Rubin LSST DP2 unveils almost-dark galaxies in the Virgo Cluster
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 mag arcsec−2 in the g-band, with half-light radii of 0.6 − 4.6 kpc at the distance of Virgo, and stellar masses of 106 − 107 M⊙. 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.
Related
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BibTeX
@misc{le2026rubin,
title = {{Rubin LSST DP2 unveils almost-dark galaxies in the Virgo Cluster}},
author = {Minh Ngoc Le and Johan H. Knapen and Željko Ivezić and Junais and Aaron Watkins and Dan S. Taranu and Pierre-Alain Duc and Anthony Englert and Erfan Nourbakhsh and J. Anthony Tyson and Jiaxuan Li and Roberto J. Assef and Uzay Aydin and Jose Benavides and Natanael M. Cardoso and Priyanka Chakraborty and Ricardo Demarco and Bililign Dullo and Alister W. Graham and Marc Huertas-Company and Kian-Tat Lim and Jakub Nadolny and Dieu Nguyen and Reynier Peletier and Rossella Ragusa and Kevin Reil and R. Michael Rich and Hector Hernandez-Toledo and Michael H. F. Wilkinson},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.19246},
eprint = {2609.19246},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.19246},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Rubin LSST DP2 unveils almost-dark galaxies in the Virgo Cluster
AU - Minh Ngoc Le
AU - Johan H. Knapen
AU - Željko Ivezić
AU - Junais
AU - Aaron Watkins
AU - Dan S. Taranu
AU - Pierre-Alain Duc
AU - Anthony Englert
AU - Erfan Nourbakhsh
AU - J. Anthony Tyson
AU - Jiaxuan Li
AU - Roberto J. Assef
AU - Uzay Aydin
AU - Jose Benavides
AU - Natanael M. Cardoso
AU - Priyanka Chakraborty
AU - Ricardo Demarco
AU - Bililign Dullo
AU - Alister W. Graham
AU - Marc Huertas-Company
AU - Kian-Tat Lim
AU - Jakub Nadolny
AU - Dieu Nguyen
AU - Reynier Peletier
AU - Rossella Ragusa
AU - Kevin Reil
AU - R. Michael Rich
AU - Hector Hernandez-Toledo
AU - Michael H. F. Wilkinson
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2609.19246
UR - https://arxiv.org/abs/2609.19246
AB - 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 mag arcsec^−2 in the g-band, with half-light radii of 0.6 − 4.6 kpc at the distance of Virgo, and stellar masses of 10^6 − 10^7 M_⊙. 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.
ER -