We investigate the dependence of the local galaxy luminosity function on morphology using 5404 galaxies from the recently enlarged Second Southern Sky Redshift Survey (SSRS2). Over the range -22 ≥ MB ≥ -14 (Ho = 100 km s-1 Mpc-1), the luminosity function of early-type galaxies is well fitted by a Schechter function with parameters M* = -19.37-0.11+0.10, α = -1.00-0.09+00.9, and Φ* = 4.4 ± 0.8 × 10-3 Mpc-3. The spiral luminosity function is very similar and is well fitted by the parameters M* = -19.43-00.8+00.8, α = -1.11-00.6+00.7, and Φ* = 8.0 ± 1.4 × 10-3 Mpc-3 over the same range in absolute magnitude. The flat faint end of the early-type luminosity function is consistent with earlier measurements from the CfA Redshift Survey (Marzke et al.) but is significantly steeper than the slope measured in the Stromlo-APM survey (Loveday et al.). Combined with the increased normalization of the overall LF measured from intermediate-redshift surveys, the flat faint-end slope of the E/S0 LF produces noevolution models that reproduce the deep Htibble Space Telescope (HST) counts of early-type galaxies remarkably well. However, the observed normalization of the SSRS2 LF is consistent with the low value measured in other local redshift surveys. The cause of this low-redshift anomaly remains unknown. The luminosity function of irregular and peculiar galaxies in the SSRS2 is very steep: M* = -19.78-0.50+0.40, α = -1.81-0.24+0.24, and Φ* = 0.2 ± 0.08 × 10-3 Mpc-3. The steep slope at the faint end is consistent with the LFs measured for Sm-Im galaxies in the CfA survey, UV-selected galaxies (Treyer et al.), starforming field galaxies (Bromley et al.), and the bluest galaxies in the SSRS2 (Marzke & da Costa). As shown by Driver, Windhorst, & Griffiths, the steep LF reduces the observed excess of faint irregulars over no-evolution predictions but cannot explain it entirely.
- Galaxies: Luminosity function, mass function
- Galaxies: Structure
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science