A null test to probe the scale dependence of the growth of structure as a test of general relativity
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Volume
492
Pagination
L34 - L39
Publisher
DOI
10.1093/mnrasl/slz175
Journal
Monthly Notices of the Royal Astronomical Society: Letters
Issue
ISSN
1745-3925
Metadata
Show full item recordAbstract
The main science driver for the coming generation of cosmological surveys is understanding dark energy that relies on testing general relativity on the largest scales. Once we move beyond the simplest explanation for dark energy of a cosmological constant, the space of possible theories becomes both vast and extremely hard to compute realistic observables. A key discriminator of a cosmological constant, however, is that the growth of structure is scale invariant on large scales. By carefully weighting observables derived from distributions of galaxies and a dipole pattern in their apparent sizes, we construct a null test that vanishes for any model of gravity or dark energy where the growth of structure is scale independent. It relies only on very few assumptions about cosmology, and does not require any modelling of the growth of structure. We show that with a survey like the Dark Energy Spectroscopic Instrument (DESI) a scale dependence of the order of 10–20 per cent can be detected at 3σ with the null test, which will drop by a factor of 2 for a survey like the Square Kilometre Array. We also show that the null test is very insensitive to typical uncertainties in other cosmological parameters including massive neutrinos and scale-dependent bias, making this a key null test for dark energy.
Authors
Franco, FO; Bonvin, C; Clarkson, CCollections
- Physics and Astronomy [970]