Cake Talk: Per Andersen – University of Copenhagen

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Cake Talk: Per Andersen

Per Andersen (PhD student, Dark Cosmology Centre)

Title:  Testing Cosmology with Bulk Flow Measurements

By measuring the peculiar velocities of nearby galaxies we can estimate the dipole of the local velocity field. We can test Lambda-CDM cosmology by comparing this “bulk flow” dipole term with the theoretical prediction. There is a history of conflicting results in the literature, where some claim a larger bulk flow measurement than allowed by Lambda-CDM, and others do not.

In this talk we will investigate the effects of survey geometry on the measured bulk flow magnitude, and whether these effects can resolve the tension that currently exists. This is done through subsampling of data from a cosmological simulation (HorizonRun) for a number of geometries. The spread in the measured bulk flows for each of these geometries is then determined, and the results thereof used as a recommendation for future work in the field.