Bibcode
Weidner, C.; Ferreras, Ignacio; Vazdekis, A.; La Barbera, Francesco
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 435, Issue 3, p.2274-2280
Fecha de publicación:
11
2013
Número de citas
79
Número de citas referidas
72
Descripción
Recent evidence based independently on spectral line strengths and
dynamical modelling point towards a non-universal stellar initial mass
function (IMF), probably implying an excess of low-mass stars in
elliptical galaxies with a high velocity dispersion. Here, we show that
a time-independent bottom-heavy IMF is compatible neither with the
observed metal-rich populations found in giant ellipticals nor with the
number of stellar remnants observed within these systems. We suggest a
two-stage formation scenario involving a time-dependent IMF to reconcile
these observational constraints. In this model, an early strong
starbursting stage with a top-heavy IMF is followed by a more prolonged
stage with a bottom-heavy IMF. Such model is physically motivated by the
fact that a sustained high star formation will bring the interstellar
medium to a state of pressure, temperature and turbulence that can
drastically alter the fragmentation of the gaseous component into small
clumps, promoting the formation of low-mass stars. This toy model is in
good agreement with the different observational constrains on massive
elliptical galaxies, such as age, metallicity, α-enhancement,
mass-to-light ratio or the mass fraction of the stellar component in
low-mass stars.
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