Issue |
A&A
Volume 454, Number 1, July IV 2006
|
|
---|---|---|
Page(s) | 67 - 76 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20053387 | |
Published online | 03 July 2006 |
The impact of starbursts and post-starbursts on the photometric evolution of high redshift galaxies
1
Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Herts AL10 9AB, UK e-mail: ufritze@star.herts.ac.uk
2
Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
Received:
9
May
2005
Accepted:
29
October
2005
We present evolutionary synthesis models for galaxies of
spectral types Sa through Sd
with starbursts of various strengths triggered at various redshifts and
study their
photometric evolution before, during, and after their bursts in a cosmological
context. We find that bursts at high redshift, even very strong ones,
only cause a small
blueing of their intrinsically blue young parent galaxies. At lower redshift,
in contrast, even small bursts cause a significant blueing of their
intrinsically redder
galaxies. While the burst phase is generally short, typically a few hundred Myr in normal-mass galaxies,
the postburst stage with its red colors and, in particular the very red ones
for early bursts at high
redshift, lasts much longer, on the order of several Gyr. We find that,
even without any dust, which in the postburst stage is not expected to play
an important role
anyway, models easily reach the colors of EROs in the redshift range through
after starbursts at redshifts between 2 and 4. We therefore propose a third alternative for the ERO galaxies beyond the two
established ones of passive galaxies vs. dusty starbursts: the
dust-free post-(strong-)starbursts.
A very first comparison of our models to HDF data with photometric redshifts
shows that
almost all of the outliers that could not be described with our chemically
consistent models for undisturbed normal
galaxy types E through Sd can now be explained very well.
Galaxies in the redshift
range from
to
that are redder, and in some cases much
redder, than our reddest undisturbed model for a high-metallicity classical
elliptical are well described by post-starburst
models after starbursts at redshifts between 2 and 4. Galaxies bluer than our bluest low metallicity Sd model, most of which have
redshifts lower than 1, are well explained by ongoing starbursts.
Key words: Galaxy: formation / galaxies: evolution / galaxies: starbursts / galaxies: high-redshift
© ESO, 2006
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