High Energy-Astrophysics | Galaxy cluster analysis of the SDSS Coadd data

Speaker: Marcelle Soares-Santos (Fermilab)

Galaxy cluster counts in spatial pixels and mass bins constitute a sensitive probe for Cosmology. Analyses based on this fact are part of the scientific program of experiments such as the upcoming Dark Energy Survey and have been pursued using the state of the art data. The team perform a measurement of cosmological parameters using cluster counts in the SDSS Coadd. A measurement using clusters requires galaxy photometric redshifts, cluster finding algorithms, cluster mass calibration, cosmological parameter estimation and a data set of sufficient scope. For the SDSS Coadd, photometric redshifts are obtained with a neural network algorithm. A cluster catalog from this sample of 13M galaxies covering 250 sq-degrees up to redshift ~1 is constructed using a Voronoi Tessellation cluster finder. The selection function is computed using DES mock galaxy catalogs. A weak lensing analysis provides the mass calibration of the cluster sample binned into observables. A joint likelihood method using the mean abundance and spatial distribution is used to obtain cosmological constraints.