Galaxy And Mass Assembly (GAMA): $\mathbf{z}\sim 0$ Galaxy Luminosity Function down to $\mathbf{L}\sim 10^6{\mathbf{L}}_{\odot }$ via Clustering Based Redshift Inference

Abstract

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 $L\sim 10^{11.5}$ to $10^6{\mathrm{L}}_{\odot }$. 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: $m_r\lesssim 23$; 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 parametrisation with an adaptive normalisation 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 $\hat{I}\pm \approx -1.2$ for $-17\lesssim M_r\lesssim -13$, and then appears to steepen sharply for $-13\lesssim M_r\lesssim -10$. 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 $z\sim 0$ field galaxy population from the most luminous galaxies down to the GC scale.

21 pages, 13 figures, accepted by MNRAS