The Next Generation Virgo Cluster Survey. XXII. Shell Feature Early-type Dwarf Galaxies in the Virgo Cluster

Creators: Paudel, Sanjaya; Smith, Rory; Duc, Pierre-Alain; Côté, Patrick; Cuillandre, Jean-Charles; Ferrarese, Laura; Blakeslee, John P.; Boselli, Alessandro; Cantiello, Michele; Gwyn, S. D. J.; Guhathakurta, Puragra; Mei, Simona; Mihos, J. Christopher; Peng, Eric W.; Powalka, Mathieu; Sánchez-Janssen, Rubén; Toloba, Elisa; Zhang, Hongxin

Abstract

The Next Generation Virgo Cluster Survey is a deep (with a 2σ detection limit μ_g = 29 mag arcsec^(−2) in the g-band) optical panchromatic survey targeting the Virgo cluster from its core to virial radius, for a total areal coverage of 104 square degrees. As such, the survey is well suited for the study of galaxies' outskirts, haloes, and low surface brightness features that arise from dynamical interactions within the cluster environment. We report the discovery of extremely faint (μ_g > 25 mag arcsec^(−2)) shells in three Virgo cluster early-type dwarf galaxies: VCC 1361, VCC 1447, and VCC 1668. Among them, VCC 1447 has an absolute magnitude M_g = −11.71 mag and is the least massive galaxy with a shell system discovered to date. We present a detailed study of these low surface brightness features. We detect between three and four shells in each of our galaxies. Within the uncertainties, we find no evidence of a color difference between the galaxy main body and shell features. The observed arcs of the shells are located up to several effective radii of the galaxies. We further explore the origin of these low surface brightness features with the help of idealized numerical simulations. We find that a near equal mass merger is best able to reproduce the main properties of the shells, including their quite symmetric appearance and their alignment along the major axis of the galaxy. The simulations provide support for a formation scenario in which a recent merger, between two near-equal mass, gas-free dwarf galaxies, forms the observed shell systems.

Additional Information

© 2017. The American Astronomical Society. Received 2016 September 23; revised 2016 November 7; accepted 2016 November 10; published 2017 January 3. This work is supported by the French Agence Nationale de la Recherche (ANR) Grant Programme Blanc VIRAGE (ANR10-BLANC-0506-01). We wish to express our gratitude to the CFHT personnel for their dedication and tremendous help with the MegaCam observations. R.S. acknowledges support from Brain Korea 21 Plus Program (21A20131500002) and the Doyak Grant (2014003730). E.W.P. acknowledges support from the National Natural Science Foundation of China under Grant No. 11573002, and from the Strategic Priority Research Program, "The Emergence of Cosmological Structures," of the Chinese Academy of Sciences, Grant No. XDB09000105. E.T. and R.G. acknowledge the NSF grants AST-1010039 and AST-1412504. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency. The authors further acknowledge use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada–France–Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

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