Rediscovery of the Sixth Star Cluster in the Fornax Dwarf Spheroidal Galaxy

Wang, M. Y.; Koposov, S.; Drlica-Wagner, A.; Pieres, A.; Li, T. S.; de Boer, T.; Bechtol, K.; Belokurov, V.; Pace, A. B.; Bacon, D.; Abbott, T. M.  C.; Annis, J.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; da Costa, L. N.; De Vicente, J.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Hollowood, D. L.; Honscheid, K.; Hoyle, B.; James, D. J.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Maia, M. A.  G.; Marshall, J. L.; Menanteau, F.; Miquel, R.; Plazas, A. A.; Sanchez, E.; Santiago, B.; Scarpine, V.; Schindler, R.; Schubnell, M.; Serrano, S.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Sobreira, F.; Suchyta, E.; Swanson, M. E.  C.; Tarle, G.; Thomas, D.; Tucker, D. L.; Walker, A. R.

doi:10.3847/2041-8213/ab14f5

Title: Rediscovery of the Sixth Star Cluster in the Fornax Dwarf Spheroidal Galaxy

Journal Article · Tue Apr 16 00:00:00 EDT 2019 · The Astrophysical Journal. Letters (Online)

DOI:https://doi.org/10.3847/2041-8213/ab14f5· OSTI ID:1526932

;

; Pieres, A.;

; de Boer, T.; Bechtol, K.; Belokurov, V.;

;

; Bertin, E.;

; Buckley-Geer, E.;

; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; da Costa, L. N. more »

Since first noticed by Shapley in 1939, a faint object coincident with the Fornax dwarf spheroidal has long been discussed as a possible sixth globular cluster system. However, debate has continued over whether this overdensity is a statistical artifact or a blended galaxy group. In this Letter we demonstrate, using deep DECam imaging data, that this object is well resolved into stars and is a bona fide star cluster. The stellar overdensity of this cluster is statistically significant at the level of ~ 6 - 6.7 sigma in several different photometric catalogs including Gaia. Therefore, it is highly unlikely to be caused by random fluctuation. We show that Fornax 6 is a star cluster with a peculiarly low surface brightness and irregular shape, which may indicate a strong tidal influence from its host galaxy. The Hess diagram of Fornax 6 is largely consistent with that of Fornax field stars, but it appears to be slightly bluer. However, it is still likely more metal-rich than most of the globular clusters in the system. Faint clusters like Fornax 6 that orbit and potentially get disrupted in the centers of dwarf galaxies can prove crucial for constraining the dark matter distribution in Milky Way satellites.

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Research Organization:: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Univ. of Michigan, Ann Arbor, MI (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

Sponsoring Organization:: USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)

Contributing Organization:: DES Collaboration

Grant/Contract Number:: AC02-76SF00515; AC02-07CH11359; AC05-00OR22725; AST-1813881; AST-1138766; AST- 1536171; AYA2015-71825; ESP2015-66861; FPA2015-68048; SEV- 2016-0588; SEV-2016-0597; MDM-2015-0509; SC0019193

OSTI ID:: 1526932

Alternate ID(s):: OSTI ID: 1531224; OSTI ID: 1546032; OSTI ID: 1726010

Report Number(s):: arXiv:1902.04589; FERMILAB-PUB-19-195-AE-CD

Journal Information:: The Astrophysical Journal. Letters (Online), Vol. 875, Issue 2; ISSN 2041-8213

Publisher:: Institute of Physics (IOP)Copyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 15 works

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Embedding globular clusters in dark matter minihaloes solves the cusp–core and timing problems in the Fornax dwarf galaxy Boldrini, Pierre; Mohayaee, Roya; Silk, Joseph Monthly Notices of the Royal Astronomical Society, Vol. 492, Issue 3 https://doi.org/10.1093/mnras/staa011	journal	January 2020
An old, metal-poor globular cluster in Sextans A and the metallicity floor of globular cluster systems Beasley, Michael A.; Leaman, Ryan; Gallart, Carme Monthly Notices of the Royal Astronomical Society, Vol. 487, Issue 2 https://doi.org/10.1093/mnras/stz1349	journal	May 2019
Globular clusters as probes of dark matter cusp-core transformations Orkney, M. D. A.; Read, J. I.; Petts, J. A. Monthly Notices of the Royal Astronomical Society, Vol. 488, Issue 3 https://doi.org/10.1093/mnras/stz1625	journal	June 2019
Globular clusters as probes of dark matter cusp-core transformations Orkney, M. D. A.; Read, J. I.; Petts, James A. arXiv https://doi.org/10.48550/arxiv.1906.04759	text	January 2019

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