Testing the equivalence principle on cosmological scales using the odd multipoles of galaxy cross-power spectrum and bispectrum
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Date
2021
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Publisher
IOP
Abstract
One of the cornerstones of general relativity is the equivalence principle. However,
the validity of the equivalence principle has only been established on solar system scales for
standard matter fields; this result cannot be assumed to hold for the non-standard matter
fields that dominate the gravitational dynamics on cosmological scales. Here we show how
the equivalence principle may be tested on cosmological scales for non-standard matter fields
using the odd multipoles of the galaxy cross-power spectrum and bispectrum. This test makes
use of the imprint on the galaxy cross-power spectrum and bispectrum by the parity-violating
general relativistic deformations of the past-light cone, and assumes that galaxies can be
treated as test particles that are made of baryons and cold dark matter. This assumption
leads to a non-zero galaxy-baryon relative velocity if the equivalence principle does not hold
between baryons and dark matter. We show that the relative velocity can be constrained to
be less than 28% of the galaxy velocity using the cross-power spectrum of the HI intensity
mapping/Hα galaxy survey and the bispectrum of the Hα galaxy survey.
Description
Keywords
gravity, modified gravity, cosmological parameters from LSS
Citation
Umeh, O., Koyama, K., & Crittenden, R. (2021). Testing the equivalence principle on cosmological scales using the odd multipoles of galaxy cross-power spectrum and bispectrum. Journal of Cosmology and Astroparticle Physics, 2021(08), 049. https://doi.org/10.1088/1475-7516/2021/08/049