GAz: A genetic algorithm for photometric redshift estimation

Abstract

We present a new approach to the problem of estimating the redshift of galaxies from photometric data. The approach uses a genetic algorithm combined with non-linear regression to model the 2SLAQ LRG data set with SDSS DR7 photometry. The genetic algorithm explores the very large space of high order polynomials while only requiring optimization of a small number of terms. We find a σrms = 0.0408 ± 0.0006 for redshifts in the range 0.4 < z < 0.7. These results are competitive with the current state-of-the-art but can be presented simply as a polynomial which does not require the user to run any code. We demonstrate that the method generalizes well to other data sets and redshift ranges by testing it on SDSS DR11 and on simulated data. For other data sets or applications the code has been made available at https://github.com/rbrthogan/GAz.