at z = 4.601, using deep r-, i-, and z-band imaging from the Gemini Multi-Object Spectrograph South (GMOS-S). We used the surface density of LBGs to probe the megaparsec-scale environment of W2246−0526 to characterize its richness and evolutionary state. We identified LBG candidates in the vicinity of W2246−0526 using the selection criteria developed in the Subaru Deep Field and in the Subaru XMM-Newton Deep Field, slightly modified to account for the difference between the filters used, and we find 37 and 55 LBG candidates, respectively. Matching to the z-band depths of those studies, this corresponds to δ = 5.8_−1.9^+2.4 times the surface density of LBGs expected in the field. Interestingly, the Hot DOG itself, as well as a confirmed neighbor, do not satisfy either LBG selection criteria, suggesting we may be missing a large number of companion galaxies. Our analysis shows that we have mostly likely only found those with a higher than average intergalactic medium (IGM) optical depth or moderately high dust obscuration. The number density of LBG candidates is not concentrated around W2246−0526, suggesting an early evolutionary stage for the proto-cluster, that the Hot DOG may not be the most massive galaxy, or that the Hot DOG may be affecting the IGM transparency in its vicinity. The overdensity around W2246−0526 is comparable to overdensities found around other Hot DOGs and is somewhat higher than what is typically found for radio galaxies and luminous quasars at a similar redshift.