The K-band galaxy luminosity function

We measured the K-band luminosity function using a complete sample of 4192 morphologically typed 2MASS galaxies with mu (K s) = 20 mag arcsec(-2) isop hotal magnitudes 7<K-20<11.25 mag spread over 2.12 sr. Early-type (T <less than or equal to> -0.5) and late-type (T > -0.5) galaxies have similarly sh aped luminosity functions, alpha (e) = -0.92 +/-0.10 and alpha (l) = -0.87 +/-0.09. The early-type galaxies are brighter, M-K*e = -23.53 +/-0.06 mag c ompared to M-K*l = -22.98 +/-0.06 mag, but less numerous, n(*e) = (0.45 +/- 0.06)x10(-2) Mpc(-3) compared to N-*l = (1.01 +/-0.13)x10(-2) h(3) Mpc(-3) for H-0 = 100 h km s(-1) Mpc(-1), such that the late-type galaxies slightly dominate the K-band luminosity density, j(late)/j(early) = 1.17 +/-0.12. I ncluding a factor of 1.20 +/-0.04 correction for the conversion of the isop hotal survey magnitudes to total magnitudes, the local K-band luminosity de nsity is j = (7.14 +/-0.75)x10(8) h L-circle dot Mpc(-3), which implies a s tellar mass density relative to critical of Omega (*)h = (1.9 +/-0.2)x10(-3 ) for a Kennicutt initial mass function (IMF) and Omega (*)h = (3.4 +/-0.4) x10(-3) for a Salpeter IMF. Our morphological classifications are internall y consistent, are consistent with previous classifications, and lead to lum inosity functions unaffected by the estimated uncertainties in the classifi cations. These luminosity functions accurately predict the K-band number co unts and redshift distributions for K less than or similar to 18 mag, beyon d which the results depend on galaxy evolution and merger histories.