Seminario DAM: "On the origin of dwarf galaxy types and on the building blocks of large spiral galaxies: clues from the Local Group"

Conferenciante: Dra. Carme Gallart Gallart (Instituto Astrofísico de Canarias)

Sitio:    Seminario del Departamento de Astronomía y Meteorología, 7a planta.

Fecha/ Hora:  15-01-2016 / 12:00 

Contacto: carme​am.ub.es

Resumen: I will discuss how precise star formation histories, including details on the earliest star formation events, and the pulsational  properties of RR Lyrae stars can provide important insight into the  origin of the dwarf galaxy types and on the nature of the building  blocks of large spiral galaxies.
First, based on precise SFHs of Local Group dwarf galaxies, I will  show that they 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 at  an early epoch and have continued forming stars until the present time (or almost).
These two evolutionary paths do not map directly onto the present-day   morphology (dwarf spheroidal vs 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. Following  this result, we propose that the nature of a fast or slow dwarf  galaxy is imprinted early on as a consequence of conditions impacting  their mass assembly history. 
At a later stage, interaction with a  large host galaxy may play a role in the final removal of the gas. (Gallart et al. 2015, ApJ 811, L18) 
Second, I will discuss the role that dwarf galaxies may have played  in the formation of the Milky Way and M31 halos using RR Lyrae stars  as tracers of their ancient stellar component. (Fiorentino et al.   2015, ApJ 798, L12; Monelli et al, 2015, in prep)