IATE   20350
INSTITUTO DE ASTRONOMIA TEORICA Y EXPERIMENTAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
On the Size Evolution of Early Type Galaxies
Autor/es:
GRANATO, GIAN LUIGI; RAGONE FIGUEROA, CINTHIA
Lugar:
Buenos Aires
Reunión:
Workshop; Second Workshop on Numerical and Observational Astrophysics:"From the First Structures to the Universe Today"; 2011
Institución organizadora:
Instituto de Astronomía y Física del Espacio - IAFE
Resumen:
Observations performed in the last few years indicate that most massive
early-type galaxies (ETGs) observed at redshift z≳ 1 exhibit sizes
smaller by a factor of a few than local ETGs of analogous stellar mass.
We present numerical simulations of the effect of baryonic mass loss on
the structure of a spheroidal stellar system, embedded in a dark matter
halo. This process, invoked as a possible explanation of the observed
size increase of ETGs since z 2, could be caused either by
quasi-stellar object/starburst driven galactic winds, promptly ejecting
from ETGs the residual gas and halting star formation (galactic winds),
or by stellar mass returned to the interstellar medium in the final
stages of stellar evolution. Indeed, we find that a conceivable loss of
50 per cent of the baryonic mass can produce a significant size
increase. However, the puffing up due to galactic winds occurs when the
stellar populations are much younger than the estimated ages ≳0.5
Gyr of compact high-z ETGs. Therefore, while it may have had a role in
deciding the final structure of ETGs, it cannot explain the evolution
observed so far of their size-mass relation; its signature should be
searched for in much younger systems. Conversely, the mass loss due to
stellar evolution could cause a relatively modest expansion of passively
evolving stellar systems later on, contributing to, without dominating,
the observed evolution of their mass-size relationship.