We examine a sample of low-redshift (10 h-1 Mpc < d < 150 h-1 Mpc) field galaxies including galaxies with luminosities as low as Mr - 5 log h ∼ -12.5, selected from the Sloan Digital Sky Survey Data Release 2 (SDSS DR2). The sample is unique in containing galaxies of extremely low luminosities in a wide range of environments, selected with uniform and well-understood criteria. We present the luminosity function, as well as the broadband properties, of low-luminosity galaxies in this sample. A Schechter function is an insufficient parameterization of the r-band luminosity function; there is an upturn in the slope for Mr - 5 log h > -18. The resulting slope at low luminosities in this sample is α2 ∼ -1.3. However, we almost certainly miss a large number of galaxies at very low luminosities due to low surface brightness selection effects, and we estimate that the true low-luminosity slope may be as steep as or steeper than α2 ∼ -1.5. The results here are consistent with previous SDSS results and, in the g band, roughly consistent with the results of the Two Degree Field Galaxy Redshift Survey. Extremely low luminosity galaxies are predominantly low surface brightness, exponential disks, the majority of which are red.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science