The 2.4 $\mu$m Galaxy Luminosity Function as Measured Using WISE. I. Measurement Techniques

TL;DR

This paper introduces a novel statistical method for measuring galaxy luminosity functions that accounts for complex color selection biases across multiple surveys, enabling more accurate galaxy population studies.

Contribution

It presents a new likelihood-based estimator using the spectro-luminosity functional and a refined parametrization of luminosity function evolution, enhancing analysis of multi-survey galaxy data.

Findings

Developed a general estimator for all color selection biases.

Proposed a new parametrization for luminosity function evolution.

Method will be applied to WISE galaxy data at 2.4 μm.

Abstract

The astronomy community has at its disposal a large back catalog of public spectroscopic galaxy redshift surveys that can be used for the measurement of luminosity functions. Utilizing the back catalog with new photometric surveys to maximum efficiency requires modeling the color selection bias imposed on selection of target galaxies by flux limits at multiple wavelengths. The likelihood derived herein can address, in principle, all possible color selection biases through the use of a generalization of the luminosity function, $\Phi(L)$, over the space of all spectra: the spectro-luminosity functional, $\Psi[L_\nu]$. It is, therefore, the first estimator capable of simultaneously analyzing multiple redshift surveys in a consistent way. We also propose a new way of parametrizing the evolution of the classic Shechter function parameters, $L_\star$ and $\phi_\star$, that improves both the physical realism and statistical performance of the model. The techniques derived in this work will be used in an upcoming paper to measure the luminosity function of galaxies at the rest frame wavelength of $2.4\operatorname{\mu m}$ using the Widefield Infrared Survey Explorer (WISE).