A large sample of low surface brightness disk galaxies from the SDSS. I: The sample and the stellar populations
Abstract
We present the properties of a large sample (12,282) of nearly face-on low surface brightness (LSB) disk galaxies selected from the main galaxy sample of SDSS-DR4. These properties include B-band central surface brightness mu0(B), scale lengths h, integrated magnitudes, colors, and distances D. This sample has mu0(B) values from 22 to 24.5 mag arcsec-2 with a median value of 22.42 mag arcsec-2, and disk scale lengths ranging from 2 to 19 kpc. They are quite bright with MB taking values from -18 to -23 mag with a median value of -20.08 mag. There exist clear correlations between logh and MB, logh and logD, logD and MB. However, no obvious correlations are found between mu0(B) and logh, colors etc. The correlation between colors and logh is weak even though it exists. Both the optical-optical and optical-NIR color-color diagrams indicate that most of them have a mixture of young and old stellar populations. They also satisfy color-magnitude relations, which indicate that brighter galaxies tend generally to be redder. The comparison between the LSBGs and a control sample of nearly face-on disk galaxies with higher surface brightness (HSB) with mu0(B) from 18.5 to 22 mag arcsec-2 show that, at a given luminosity or distance, the observed LSB galaxies tend to have larger scale lengths. These trends could be seen gradually by dividing both the LSBGs and HSBGs into two sub-groups according to surface brightness. A volume-limited sub-sample was extracted to check the incompleteness of surface brightness. The only one of the property relations having an obvious change is the relation of logh versus mu0(B), which shows a correlation in this sub-sample.