Following the posterior with the ALHAMBRA survey

The probability distribution functions (PDFs) provided by photometric redshift codes such as BPZ are a powerful tool for galaxy evolution studies. Despite of their potential, only a few studies in the literature attempt to use the full PDFs in their analysis and we are still learning how to make the most of them. We present the latests PDF advances from the ALHAMBRA survey, focusing in the estimation of the B-band luminosity function.

We split the talk in several stages. At stage 0 we focus on the I-band photometry, stressing the importance of the photometric errors, the completeness function, and the number counts to end with the I-band posterior PDF. At stage 1 we study the galaxy redshift distribution Nz, defining physically the optimum binning that maximises the number of independent bins thanks to the dispersion of the data. We also describe how to deal with the cosmic variance that affects our measurements. At stage 2 we estimate the ALHAMBRA B-band luminosity functions (LFs) of red and blue galaxies at z < 1. Thanks to the posterior PDFs, the ALHAMBRA LFs account for the z and MB errors and their covariances. We modelled the ALHAMBRA LFs with a redshift-dependent model, minimising the selection effects and the impact of large scale structures.

26/11/2015 - 13:30
Carlos López-Sanjuan
CEFCA, Teruel