GALAXY FORMATION AND EVOLUTION - LOW-SURFACE-BRIGHTNESS GALAXIES

Citation
R. Jimenez et al., GALAXY FORMATION AND EVOLUTION - LOW-SURFACE-BRIGHTNESS GALAXIES, Monthly Notices of the Royal Astronomical Society, 299(1), 1998, pp. 123-138
Citations number
50
Categorie Soggetti
Astronomy & Astrophysics
ISSN journal
00358711
Volume
299
Issue
1
Year of publication
1998
Pages
123 - 138
Database
ISI
SICI code
0035-8711(1998)299:1<123:GFAE-L>2.0.ZU;2-8
Abstract
We investigate in detail the hypothesis that low-surface-brightness ga laxies (LSBs) differ from ordinary galaxies simply because they form i n haloes with large spin parameters. We compute star formation rates u sing the Schmidt law, assuming the same gas infall dependence on surfa ce density as used in models of the Milky Way. We build stellar popula tion models, predicting colours, spectra and chemical abundances. We c ompare our predictions with observed values of metallicity and colours for LSBs, and find excellent agreement with all observables. In parti cular, integrated colours, colour gradients, surface brightness and me tallicity match very well to the observed values of LSBs for models wi th ages larger than 7 Gyr and high values (lambda > 0.05) for the spin parameter of the haloes. We also compute the global star formation ra te (SFR) in the Universe due to LSBs, and show that it has a flatter e volution with redshift than the corresponding SFR for normal discs. We furthermore compare the evolution in redshift of [Zn/H] for our model s to those observed in damped Lyman a systems by Pettini et al. and sh ow that damped Lyman a! system abundances are consistent with the pred icted abundances at different radii for LSBs. Finally, we show how the required late redshift of collapse of the halo may constrain the powe r spectrum of fluctuations.