Heidelberg 2022 – scientific programme

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GR: Fachverband Gravitation und Relativitätstheorie

GR 6: Cosmology

GR 6.5: Talk

Tuesday, March 22, 2022, 17:35–17:55, GR-H3

Reaching precision cosmology faster with velocities — •Miguel Quartin — Institute of Theoretical Physics, Heidelberg University, Philosophenweg 16, Heidelberg — Instituto de Física, Universidade Federal do Rio de Janeiro, 21941-972, Rio de Janeiro, RJ, Brazil

We will show how standard candles such as type Ia supernovae and standard sirens can be used as tracers of both density and velocity fields, thus serving a new purpose in cosmology beyond mere distance indicators. We discuss how these new tracers can be combined with galaxy surveys, combining galaxy and supernova position and redshift data with supernova peculiar velocities, obtained through their magnitude scatter. The full method relies on a 6x2pt analysis which includes six power spectra. We proceed then to forecast the performance of future surveys like LSST and 4MOST with a Fisher Matrix analysis, adopting both a model-dependent and a model-independent approach. We compare the performance of the 6x2pt approach to the traditional one using only galaxy clustering and some recently proposed combinations of galaxy and supernovae data and quantify the possible gains by optimally extracting the linear information. We show that the 6x2pt method shrinks the uncertainty in growth of structure parameters significantly. The combined clustering and velocity data on the growth of structures has uncertainties at similar levels to those of the CMB but exhibit orthogonal degeneracies, and the combined constraints yield very large improvements in parameters both at the background and perturbation-level.