The first analytical expression to estimate photometric redshifts suggested by a machine

Krone-Martins, A. and Ishida, E. E. O. and De Souza, Rafael da Silva (2014) The first analytical expression to estimate photometric redshifts suggested by a machine. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 443 (1). L34-L38. ISSN 0035-8711

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Abstract

We report the first analytical expression purely constructed by a machine to determine pho- tometric redshifts (zphot) of galaxies. A simple and reliable functional form is derived using 41, 214 galaxies from the Sloan Digital Sky Survey Data Release 10 (SDSS-DR10) spectro- scopic sample. The method automatically dropped the u and z bands, relying only on g, r and i for the final solution. Applying this expression to other 1, 417, 181 SDSS-DR10 galaxies, with measured spectroscopic redshifts (zspec), we achieved a mean 〈(zphot − zspec)/(1 + zspec)〉 . 0.0086 and a scatter σ(zphot−zspec)/(1+zspec) . 0.045 when averaged up to z . 1.0. The method was also applied to the PHAT0 dataset, confirming the competitiveness of our results when faced with other methods from the literature. This is the first use of symbolic regression in cosmology, representing a leap forward in astronomy-data-mining connection.

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