RCSEDv2: analytic approximations of k-corrections for galaxies out to redshift $z=1$

TL;DR

This paper provides analytic approximations of k-corrections for galaxies up to redshift 1, enabling accurate photometric comparisons across different filters and redshifts, especially for large galaxy surveys.

Contribution

It extends previous methods by fitting cross-band k-corrections with polynomial functions, including WISE bands, for galaxies up to redshift 1, and provides a comprehensive set of correction coefficients.

Findings

Analytic approximations perform well for UV, optical, and near-infrared filters.

The method is applicable to about 4 million galaxies in RCSEDv2.

Enables processing of photometric data for galaxies up to redshift 1.

Abstract

To compare photometric properties of galaxies at different redshifts, we need to correct fluxes for the change of effective rest-frame wavelengths of filter bandpasses, called $k$-corrections. At redshifts $z>0.3$, the wavelength shift becomes so large that typical broadband photometric bands shift into the neighboring rest frame band. At $z=0.6-0.8$ the shift reaches two or even three bands. Therefore, we need perform $k$-corrections from one observed bandpass to another. Here we expand the methodology proposed by Chilingarian et al. (2010) and fit cross-band $k$-corrections by smooth low-order polynomial functions of one observed color and a redshift - this approach but without cross-band is implemented as standard functions in {\sc topcat}, which can be used for galaxies at $z<0.5$. We also computed analytic approximations for WISE bands, which were not available in the past. We now have a complete set of $k$-corrections coefficients, which allow us to process photometric measurements for galaxies out to redshift $z=1$. We calculated standard and cross-band $k$-corrections for about 4 million galaxies in second Reference Catalog of Spectral Energy Distributions (RCSEDv2) of galaxies and we showed that, in cases of widely used UV, optical and near-infrared filters, our analytic approximations work very well and can be used for extragalactic data from future wide-field surveys.