Building Mock Galaxy Catalogues to Test the Nature of Gravity


Shiferaw M, et. al. Building Mock Galaxy Catalogues to Test the Nature of Gravity. Astronomical Society Meeting Abstracts #235. 2020 :108.08.
Building Mock Galaxy Catalogues to Test the Nature of Gravity


The Theory of General Relativity (GR) is very well-tested on local Solar System scales, but tests on the largest cosmological scales have been limited by the volume and precision of existing galaxy surveys. This situation is expected to change in the coming decade with the advent of several new spectroscopic redshifts surveys like DESI and Euclid. In this project, we aim to test the nature of gravity on these scales by using cosmological simulations to construct mock galaxy catalogs that mimic surveys as closely as possible. In particular, we focus on ΛCDM and three variants of the f(R) model of modified gravity: F6, F5, F4, each of which enhance the strength of gravity relative to GR with increasing intensity. Because of the inherent nonlinearity of the f(R) model, we use large-scale numerical simulations which self-consistently evolve dark matter particles according to these modified equations of motion. Previous simulations have predicted a higher abundance of massive halos and stronger clustering in the f(R) model relative to GR; however, it is unclear as to how much these differences persist in the galaxy distribution. We transform each of the halo catalogs using the Halo Occupation Distribution model, which determines the likelihood of a halo having a certain number of galaxies based upon its mass. Automating this process allows us to compare the differences in the redshift-space clustering between f(R) and GR using galaxies as tracers. Finally, we trim these galaxy catalogues even further by applying survey realism, ensuring that the galaxy distribution in the two cosmologies is identical to the observer.

Last updated on 04/08/2020