Eridanus IV: an Ultra-faint Dwarf Galaxy Candidate Discovered in the DECam Local Volume Exploration Survey

Journal Article · Mon Oct 25 00:00:00 EDT 2021 · Astrophys.J.Lett.

DOI:https://doi.org/10.3847/2041-8213/ac2d9a· OSTI ID:1824804

Cerny, W. ^[1]; Pace, A. B. ^[2]; Drlica-Wagner, A. ^[3]; Koposov, S. E. ^[4]; Vivas, A. K. ^[5]; Mau, S. ^[6]; Riley, A. H. ^[7]; Bom, C. R. ^[8]; Carlin, J. L. ^[9]; Choi, Y. ^[10]; Erkal, D. ^[11]; Ferguson, P. S. ^[7]; James, D. J. ^[12]; Li, T. S. ^[13]; Martínez-Delgado, D. ^[14]; Martínez-Vázquez, C. E. ^[5]; Munoz, R. R. ^[15]; Mutlu-Pakdil, B. ^[1]; Olsen, K.A. G. ^[16]; Pieres, A. ^[17] ; Sakowska, J. D. ^[11]; Sand, D. J. ^[18]; Simon, J. D. ^[19]; Smercina, A. ^[20]; Stringfellow, G. S. ^[21]; Tollerud, E. J. ^[10]; Adamów, M. ^[22]; Hernandez-Lang, D. ^[23]; Kuropatkin, N. ^[24]; Santana-Silva, L. ^[25]; Tucker, D. L. ^[24]; Zenteno, A. ^[5]

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1. Chicago U., KICP; Chicago U., Astron. Astrophys. Ctr.
2. Carnegie Mellon U.
3. Fermilab; Chicago U., KICP; Chicago U., Astron. Astrophys. Ctr.
4. Edinburgh U., Inst. Astron.; Cambridge U., Inst. of Astron.; Cambridge U., KICC
5. Cerro-Tololo InterAmerican Obs.
6. Stanford U.; KIPAC, Menlo Park
7. Texas A-M
8. Rio de Janeiro, CBPF
9. LSST, Tucson; Rubin Observ.
10. Baltimore, Space Telescope Sci.
11. Surrey U.
12. Harvard-Smithsonian Ctr. Astrophys.; Unlisted, UK
13. Carnegie Inst. Observ.; Princeton U.
14. IAA, Granada
15. Millenium Inst. Astro., Santiago
16. LSST Corp.
17. LIneA, Rio de Janeiro; Rio de Janeiro Observ.
18. Arizona U., Astron. Dept. - Steward Observ.
19. Carnegie Inst. Observ.
20. Washington U., Seattle, Astron. Dept.
21. Colorado U., CASA
22. NCSA, Urbana
23. Munich U.
24. Fermilab
25. Cruzeiro do Sul U.; UNICID, Sao Paulo

We present the discovery of a candidate ultra-faint Milky-Way satellite, Eridanus IV (DELVE J0505−0931), detected in photometric data from the DECam Local Volume Exploration survey (DELVE). Eridanus IV is a faint (M V = − 4.7 ± 0.2), extended (), and elliptical (ϵ = 0.54 ± 0.1) system at a heliocentric distance of , with a stellar population that is well described by an old, metal-poor isochrone (age of τ ∼ 13.0 Gyr and metallicity of [Fe/H] ≲ − 2.1 dex). These properties are consistent with the known population of ultra-faint Milky-Way satellite galaxies. Eridanus IV is also prominently detected using proper-motion measurements from Gaia Early Data Release 3, with a systemic proper motion of mas yr−1 measured from its horizontal branch and red-giant-branch member stars. We find that the spatial distribution of likely member stars hints at the possibility that the system is undergoing tidal disruption.

• Research Organization: Arizona U., Astron. Dept. - Steward Observ.; Baltimore, Space Telescope Sci.; Cambridge U., Inst. of Astron.; Cambridge U., KICC; Carnegie Inst. Observ.; Carnegie Mellon U.; Cerro-Tololo InterAmerican Obs.; Chicago U., Astron. Astrophys. Ctr.; Chicago U., KICP; Colorado U., CASA; Cruzeiro do Sul U.; Edinburgh U., Inst. Astron.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Harvard-Smithsonian Ctr. Astrophys.; IAA, Granada; LIneA, Rio de Janeiro; LSST Corp.; LSST, Tucson; Millenium Inst. Astro., Santiago; Munich U.; NCSA, Urbana; Princeton U.; Rio de Janeiro Observ.; Rio de Janeiro, CBPF; Rubin Observ.; SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford U.; Surrey U.; Texas A-M; UNICID, Sao Paulo; Unlisted, UK; Washington U., Seattle, Astron. Dept.
• Sponsoring Organization: US Department of Energy
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1824804
• Report Number(s): FERMILAB-PUB-21-319-E; oai:inspirehep.net:1899580; arXiv:2107.09080
• Journal Information: Astrophys.J.Lett., Journal Name: Astrophys.J.Lett. Journal Issue: 2 Vol. 920
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
galaxies: dwarf