Compression and Classification Methods for Galaxy Spectra in Large Redshift Surveys

Abstract

Methods for compression and classification of galaxy spectra, which are useful for large galaxy redshift surveys (such as the SDSS, 2dF, 6dF and VIRMOS), are reviewed. In particular, we describe and contrast three methods: (i) Principal Component Analysis, (ii) Information Bottleneck, and (iii) Fisher Matrix. We show applications to 2dF galaxy spectra and to mock semi-analytic spectra, and we discuss how these methods can be used to study physical processes of galaxy formation, clustering and galaxy biasing in the new large redshift surveys.