Issue |
A&A
Volume 402, Number 1, April IV 2003
|
|
---|---|---|
Page(s) | 65 - 78 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20021898 | |
Published online | 07 April 2003 |
Star forming rates between z = 0.25 and z = 1.2 from the CADIS emission line survey
1
Max–Planck–Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
2
Department of Physics, Denys Wilkinson Bldg., University of Oxford, Keble Road, Oxford, OX1 3RH, UK
Corresponding author: H. Hippelein, hippelei@mpia-hd.mpg.de
Received:
15
May
2002
Accepted:
23
December
2002
The emission line survey within the Calar Alto Deep Imaging Survey
(CADIS) detects emission line galaxies by a scan with an imaging
Fabry-Perot interferometer. It covers 5 fields of
each in three wavelengths windows centered on
,
820, and 920 nm, and reaches to a typical limiting line flux of
W m-2. This is the deepest emission line survey covering
a field of several 100
. Galaxies between
and
are detected by prominent emission lines (from Hα to
[O ii]372.7) falling into the FP scans. Additional observations with a
dozen medium band filters allow to establish the line identification
and thus the redshift of the galaxies to better than
. On the basis of a total of more than 400 emission line galaxies
detected in Hα (92 galaxies), [O iii]500.7 (124 galaxies),
or [O ii]372.7 (222 galaxies) we measure the instantaneous star
formation rate (SFR) in the range
. With this purely emission line selected sample we
are able to reach much fainter emission line galaxies than previous,
continuum-selected samples. Thus completeness corrections are much
less important. Although the relative [O iii] emission line
strength depends on excitation and metallicity and shows strong variation,
the mean line ratios yield SFR[O iii] values consistent with the
SFR evolution.
Our results substantiates the indications from previous studies (based
on small galaxy samples) that the SFR decreases by a factor of ~20
between
and today. In fact, for a
cosmology, we find an exponential
decline
Gyr).
This decrease of the SFR with time follows an exponential law which is
compatible with the decreasing galaxy merger rate as expected from model
calculations.
The inferred SF density is in perfect agreement with that
deduced from the FIR emission of optically selected galaxies which
is explained by a large overlap between both populations. We show that
self-consistent extinction corrections of both our emission lines and
the UV continua lead to consistent results for the SF density.
Key words: stars: formation / galaxies: general / galaxies: high-redshift / galaxies: luminosity function
© ESO, 2003
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