The K-band luminosity function of nearby field galaxies

We present a measurement of the K-band luminosity function (LF) of field galaxies obtained from near-infrared imaging of a sample of 345 galaxies selected from the Stromlo-APM Redshift Survey. The LF is reasonably well fitted over the 10-mag range -26 less than or equal to M(K)less than or equal to-16 by a Schechter function with parameters alpha=-1.16 +/- 0.19, M*=-23.58 +/- 0.42 and phi*=0.012 +/- 0.008 Mpc(-3), assuming a Hubble constant of H-0=100 km s(-1) Mpc(-1). We have also estimated the LF for two subsets of galaxies subdivided by the equivalent width of the H alpha emission line at EW(H alpha)=10 Angstrom. There is no significant difference in LF shape between the two samples, although there is a hint (similar to 1 sigma significance) that emission-line galaxies (ELGs) have M* roughly 1 mag fainter than non-ELGs. Contrary to the optical LF, there is no difference in faint-end slope alpha between the two samples.