A dusty protocluster surrounding the binary galaxy HerBS-70 at z = 2.3
Abstract
We report on deep SCUBA-2 observations at 850 $\mu$m and NOrthern Extended Millimetre Array (NOEMA) spectroscopic measurements at 2 mm of the environment surrounding the luminous, massive (M* ≈ 2 × 1011 M⊙) Herschel-selected source HerBS-70. This source was revealed by previous NOEMA observations to be a binary system of dusty star-forming galaxies at z = 2.3, with the east component (HerBS-70E) hosting an active galactic nucleus. The SCUBA-2 observations detected, in addition to the binary system, 21 sources at >3.5σ over an area of ~25 square comoving Mpc with a sensitivity of 1σ850 = 0.75 mJy. The surface density of continuum sources around HerBS-70 is three times higher than for field galaxies. The NOEMA spectroscopic measurements confirm the protocluster membership of three of the nine brightest sources through their CO(4-3) line emission, yielding a volume density 36 times higher than for field galaxies. All five confirmed sub-mm galaxies in the HerBS-70 system have relatively short gas depletion times (80-500 Myr), indicating the onset of quenching for this protocluster core due to the depletion of gas. The dark matter halo mass of the HerBS-70 system is estimated around 5 × 1013 M⊙, with a projected current-day mass of 1015 M⊙, similar to the local Virgo and Coma clusters. These observations support the claim that DSFGs, in particular the ones with observed multiplicity, can trace cosmic overdensities.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2024
- DOI:
- 10.1093/mnras/stae1155
- arXiv:
- arXiv:2404.18991
- Bibcode:
- 2024MNRAS.530.4578B
- Keywords:
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- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 19 pages, 13 figures, accepted for publication in MNRAS