The undiscovered ultra-diffuse galaxies of the Local Group

Abstract

Ultra-diffuse 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 $M_{\mathrm{LG}}\left(<2.5\mathrm{Mpc}\right)=8\times 10^{12}{\mathrm{M}}_{\odot }$, we predict that there are $12\pm 3$ isolated UDGs (68% confidence) with stellar masses $10^6\le M_{\ast }/{\mathrm{M}}_{\odot }<10^9,$ and effective radii $R_{\mathrm{e}}\ge 1.5\mathrm{kpc}$, 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.

arXiv comment9 pages including acknowledgements and references. Contains 5 figures and two tables. A repository of reduced data and scripts to reproduce the results in this manuscript is available at https://github.com/Musical-Neutron/lg_field_udgs and archived at https://doi.org/10.5281/zenodo.7757685 . Accepted by ApJL

References in corpus (60)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Stellar population synthesis at the resolution of 2003
• Galactic Stellar and Substellar Initial Mass Function
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Planck 2013 results. XVI. Cosmological parameters
• LSST: from Science Drivers to Reference Design and Anticipated Data Products
• E pur si muove: Galiliean-invariant cosmological hydrodynamical simulations on a moving mesh
• The observed properties of dwarf galaxies in and around the Local Group
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• Ahf: Amiga's Halo Finder
• Updated stellar yields from Asymptotic Giant Branch models
• Cosmicflows-2: The Data
• Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data
• The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time
• Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey
• Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma Cluster
• The Dark Energy Survey Data Release 1
• The evolution substructure I: a new identification method
• The Luminosity Function of the Milky Way Satellites
• ELVIS: Exploring the Local Volume in Simulations
• NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows
• Ultra-diffuse galaxies: the high-spin tail of the abundant dwarf galaxy population
• The feeble giant. Discovery of a large and diffuse Milky Way dwarf galaxy in the constellation of Crater
• (Almost) Dark Galaxies in the ALFALFA Survey: Isolated HI Bearing Ultra Diffuse Galaxies
• The origin of ultra diffuse galaxies: stellar feedback and quenching
• A kinematic study of the Andromeda dwarf spheroidal system
• The Formation of Ultra Diffuse Galaxies in Cored Dark Matter Halos Through Tidal Stripping and Heating
• The Invisibles: A Detection Algorithm to Trace the Faintest Milky Way Satellites
• Milky Way Satellite Census. I. The Observational Selection Function for Milky Way Satellites in DES Y3 and Pan-STARRS DR1
• The dynamics of isolated Local Group galaxies
• Spatial distribution of ultra-diffuse galaxies within large-scale structures
• Formation of ultra-diffuse galaxies in the field and in galaxy groups
• Galaxy Populations and Evolution in Clusters III. The Origin of Low-Mass Galaxies in Clusters: Constraints from Stellar Populations
• The total satellite population of the Milky Way
• Discovery of an ultra-diffuse galaxy in the Pisces-Perseus supercluster
• Crater 2: An Extremely Cold Dark Matter Halo
• The Hestia project: simulations of the Local Group
• The Formation of Ultra-Diffuse Galaxies in the RomulusC Galaxy Cluster Simulation
• Shadows in the Dark: Low-Surface-Brightness Galaxies Discovered in the Dark Energy Survey
• The Formation of Isolated Ultra-Diffuse Galaxies in Romulus25
• The nearest ultra diffuse galaxy: UGC2162
• A Catalog of Ultra-compact High Velocity Clouds from the ALFALFA Survey: Local Group Galaxy Candidates?
• Modeling the Connection Between Subhalos and Satellites in Milky Way-like Systems
• A tale of two populations: surviving and destroyed dwarf galaxies and the build up of the Milky Way's stellar halo
• Reconstructing cosmological initial conditions from galaxy peculiar velocities. I. Reverse Zeldovich Approximation
• Quiescent Ultra-diffuse galaxies in the field originating from backsplash orbits
• The early-type dwarf galaxy population of the Fornax cluster
• Hubble Space Telescope survey of the Perseus Cluster - I: The structure and dark matter content of cluster dwarf spheroidals
• Are Newly Discovered HI High Velocity Clouds Minihalos in the Local Group?
• Flybys, orbits, splashback: subhalos and the importance of the halo boundary
• Hubble Space Telescope Survey of the Perseus Cluster: II. Photometric scaling relations in different environments
• The sum of the masses of the Milky Way and M31: a likelihood-free inference approach
• The missing dwarf galaxies of the Local Group
• Five Gas-rich Ultra-faint Dwarf Galaxy Candidates Discovered in WIYN Imaging of ALFALFA Sources
• Local Group timing argument and virial theorem mass estimators from cosmological simulations
• The Case for Strangulation in Low-Mass Hosts: DDO 113
• Estimation of the masses in the Local Group by Gradient Boosted Decision Trees
• Metallicity profiles of Ultra Diffuse Galaxies in NIHAO simulations
• HIPASS study of southern ultradiffuse galaxies and low surface brightness galaxies

Cited by in corpus (4)

• Apocalypse When? No Certainty of a Milky Way -- Andromeda Collision
• Formation of Transitional cE/UCD Galaxies through Massive/Dwarf Disc Galaxy Mergers
• The formation and disruption of globular cluster populations in simulations of present-day $L^{\ast }$ galaxies with controlled assembly histories
• The Type Ia Supernova 2021hem: A 2003fg-like Event in an Apparently Hostless Environment