The Astrophysical Journal (Jan 2025)
A Pride of Satellites in the Constellation Leo? Discovery of the Leo VI Milky Way Satellite Ultra-faint Dwarf Galaxy with DELVE Early Data Release 3
- C. Y. Tan,
- W. Cerny,
- A. Drlica-Wagner,
- A. B. Pace,
- M. Geha,
- A. P. Ji,
- T. S. Li,
- M. Adamów,
- D. Anbajagane,
- C. R. Bom,
- J. A. Carballo-Bello,
- J. L. Carlin,
- C. Chang,
- A. Chaturvedi,
- A. Chiti,
- Y. Choi,
- M. L. M. Collins,
- A. Doliva-Dolinsky,
- P. S. Ferguson,
- R. A. Gruendl,
- D. J. James,
- G. Limberg,
- M. Navabi,
- D. Martínez-Delgado,
- C. E. Martínez-Vázquez,
- G. E. Medina,
- B. Mutlu-Pakdil,
- D. L. Nidever,
- N. E. D. Noël,
- A. H. Riley,
- J. D. Sakowska,
- D. J. Sand,
- J. Sharp,
- G. S. Stringfellow,
- C. Tolley,
- D. L. Tucker,
- A. K. Vivas,
- (DELVE Collaboration)
Affiliations
- C. Y. Tan
- ORCiD
- Kavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USA ; [email protected]; Department of Physics, University of Chicago , Chicago, IL 60637, USA
- W. Cerny
- ORCiD
- Department of Astronomy, Yale University , New Haven, CT 06520, USA
- A. Drlica-Wagner
- ORCiD
- Kavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USA ; [email protected]; Fermi National Accelerator Laboratory , P.O. Box 500, Batavia, IL 60510, USA; Department of Astronomy and Astrophysics, University of Chicago , Chicago, IL 60637, USA
- A. B. Pace
- ORCiD
- McWilliams Center for Cosmology & Astrophysics, Carnegie Mellon University , 5000 Forbes Ave, Pittsburgh, PA 15213, USA
- M. Geha
- ORCiD
- Department of Astronomy, Yale University , New Haven, CT 06520, USA
- A. P. Ji
- ORCiD
- Kavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USA ; [email protected]; Department of Astronomy and Astrophysics, University of Chicago , Chicago, IL 60637, USA
- T. S. Li
- ORCiD
- Department of Astronomy and Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada
- M. Adamów
- ORCiD
- Center for Astrophysical Surveys , National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA
- D. Anbajagane
- ORCiD
- Kavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USA ; [email protected]; Department of Astronomy and Astrophysics, University of Chicago , Chicago, IL 60637, USA
- C. R. Bom
- ORCiD
- Centro Brasileiro de Pesquisas Físicas , Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ, Brazil
- J. A. Carballo-Bello
- ORCiD
- Instituto de Alta Investigación, Universidad de Tarapacá , Casilla 7D, Arica, Chile
- J. L. Carlin
- ORCiD
- Rubin Observatory/AURA , 950 North Cherry Avenue, Tucson, AZ 85719, USA
- C. Chang
- ORCiD
- Kavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USA ; [email protected]; Department of Astronomy and Astrophysics, University of Chicago , Chicago, IL 60637, USA
- A. Chaturvedi
- ORCiD
- Department of Physics, University of Surrey , Guildford, GU2 7XH, UK
- A. Chiti
- ORCiD
- Kavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USA ; [email protected]; Department of Astronomy and Astrophysics, University of Chicago , Chicago, IL 60637, USA
- Y. Choi
- ORCiD
- NSF NOIRLab , 950 N. Cherry Ave., Tucson, AZ 85719, USA
- M. L. M. Collins
- ORCiD
- Department of Physics, University of Surrey , Guildford, GU2 7XH, UK
- A. Doliva-Dolinsky
- ORCiD
- Department of Chemistry and Physics, University of Tampa , 401 West Kennedy Boulevard, Tampa, FL 33606, USA; Department of Physics and Astronomy, Dartmouth College , Hanover, NH 03755, USA
- P. S. Ferguson
- ORCiD
- Department of Physics, University of Wisconsin-Madison , Madison, WI 53706, USA
- R. A. Gruendl
- ORCiD
- Center for Astrophysical Surveys , National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA; Department of Astronomy, University of Illinois , 1002 W. Green Street, Urbana, IL 61801, USA
- D. J. James
- ORCiD
- ASTRAVEO LLC , PO Box 1668, Gloucester, MA 01931, USA; Applied Materials Inc. , 35 Dory Road, Gloucester, MA 01930, USA
- G. Limberg
- ORCiD
- Kavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USA ; [email protected]; Universidade de São Paulo , IAG, Departamento de Astronomia, SP 05508-090, São Paulo, Brazil
- M. Navabi
- ORCiD
- Department of Physics, University of Surrey , Guildford, GU2 7XH, UK
- D. Martínez-Delgado
- ORCiD
- Instituto de Astrofísica de Andalucía , CSIC, E-18080 Granada, Spain
- C. E. Martínez-Vázquez
- ORCiD
- International Gemini Observatory/NSF NOIRLab , 670 N. A’ohoku Place, Hilo, HI 96720, USA
- G. E. Medina
- ORCiD
- Department of Astronomy and Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada
- B. Mutlu-Pakdil
- ORCiD
- Department of Physics and Astronomy, Dartmouth College , Hanover, NH 03755, USA
- D. L. Nidever
- ORCiD
- NSF NOIRLab , 950 N. Cherry Ave., Tucson, AZ 85719, USA; Department of Physics, Montana State University , P.O. Box 173840, Bozeman, MT 59717-3840, USA
- N. E. D. Noël
- ORCiD
- Department of Physics, University of Surrey , Guildford, GU2 7XH, UK
- A. H. Riley
- ORCiD
- Institute for Computational Cosmology, Department of Physics, Durham University , South Road, Durham, DH1 3LE, UK
- J. D. Sakowska
- ORCiD
- Department of Physics, University of Surrey , Guildford, GU2 7XH, UK
- D. J. Sand
- ORCiD
- Department of Astronomy, Steward Observatory , 933 North Cherry Avenue, Room N204, Tucson, AZ 85721-0065, USA
- J. Sharp
- ORCiD
- Department of Astronomy and Astrophysics, University of Chicago , Chicago, IL 60637, USA
- G. S. Stringfellow
- ORCiD
- Center for Astrophysics and Space Astronomy, University of Colorado , 389 UCB, Boulder, CO 80309-0389, USA
- C. Tolley
- ORCiD
- Department of Astronomy, University of California , Berkeley, CA 94720-3411, USA
- D. L. Tucker
- ORCiD
- Fermi National Accelerator Laboratory , P.O. Box 500, Batavia, IL 60510, USA
- A. K. Vivas
- ORCiD
- Cerro Tololo Inter-American Observatory, NSF NOIRLab , Casilla 603, La Serena, Chile
- (DELVE Collaboration)
- DOI
- https://doi.org/10.3847/1538-4357/ad9b0c
- Journal volume & issue
-
Vol. 979,
no. 2
p. 176
Abstract
We report the discovery and spectroscopic confirmation of an ultra-faint Milky Way satellite in the constellation of Leo. This system was discovered as a spatial overdensity of resolved stars observed with Dark Energy Camera (DECam) data from an early version of the third data release of the DECam Local Volume Exploration (or DELVE) survey. The low luminosity ( ${M}_{V}=-3.5{6}_{-0.37}^{+0.47}$ ; ${L}_{V}=230{0}_{-700}^{+1200}{L}_{\odot }$ ), large size ( ${R}_{1/2}=9{0}_{-30}^{+30}$ pc), and large heliocentric distance ( $D=11{1}_{-6}^{+9}$ kpc) are all consistent with the population of ultra-faint dwarf galaxies (UFDs). Using Keck/DEIMOS observations of the system, we were able to spectroscopically confirm nine member stars, while measuring a tentative mass-to-light ratio of $70{0}_{-500}^{+1400}{M}_{\odot }/{L}_{\odot }$ and a nonzero metallicity dispersion of ${\sigma }_{[\mathrm{Fe}/{\rm{H}}]}=0.1{9}_{-0.11}^{+0.14}$ , further confirming Leo VI’s identity as a UFD. While the system has a highly elliptical shape, $\epsilon =0.5{4}_{-0.29}^{+0.19}$ , we do not find any conclusive evidence that it is tidally disrupting. Moreover, despite the apparent on-sky proximity of Leo VI to members of the proposed Crater-Leo infall group, its smaller heliocentric distance and inconsistent position in energy–angular momentum space make it unlikely that Leo VI is part of the proposed infall group.
Keywords
