Chemically consistent evolution of galaxies *
Spiral galaxy models compared to DLA systems
U. Fritze - von Alvensleben and
Received 30 June 1998 / Accepted 27 October 1998
We have extended our chemical and cosmological galaxy evolution model to calculate the abundance evolution for altogether 16 different elements in spiral galaxies in a chemically consistent way which is a considerable step towards a more realistic galaxy modeling. All observed element abundances in DLA systems have been compiled. The comparison with our model calculations yields the following results.
Together with the fact that our models well reproduce observed average HII region abundances in all spiral types the conformity between observed and calculated abundances over the redshift range from through indicates that DLA galaxies may well evolve into the full range of present-day spiral galaxies from Sa through Sd.
Comparison of our chemically consistent models with models using only solar metallicity input physics shows that differences in the redshift evolution are small for some elements but large for others. For those elements with large differences the chemically consistent models provide significant better agreement with observed DLA abundances.
For typical spiral galaxies the star formation histories of our models clearly bridge the gap between high redshift DLA systems and the nearby spiral galaxy population. The slow redshift evolution of DLA abundances is understood in terms of the long star formation timescales in galactic and proto-galactic disks. The large scatter of observed abundances in DLAs of similar redshift is rather explained by the range of SFRs among early and late type spirals.
Towards lower redshift our models
indicate that early type spirals drop out of the DLA samples as their
gas content falls below . Implications
for optical identification are discussed.
Key words: galaxies: evolution galaxies: quasars: absorption lines
* Tables 5 to 9 are only available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr/pub/cats/J/A+A/341/709 (126.96.36.199) or via
Send offprint requests to: U. Lindner
© European Southern Observatory (ESO) 1999
Online publication: December 16, 1998