DESI DR2 Galaxy Luminosity Functions
Abstract
We present galaxy luminosity functions (LFs) for the Dark Energy Spectroscopic Instrument (DESI) DR2 Bright Galaxy Survey (BGS) in the g,r,z, and w1 bands over 0.002<z<0.6. Our analysis uses updated k-corrections and evolutionary corrections, including new polynomial k-correction fits derived from BGS Year1 data that supersede earlier GAMA-based prescriptions. Exploiting the statistical power of DESI, we measure LFs to very faint magnitudes, reaching M_r-5log h = -10. Independent measurements from the North and South survey regions show excellent agreement around the LF knee, but the very small statistical uncertainties reveal that simple analytic forms fail to capture the full LF shape. The bright end departs from a pure exponential decline, while the faint end exhibits complex, non-power-law behaviour, including a pronounced upturn at M_r-5log h > -15, which is stronger for red galaxies than for blue. We show that our LFs are largely complete for galaxies with surface brightness mu_50<25, and that an apparent steepening fainter than -13 is driven primarily by local overdensity and fragmentation of large galaxies. A systematic North-South offset at the brightest magnitudes is traced to red galaxies and may reflect shallower North photometry underestimating extended early-type profiles, although this remains inconclusive. We therefore also provide LFs based on model-Petrosian magnitudes. Redshift-splitting reveals small but significant residuals, indicating limitations of a simple global evolutionary model. Using the redshift limits of Loveday (2011) we find excellent agreement with GAMA, with substantially reduced statistical errors. These measurements provide a precise reference for studies of environmental and population-dependent LFs and for testing galaxy formation models.
Cite
@article{arxiv.2511.01803,
title = {DESI DR2 Galaxy Luminosity Functions},
author = {Samuel G. Moore and Shaun Cole and Michael Wilson and Peder Norberg and John Moustakas and J. Aguilar and S. Ahlen and A. Anand and D. Bianchi and D. Brooks and F. J. Castander and T. Claybaugh and A. Cuceu and A. de la Macorra and Arjun Dey and Biprateep Dey and S. Ferraro and A. Font-Ribera and J. E. Forero-Romero and E. Gaztanaga and S. Gontcho A Gontcho and G. Gutierrez and H. K. Herrera-Alcantar and K. Honscheid and M. Ishak and R. Joyce and S. Juneau and R. Kehoe and T. Kisner and S. E. Koposov and A. Kremin and O. Lahav and C. Lamman and M. Landriau and L. Le Guillou and M. E. Levi and M. Lucey and J. R. Manera and A. Meisner and R. Miquel and S. Nadathur and W. J. Percival and C. Poppett and F. Prada and A. J. Ross and G. Rossi and E. Sanchez and D. Schlegel and M. Schubnell and H. Seo and J. Silber and D. Sprayberry and G. Tarlé and B. A. Weaver and R. H. Wechsler and R. Zhou and H. Zou},
journal= {arXiv preprint arXiv:2511.01803},
year = {2026}
}
Comments
Updated to match version accepted by MNRAS. Contains addtional analysis of selection and completness effects on the faint end of the LF