We present measurements of the galaxy luminosity and stellar mass function in a 3.71 deg ^ { 2 } ( 0.3 Mpc ^ { 2 } ) area in the core of the Virgo cluster , based on u ^ { * } griz data from the Next Generation Virgo Cluster Survey ( NGVS ) .
The galaxy sample — which consists of 352 objects brighter than M _ { g } = -9.13 mag , the 50 % completeness limit of the survey — reaches 2.2 mag deeper than the widely used Virgo Cluster Catalog ( VCC ) and at least 1.2 mag deeper than any sample previously used to measure the luminosity function in Virgo .
Using a Bayesian analysis , we find a best-fit faint end slope of \alpha = -1.33 \pm 0.02 for the g - band luminosity function ; consistent results are found for the stellar mass function as well as the luminosity function in the other four NGVS bandpasses .
We discuss the implications for the faint-end slope of adding 92 ultra compact dwarfs galaxies ( UCDs ) — previously compiled by the NGVS in this region — to the galaxy sample , assuming that UCDs are the stripped remnants of nucleated dwarf galaxies .
Under this assumption , the slope of the luminosity function ( down to the UCD faint magnitude limit , M _ { g } = -9.6 mag ) increases dramatically , up to \alpha = -1.60 \pm 0.06 when correcting for the expected number of disrupted non-nucleated galaxies .
We also calculate the total number of UCDs and globular clusters that may have been deposited in the core of Virgo due to the disruption of satellites , both nucleated and non-nucleated .
We estimate that \sim 150 objects with M _ { g } \lesssim - 9.6 mag and that are currently classified as globular clusters , might , in fact , be the nuclei of disrupted galaxies .
We further estimate that as many as 40 % of the ( mostly blue ) globular clusters in the Virgo core might once have belonged to such satellites ; these same disrupted satellites might have contributed \sim 40 % of the total luminosity in galaxies observed in the core region today .
Finally , we use an updated Local Group galaxy catalog to provide a new measurement of the luminosity function of Local Group satellites , \alpha = -1.21 \pm 0.05 , which is only 1.7 \sigma shallower than measured in the core of the Virgo cluster .