We present the stellar mass functions ( SMF ) and mass densities of galaxies , and their spheroid and disk components in the local ( z \sim 0.1 ) universe over the range 8.9 \leq log ( M / M _ { \odot } ) \leq 12 from spheroid+disk decompositions and corresponding stellar masses of a sample of over 600,000 galaxies in the SDSS-DR7 spectroscopic sample .
The galaxy SMF is well represented by a single Schechter function ( M ^ { * } = 11.116 \pm 0.011 , \alpha = -1.145 \pm 0.008 ) , though with a hint of a steeper faint end slope .
The corresponding stellar mass densities are ( 2.670 \pm 0.110 ) , ( 1.687 \pm 0.063 ) and ( 0.910 \pm 0.029 ) \times 10 ^ { 8 } M _ { \odot } { \mathrm { Mpc } } ^ { -3 } for galaxies , spheroids and disks respectively .
We identify a crossover stellar mass of log ( M / M _ { \odot } ) = 10.3 \pm 0.030 at which the spheroid and disk SMFs are equal .
Relative contributions of four distinct spheroid/disk dominated sub-populations to the overall galaxy SMF are also presented .
The mean disk-to-spheroid stellar mass ratio shows a five fold disk dominance at the low mass end , decreasing monotonically with a corresponding increase in the spheroidal fraction till the two are equal at a galaxy stellar mass , log ( M / M _ { \odot } ) =10.479 \pm 0.013 ; the dominance of spheroids then grows with increasing stellar mass .
The relative numbers of composite disk and spheroid dominated galaxies show peaks in their distributions , perhaps indicative of a preferred galaxy mass .
Our characterization of the low redshift galaxy population provides stringent constraints for numerical simulations to reproduce .