The Undiscovered Ultradiffuse Galaxies of the Local Group

Newton, Oliver and Di Cintio, Arianna and Cardona–Barrero, Salvador and Libeskind, Noam I. and Hoffman, Yehuda and Knebe, Alexander and Sorce, Jenny G. and Steinmetz, Matthias and Tempel, Elmo (2023) The Undiscovered Ultradiffuse Galaxies of the Local Group. The Astrophysical Journal Letters, 946 (2). L37. ISSN 2041-8205

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Ultradiffuse galaxies (UDGs) are attractive candidates to probe cosmological models and test theories of galaxy formation at low masses; however, they are difficult to detect because of their low surface brightness. In the Local Group a handful of UDGs have been found to date, most of which are satellites of the Milky Way and M31, and only two are isolated galaxies. It is unclear whether so few UDGs are expected. We address this by studying the population of UDGs formed in hydrodynamic constrained simulations of the Local Group from the HESTIA suite. For a Local Group with a total enclosed mass MLG( < 2.5 Mpc) = 8 × 1012 M⊙, we predict that there are 12 ± 3 isolated UDGs (68% confidence) with stellar masses 106 ≤ M*/M⊙ < 109, and effective radii Re ≥ 1.5 kpc, within 2.5 Mpc of the Local Group, of which ${2}_{-1}^{+2}$ (68% confidence) are detectable in the footprint of the Sloan Digital Sky Survey (SDSS). Accounting for survey incompleteness, we find that almost the entire population of UDGs in the Local Group field would be observable in a future all-sky survey with a depth similar to the SDSS, the Dark Energy Survey, or the Legacy Survey of Space and Time. Our results suggest that there is a population of UDGs in the Local Group awaiting discovery.

Item Type: Article
Subjects: Eprints STM archive > Physics and Astronomy
Depositing User: Unnamed user with email admin@eprints.stmarchive
Date Deposited: 27 Apr 2023 07:57
Last Modified: 19 Sep 2023 07:43

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