A Deep Look at the Ultra-Faint Milky Way Satellite Virgo III with Rubin Observatory Data Preview 2

[2607.25044] A Deep Look at the Ultra-Faint Milky Way Satellite Virgo III with Rubin Observatory Data Preview 2 Skip to main content Search Submit Donate Log in Search arXiv Press Enter to search · Advanced search Astrophysics > Astrophysics of Galaxies arXiv:2607.25044 (astro-ph) [Submitted on 27 Jul 2026 ( v1 ), last revised 14 Aug 2026 (this version, v2)] Title: A Deep Look at the Ultra-Faint Milky Way Satellite Virgo III with Rubin Observatory Data Preview 2 Authors: Aashay Pai , Alex Drlica-Wagner , Peter S. Ferguson , William Cerny , Chin Yi Tan , Jeffrey L. Carlin , Yumi Choi , Željko Ivezić , Lauren A. MacArthur , Colin T. Slater , Dan S. Taranu , Brian Yanny View a PDF of the paper titled A Deep Look at the Ultra-Faint Milky Way Satellite Virgo III with Rubin Observatory Data Preview 2, by Aashay Pai and 11 other authors View PDF HTML (experimental) Abstract: We analyze the ultra-faint Milky Way satellite Virgo III using data from the Vera C. Rubin Observatory Data Preview 2 (DP2). Virgo III was observed in the Rubin "Cosmic Treasure Chest" (M49) First Look field, which contains 924 visits in the u,g,r,i bands comprising ~10.5hrs of exposure time with LSSTCam. These data are considerably deeper than the majority of DP2, with a $5\sigma$ limiting magnitude that approaches the expected 10-year depth of LSST (~25.2-26.5mag, depending on band). We report the morphological and stellar population parameters of Virgo III measured with the maximum-likelihood-based package ugali. The depth of the Rubin imaging yields more than a factor of four increase in the number of candidate member stars ($N_* = 114^{+11}_{-11}$) relative to the Virgo III discovery results ($N_* = 25^{+5}_{-4}$), enabling significantly more precise morphological constraints. Our best-fit parameters broadly agree with previous measurements, further confirming that Virgo III has properties that are consistent with an ultra-faint dwarf galaxy ($M_V = -2.72^{+0.49}_{-0.70}$; $r_{1/2} = 53^{+10}_{-8}$) located at a heliocentric distance of $D_\odot = 151^{+8}_{-8}$. We also demonstrate that the depth and photometric quality of the DP2 data are sufficient to separate metal-poor and metal-rich stars in color-color space. We further present period estimates for the three known RR Lyrae member stars derived from the DP2 forced photometry; we use theoretical Period-Luminosity-Metallicity (PLZ) and Period-Wesenheit-Metallicity (PWZ) relations to obtain independent distance estimates. We find that our period and distance estimates are broadly consistent with previous measurements for these RR Lyrae. These results demonstrate the power of LSST data for the discovery and characterization of ultra-faint dwarf galaxies and motivate future searches for new satellites across the southern sky. Comments: 21 pages, 14 figures Subjects: Astrophysics of Galaxies (astro-ph.GA) Report number: FERMILAB-PUB-26-0487-PPD Cite as: arXiv:2607.25044 [astro-ph.GA] (or arXiv:2607.25044v2 [astro-ph.GA] for this version) https://doi.org/10.48550/arXiv.2607.25044 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Aashay Pai [ view email ] [v1] Mon, 27 Jul 2026 20:06:01 UTC (11,981 KB) [v2] Fri, 14 Aug 2026 19:56:58 UTC (11,693 KB) Full-text links: Access Paper: View a PDF of the paper titled A Deep Look at the Ultra-Faint Milky Way Satellite Virgo III with Rubin Observatory Data Preview 2, by Aashay Pai and 11 other authors View PDF HTML (experimental) TeX Source view license Current browse context: astro-ph.GA < prev | next > new | recent | 2026-07 Change to browse by: astro-ph References & Citations NASA ADS Google Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... 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