Year: 2026
Type: preprint
Abstract: Galaxies with the faintest surface brightness are currently known only in the Local Group. Similar objects should exist beyond our vicinity and are crucial for understanding galaxy evolution, structure, and dark matter content, yet surveys have not reached the depth required to detect them systematically. We present a population of seven almost-dark galaxies identified in Data Preview 2 of the Rubin Legacy Survey of Space and Time. They surround M49 in the vicinity of the Virgo Cluster, and exhibit central surface brightnesses in the range of $26.9 - 28.5 \, \mathrm{mag \, arcsec^{-2}}$ in the $g$-band, with half-light radii of $0.6 - 4.6 \, \mathrm{kpc}$ at the distance of Virgo, and stellar masses of $10^6 - 10^7 \, \mathrm{M_\odot}$. Their characteristics are analogous to those of the faintest and low-mass galaxies identified among satellite galaxies And XXI, And XXIII, and And XXV in the Local Group. This discovery demonstrates the power of the forthcoming Rubin LSST 10-year survey to uncover extremely faint galaxies at scale, promising the large statistical samples needed to constrain the faint-end luminosity function and the nature of dark matter.
Source: arXiv (Cornell University)
Authors: Le, Minh Ngoc, Knapen, Johan H., Ivezić, Željko, Junais, Watkins, Aaron, Taranu, Dan S., Duc, Pierre-Alain, Englert, Anthony, Nourbakhsh, Erfan, Tyson, J. Anthony, Li, Jiaxuan, Assef, Roberto J., Aydin, Uzay, Benavides, Jose, Cardoso, Natanael M., Chakraborty, Priyanka, Demarco, Ricardo, Dullo, Bililign, Graham, Alister W., Huertas-Company, Marc, Lim, Kian-Tat, Nadolny, Jakub, Nguyen, Dieu, Peletier, Reynier, Ragusa, Rossella, Reil, Kevin, Rich, R. Michael, Hernandez-Toledo, Hector, Wilkinson, Michael H. F.
Institutions: Universidad de La Laguna, Instituto de Astrofísica de Canarias, University of Washington, Leibniz Institute for Astrophysics Potsdam, University of Hertfordshire, Princeton University, Centre National de la Recherche Scientifique, Observatoire astronomique de Strasbourg, Université de Strasbourg, Brown University, University of California, Davis, Stanford University, Universidad Diego Portales, Erciyes University, University of California, Riverside, Universidade de São Paulo, Center for Astrophysics Harvard & Smithsonian, Universidad Andrés Bello, Embry-Riddle Aeronautical University Daytona Beach Florida Campus, Embry–Riddle Aeronautical University, Swinburne University of Technology, SLAC National Accelerator Laboratory, Adam Mickiewicz University in Poznań, University of Michigan, University of Groningen, Astronomical Observatory of Capodimonte, National Institute for Astrophysics, University of California, Los Angeles, Universidad Nacional Autónoma de México
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Alexander von Humboldt-Stiftung, European Commission, Agencia Nacional de Investigación y Desarrollo, Office of Science, Science and Technology Facilities Council, European Regional Development Fund, Agencia Estatal de Investigación, SLAC National Accelerator Laboratory
Awards: G1039773812, G1058702018, G1229526393, G1458934781, G1622782223, G2371548206, G262532246, Unravelling the Dark Universe from the Canary Islands Observatories, G303061748, G3452655474, G410571670, G4235786860, G4267812785, G451917667, G4654690619, G495301720, G498139845, G5195188938, G523076202, G5539308778, G5570207115, G5622099616, G5967599077, G5987630651, G6033112984, UK involvement in LSST: Phase C (Herts component), G639391236, G6823224962, Excellence in Galaxies - Twinning the IAC, G7870178575, G8330169115, G8382000481, G8726098666, CENTRO DE ASTROFISICA Y TECNOLOGIAS AFINES (CATA), G8884978077, G8945569637, G9000451760
OpenAlex ID: W7213600465