Search for RR Lyrae stars in DES ultrafaint systems: Grus I, Kim 2, Phoenix II, and Grus II

Journal Article · Tue Sep 24 00:00:00 EDT 2019 · Monthly Notices of the Royal Astronomical Society

DOI:https://doi.org/10.1093/mnras/stz2609· OSTI ID:1664588

Martínez-Vázquez, C. E.  ^[1]; Vivas, A. K.  ^[1]; Gurevich, M. ^[1]; Walker, A. R. ^[1]; McCarthy, M. ^[2]; Pace, A. B.  ^[3]; Stringer, K. M. ^[3]; Santiago, B. ^[4]; Hounsell, R. ^[5]; Macri, L. ^[3]; Li, T. S. ^[6]; Bechtol, K. ^[7]; Riley, A. H.  ^[3]; Kim, A. G. ^[8]; Simon, J. D. ^[9]; Drlica-Wagner, A. ^[6]; Nadler, E. O. ^[10]; Marshall, J. L. ^[3]; Annis, J. ^[11]; Avila, S.  ^[12] ; Bertin, E. ^[13]; Brooks, D. ^[14]; Buckley-Geer, E. ^[11]; Burke, D. L. ^[15]; Carnero Rosell, A.  ^[16]; Carrasco Kind, M. ^[17]; da Costa, L. N. ^[18]; De Vicente, J. ^[19]; Desai, S. ^[20]; Diehl, H. T. ^[11]; Doel, P. ^[14]; Everett, S. ^[21]; Frieman, J. ^[6]; García-Bellido, J. ^[12]; Gaztanaga, E. ^[22]; Gruen, D.  ^[23]; Gruendl, R. A. ^[17]; Gschwend, J. ^[18]; Gutierrez, G. ^[11]; Hollowood, D. L. ^[21]; Honscheid, K. ^[24]; James, D. J. ^[25]; Kuehn, K. ^[26]; Kuropatkin, N. ^[11]; Maia, M. A. G. ^[18]; Menanteau, F. ^[17]; Miller, C. J. ^[27]; Miquel, R. ^[28]; Paz-Chinchón, F. ^[17]; Plazas, A. A.  ^[29]; Sanchez, E. ^[19]; Scarpine, V. ^[11]; Serrano, S. ^[22]; Sevilla-Noarbe, I. ^[19]; Smith, M. ^[30]; Soares-Santos, M.  ^[31]; Sobreira, F. ^[32]; Swanson, M. E. C. ^[33]; Tarle, G. ^[34]; Vikram, V. ^[35]

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1. Cerro Tololo Inter-American Observatory, NSF’s National Optical-Infrared Astronomy Research Laboratory, Casilla 603, La Serena, Chile
2. Department of Physics & Astronomy, University of Rochester, 500 Joseph C. Wilson Blvd, Rochester, NY 14627, USA
3. George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA
4. Instituto de Física, UFRGS, Caixa Postal 15051, Porto Alegre, RS - 91501-970, Brazil, Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil
5. Department of Physics & Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104-6396, USA
6. Fermi National Accelerator Laboratory, PO Box 500, Batavia, IL 60510, USA, Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA
7. LSST, 933 North Cherry Avenue, Tucson, AZ 85721, USA, Department of Physics, 2320 Chamberlin Hall, University of Wisconsin-Madison, 1150 University Avenue Madison, WI 53706-1390, USA
8. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
9. Observatories of the Carnegie Institution for Science, 813 Santa Barbara St, Pasadena, CA 91101, USA
10. Kavli Institute for Particle Astrophysics & Cosmology, PO Box 2450, Stanford University, Stanford, CA 94305, USA
11. Fermi National Accelerator Laboratory, PO Box 500, Batavia, IL 60510, USA
12. Instituto de Fisica Teorica UAM/CSIC, Universidad Autonoma de Madrid, E-28049 Madrid, Spain
13. CNRS, UMR 7095, Institut d’Astrophysique de Paris, F-75014 Paris, France, Sorbonne Universités, UPMC Univ Paris 06, UMR 7095, Institut d’Astrophysique de Paris, F-75014 Paris, France
14. Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
15. Kavli Institute for Particle Astrophysics & Cosmology, PO Box 2450, Stanford University, Stanford, CA 94305, USA, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
16. Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), E-28040 Madrid, Spain
17. Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801, USA, National Center for Supercomputing Applications, 1205 West Clark St, Urbana, IL 61801, USA
18. Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil
19. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), E-28040 Madrid, Spain
20. Department of Physics, IIT Hyderabad, Kandi, Telangana 502285, India
21. Santa Cruz Institute for Particle Physics, Santa Cruz, CA 95064, USA
22. Institut d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Spain, Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain
23. Kavli Institute for Particle Astrophysics & Cosmology, PO Box 2450, Stanford University, Stanford, CA 94305, USA, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA, Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305, USA
24. Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA
25. Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
26. Australian Astronomical Optics, Macquarie University, North Ryde, NSW 2113, Australia, Lowell Observatory, 1400 Mars Hill Rd, Flagstaff, AZ 86001, USA
27. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA, Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
28. Institució Catalana de Recerca i Estudis Avançats, E-08010 Barcelona, Spain, Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, E-08193 Bellaterra (Barcelona) Spain
29. Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544, USA
30. School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK
31. Department of Physics, Brandeis University, 415 South Street, Waltham, MA 02453, USA
32. Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, 13083-859, Campinas, SP, Brazil
33. National Center for Supercomputing Applications, 1205 West Clark St, Urbana, IL 61801, USA
34. Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
35. Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439, USA

Here, we introduce the first search for RR Lyrae stars (RRLs) in four of the ultra-faint systems imaged by the Dark Energy Survey (DES) using SOAR/Goodman and Blanco/DECam imagers. We have detected two RRLs in the field of Grus I, none in Kim 2, one in Phoenix II, and four in Grus II. With the detection of these stars, we accurately determine the distance moduli for these ultra-faint dwarf satellite galaxies; μ₀=20.51±0.10 mag (D_⊙=127±6 kpc) for Grus I and μ₀=20.01±0.10 mag (D_⊙=100±5 kpc) for Phoenix II. These measurements are larger than previous estimations by Koposov et al. 2015 and Bechtol et al. 2015, implying larger physical sizes; 5% for Grus I and 33% for Phoenix II. For Grus II, out of the four RRLs detected, one is consistent with being a member of the galactic halo (D_⊙=24±1 kpc, μ₀=16.86±0.10 mag), another is at D_⊙=55±2 kpc (μ₀=18.71±0.10 mag), which we associate with Grus II, and the two remaining at D_⊙=43±2 kpc (μ₀=18.17±0.10 mag). Furthermore, the appearance of a subtle red horizontal branch in the color-magnitude diagram of Grus II at the same brightness level of the latter two RRLs, which are at the same distance and in the same region, suggests that a more metal-rich system may be located in front of Grus II. The most plausible scenario is the association of these stars with the Chenab/Orphan Stream. Finally, we performed a comprehensive and updated analysis of the number of RRLs in dwarf galaxies. This allows us to predict that the method of finding new ultra-faint dwarf galaxies by using two or more clumped RRLs will work only for systems brighter than MV ~ -6 mag.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Univ. of Michigan, Ann Arbor, MI (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Contributing Organization: DES Collaboration
• Grant/Contract Number: AC02-07CH11359; SC0019193
• OSTI ID: 1664588
• Alternate ID(s): OSTI ID: 1570191; OSTI ID: 1679945
• Report Number(s): arXiv:1909.06308; FERMILAB-PUB-19-287-AE; DES-2019-0437
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Vol. 490 Journal Issue: 2; ISSN 0035-8711
• Publisher: Royal Astronomical Society
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
Galaxies: dwarf
galaxies: individual (Grus I
Kim 2
Phoenix II
Grus II)
stars: horizontal-branch
stars: variables: RR Lyrae