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The ACS LCID project: on the origin of dwarf galaxy types - a manifestation of the halo assembly bias?


Gallart, C and Monelli, M and Mayer, L and Aparicio, A and Battaglia, G and Bernard, EJ and Cassisi, S and Cole, AA and Dolphin, AE and Drozdovsky, I and Hidalgo, SL and Navarro, JF and Salvadori, S and Skillman, ED and Stetson, PB and Weisz, DR, The ACS LCID project: on the origin of dwarf galaxy types - a manifestation of the halo assembly bias?, Astrophysical Journal Letters, 811, (2) Article L18. ISSN 2041-8205 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 The American Astronomical Society

DOI: doi:10.1088/2041-8205/811/2/L18


We discuss how knowledge of the whole evolutionary history of dwarf galaxies, including details on the early star formation events, can provide insight on the origin of the different dwarf galaxy types. We suggest that these types may be imprinted by the early conditions of formation rather than only being the result of a recent morphological transformation driven by environmental effects. We present precise star formation histories of a sample of Local Group dwarf galaxies, derived from color–magnitude diagrams reaching the oldest main-sequence turnoffs. We argue that these galaxies can be assigned to two basic types: fast dwarfs that started their evolution with a dominant and short star formation event and slow dwarfs that formed a small fraction of their stars early and have continued forming stars until the present time (or almost). These two different evolutionary paths do not map directly onto the present-day morphology (dwarf spheroidal versus dwarf irregular). Slow and fast dwarfs also differ in their inferred past location relative to the Milky Way and/or M31, which hints that slow dwarfs were generally assembled in lower-density environments than fast dwarfs. We propose that the distinction between a fast and slow dwarf galaxy primarily reflects the characteristic density of the environment where they form. At a later stage, interaction with a large host galaxy may play a role in the final gas removal and ultimate termination of star formation.

Item Details

Item Type:Refereed Article
Keywords:dwarf galaxies, galaxy formation, Local Group, stellar populations
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Cole, AA (Professor Andrew Cole)
ID Code:105923
Year Published:2015
Web of Science® Times Cited:62
Deposited By:Mathematics and Physics
Deposited On:2016-01-20
Last Modified:2019-11-29

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