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
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.