Galaxy and Mass Assembly (GAMA): Z ~ 0 galaxy luminosity function down to L ~ 10⁶ L_⊙ via clustering based redshift inference

In this study, we present a new experimental design using clustering-based redshift inference to measure the evolving galaxy luminosity function (GLF) spanning 5.5 decades from L ∼1011.5 to 106 L. We use data from the Galaxy And Mass Assembly (GAMA) survey and the Kilo-Degree Survey (KiDS). We derive redshift distributions in bins of apparent magnitude to the limits of the GAMA-KiDS photometric catalogue: mr 23; more than a decade in luminosity beyond the limits of the GAMA spectroscopic redshift sample via clustering-based redshift inference. This technique uses spatial cross-correlation statistics for a reference set with known redshifts (in our case, the main GAMA sample) to derive the redshift distribution for the target ensemble. For the calibration of the redshift distribution, we use a simple parametrization with an adaptive normalization factor over the interval 0.005 < z < 0.48 to derive the clustering redshift results. We find that the GLF has a relatively constant power-law slope α ≈-1.2 for-17 Mr-13, and then appears to steepen sharply for-13 Mr-10. This upturn appears to be where globular clusters (GCs) take over to dominate the source counts as a function of luminosity. Thus, we have mapped the GLF across the full range of the z ∼0 field galaxy population from the most luminous galaxies down to the GC scale.