2022/02/17 by Emily Tyhurst, Tyhurst, Emily, Hamsa Padmanabhan +3
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2202.08435
openalex publication_date 2022/02/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Untangling the connection between redshift space coordinates, a velocity measurement, and three dimensional real space coordinates, is a cosmological problem that is often modeled through a linear understanding of the velocity-position coupling. This linear information is better preserved in the Lagrangian space picture of the matter density field. Through Lagrangian space measurements, we can extract more information and make more accurate estimates of the linear growth rate of the universe. In this paper, we address the linear modelling of matter particle velocities through transfer functions, and in doing so examine to what degree the decrease in correlation with initial conditions may be contaminated by velocity-based nonlinearities. With a thorough analysis of the monopole-quadrupole ratio, we find the best-fit values for the Eulerian velocity dispersion, σp = 378.3 km/s for a Lorentzian finger-of-God damping factor and σp = 254.6 km/s for a Gaussian one. The covariance of the cosmological linear growth rate f, is estimated in the Eulerian and Lagrangian cases. Comparing Lagrangian and Eulerian, we find that the error in f improves by a factor of 3, without the need for nonlinear velocity dispersion modelling.