Universe Colloquium: Statistical detection of halos in galaxy surveys

by Alexander Merson (University College London)

Wednesday 15 Jul 2015, 16:30 → 17:30 Europe/Berlin

seminar room (Excellence Cluster Universe, Boltzmannstrasse 2, Garching)

Alex will discuss recent work to present a novel Bayesian methodology for detecting halos of different masses in galaxy survey observations, whilst jointly quantifying the corresponding uncertainties. This methodology first uses the previously published HADES algorithm to create an ensemble of realisations of the matter density field throughout the survey volume. Using an N-body simulation to relate the density field to halo mass, we then use a Bayesian chain rule to build up maps of the detection probability of halos about specific mass thresholds. Demonstration of the methodology using a realistic galaxy mock catalogue shows an excellent agreement between the peaks in the probability maps and the positions of the dark matter halos. We conclude that this method is a promising novel tool for analysing observations of the large-scale cosmic web. The Universe Colloquium is followed by a social gathering with wine and cheese.