Galaxy Luminosity Function of the Coma Cluster from Deep $u^{\prime }-g^{\prime }-r^{\prime }$ Wendelstein Imaging Data

Abstract

We derive the $g^{\prime }$ band galaxy luminosity function (GLF) of quenched resolved galaxies in the Coma cluster from a deep-imaging survey with $\approx 1.5\mathrm{de}{\mathrm{g}}^2$ around the cluster center. The dataset comprises deep $u^{\prime }$-, $g^{\prime }$-, and $r^{\prime }$-band data obtained with the Wendelstein Wide Field Imager on the $2.1$m Fraunhofer Wendelstein Telescope reaching median $3\ddot{I}ƒ$ surface brightness limits in 10" $\times$ 10" boxes of $(30.0{\mathrm{u}}^{\prime },29.6{\mathrm{g}}^{\prime },28.7{\mathrm{r}}^{\prime })\mathrm{mag}\mathrm{arcse}{\mathrm{c}}^{-2}$. We measure structural parameters across a large dynamic range in galaxy brightness ($-24.5g^{\prime }\mathrm{mag}⪅M⪅-11.3g^{\prime }\mathrm{mag}$), from the brightest cluster galaxy to low-luminosity dwarfs, including compact dwarf galaxies and ultra-diffuse galaxies. We automatically identify more than 6000 cluster member candidates based on their membership on the quiescent sequence in the $u^{\prime }-g^{\prime }$ versus $g^{\prime }-r^{\prime }$ color-color diagram. The structural parameters of bright galaxies are obtained via isophotal modeling, and fully automated parametric image fitting for faint ones. Injection-recovery tests and two identically analyzed reference fields provide statistical corrections for completeness and contamination, yielding a representative GLF that reliably probes the faint end and may serve as a benchmark for future studies. We report a best-fit single Schechter $g^{\prime }$ band GLF with $M^{\star }=-21.71_{-0.29}^{+0.26}{g}^{\prime }\mathrm{mag}$, ${\log }_{10}(\ddot{I}{•}^{\star }[{\mathrm{deg}}^{-2}{\mathrm{mag}}^{-1}])=1.355_{-0.079}^{+0.076}$, and a comparatively steep faint-end slope $\hat{I}\pm =-1.444_{-0.015}^{+0.015}$. A directly matched comparison with the Coma counterpart in SLOW, a constrained cosmological simulation using CDM, shows broad agreement between the GLFs down to the simulation limit of $M=-15.5g^{\prime }\mathrm{mag}$, despite a deficit of bright galaxies.

41 pages, 29 figures, submitted to ApJ