Measurement of the B-band Galaxy Luminosity Function with Approximate Bayesian Computation

In our recent paper Tortorelli et al. 2020 (arXiv: 2001.07727), we presented the first measurement in literature of galaxy population properties using the Approximate Bayesian Computation (ABC), specifically the B-band Galaxy Luminosity function. The novel methodology we developed that combines forward-modeling and ABC offers excellent prospects to robustly measure galaxy population properties as a function of redshift in large wide-field galaxy surveys, such as LSST and NGRST. The methodology has the advantage of overcoming part of the limitations that arise in wide-field galaxy studies, such as incorrect redshift estimation or separation of galaxies into red and blue. We forward model wide-field broad-band galaxy surveys using the fast image simulator UFig.  We use ABC to constrain the galaxy population model parameters of the simulations and match data from the CFHTLS. We define a number of distance metrics between the simulated and the survey data. By exploring the parameter space of the galaxy population model through ABC to find the set of parameters that minimize these distance metrics, we obtain constraints on the LFs of blue and red galaxies as a function of redshift. We compare our results to other measurements, finding good agreement at all redshifts, for both blue and red galaxies. We also compare the redshift distribution we obtain applying the same cuts as the VIPERS survey on our image simulations, finding good agreement with survey data.