Â« Redshift space distortions: beyond the Kaiser formula Â» |
Vincent Desjacques |
Galaxies peculiar velocities induce anisotropies in galaxy clustering - known as redshift space distortions (RSD) - that can be used to measure the growth rate of structures as a function of scale and redshift. Given the high precision of upcoming large scale surveys, accurate theoretical predictions will be essential for the interpretation of future RSD measurements. In this regard, an important and highly debated issue is the scale-dependence of galaxy âias.`In"this talk, I will show that the well-known Kaiser relation (Kaiser 1987) acquires scale-dependent contributions in a model where dark matter halos collapse from initial density peaks. One of the most salient predictions of the model is a linear, scale-dependent velocity bias which, if unaccounted for, could erroneously be interpreted as a signature of modified dark energy or gravity. I will discuss the time evolution of this velocity bias, explain how the usual halo-dark matter fluid approximation should be modified, present evidence for this effect from N-body simulations and discuss the implications of these findings. |
vendredi 6 juin 2014 - 11:00 AmphithÃ©Ã¢tre Henri Mineur, Institut d'Astrophysique de Paris |
Page web du sÃ©minaire / Seminar's webpage |