Satellite Dwarf Galaxies in a Hierarchical Universe: The Prevalence of Dwarf-Dwarf Major Mergers
Abstract
Mergers are a common phenomenon in hierarchical structure formation, especially for massive galaxies and clusters, but their importance for dwarf galaxies in the Local Group remains poorly understood. We investigate the frequency of major mergers between dwarf galaxies in the Local Group using the ELVIS suite of cosmological zoom-in dissipationless simulations of Milky Way- and M31-like host halos. We find that ~10% of satellite dwarf galaxies with Mstar > 10^6 M_☉ that are within the host virial radius experienced a major merger of stellar mass ratio closer than 0.1 since z = 1, with a lower fraction for lower mass dwarf galaxies. Recent merger remnants are biased toward larger radial distance and more recent virial infall times, because most recent mergers occurred shortly before crossing within the virial radius of the host halo. Satellite–satellite mergers also occur within the host halo after virial infall, catalyzed by the large fraction of dwarf galaxies that fell in as part of a group. The merger fraction doubles for dwarf galaxies outside of the host virial radius, so the most distant dwarf galaxies in the Local Group are the most likely to have experienced a recent major merger. We discuss the implications of these results on observable dwarf merger remnants, their star formation histories, the gas content of mergers, and massive black holes in dwarf galaxies.
Additional Information
© 2014 The American Astronomical Society. Received 2014 June 12; accepted 2014 August 18; published 2014 September 30. A.J.D. is currently supported by NASA through Hubble Fellowship grant HST-HF-51302.01, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. We thank the Aspen Center for Physics and National Science Foundation grant #1066293 for hospitality during the writing of this paper. We thank Nicola Amorisco, Vasily Belokurov, Gurtina Besla, Laura Blecha, and Wyn Evans for useful discussion. We also thank the anonymous referee for useful comments.Attached Files
Published - 0004-637X_794_2_115.pdf
Submitted - 1406.3344v2.pdf
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Additional details
- Eprint ID
- 51789
- Resolver ID
- CaltechAUTHORS:20141114-132347544
- HST-HF-51302.01
- NASA Hubble Fellowship
- NAS5-26555
- NASA
- Aspen Center for Physics
- PHY-1066293
- NSF
- Created
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2014-11-14Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field