The ACS LCID Project: On the Origin of Dwarf Galaxy Types—A Manifestation of the Halo Assembly Bias?

Gallart, C.; Monelli, M.; Mayer, L.; Aparicio, A.; Battaglia, G.; Bernard, Edouard J.; Cassisi, Santi; Cole, Andrew A.; Dolphin, Andrew E.; Drozdovsky, I.; Hidalgo, S. L.; Navarro, Julio F.; Salvadori, Stefania; Skillman, Evan D.; Stetson, Peter B.; Weisz, Daniel R.
Referencia bibliográfica

The Astrophysical Journal Letters, Volume 811, Issue 2, article id. L18, 6 pp. (2015).

Fecha de publicación:
10
2015
Número de autores
16
Número de autores del IAC
6
Número de citas
105
Número de citas referidas
96
Descripción
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. Based on observations made with the NASA/ESA HST, which is operated by the AURA, under NASA contract NAS5-26555. Observations associated with programs #8706, #10505, and #10590.
Proyectos relacionados
Cúmulo Globular NGC 2808
Vía Láctea y galaxias cercanas
El objetivo general del Proyecto es el estudio de la estructura, historia evolutiva y proceso de formación de galaxias a través de sus poblaciones estelares resueltas, tanto a partir de fotometría como espectroscopia. El proyecto puede dividirse en cuatro líneas principales: I. Historia de formación estelar en el Grupo Local. El objetivo de esta
Martín
López Corredoira
Una vista de nuestra galaxia, la Vía Láctea, con sus vecinos cercanos,  las Nubes de Magallanes
Evolución Galáctica en el Grupo Local
La formación y evolución de galaxias es un problema fundamental en Astrofísica. Su estudio requiere “viajar atrás en el tiempo”, para lo cual hay dos enfoques complementarios. El mas extendido consiste en analizar las propiedades de las galaxias a diferentes distancias cosmológicas. Nuestro equipo se concentra en el otro enfoque, denominado
Matteo
Monelli