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Model-independent constraints on Ωm and H(z) from the link between geometry and growth

Abstract:

We constrain the expansion history of the Universe and the cosmological matter density fraction in a model-independent way by exclusively making use of the relationship between background and perturbations under a minimal set of assumptions. We do so by employing a Gaussian process to model the expansion history of the Universe from present time to the recombination era. The expansion history and the cosmological matter density are then constrained using recent measurements from cosmic chronometers, Type-Ia supernovae, baryon acoustic oscillations, and redshift-space distortion data. Our results show that the evolution in the reconstructed expansion history is compatible with the Planck 2018 prediction at all redshifts. The current data considered in this study can constrain a Gaussian process on H(z) to an average 9.4 per cent precision across redshift. We find Ωm = 0.224 ± 0.066, lower but statistically compatible with the Planck 2018 cosmology. Finally, the combination of future DESI measurements with the CMB measurement considered in this work holds the promise of 8 per cent average constraints on a model-independent expansion history as well as a five-fold tighter Ωm constraint using the methodology developed in this work.

Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1093/mnras/stac431

Authors


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Institution:
University of Oxford
Role:
Author
More by this author
Institution:
University of Oxford
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Astrophysics
Oxford college:
St Peter's College
Role:
Author
ORCID:
0000-0002-4598-9719
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Astrophysics
Oxford college:
Oriel College
Role:
Author
ORCID:
0000-0002-3021-2851


Publisher:
Oxford University Press
Journal:
Monthly Notices of the Royal Astronomical Society More from this journal
Volume:
512
Issue:
2
Pages:
1967-1984
Publication date:
2022-02-17
Acceptance date:
2022-02-14
DOI:
EISSN:
1365-2966
ISSN:
0035-8711


Language:
English
Keywords:
Pubs id:
1255277
Local pid:
pubs:1255277
Deposit date:
2023-01-04

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