Robustness of baryon acoustic oscillation constraints for early-Universe modifications of Λ CDM cosmology

Baryon acoustic oscillations (BAO) provide a robust standard ruler and can be used to constrain the expansion history of the Universe at low redshift. Standard BAO analyses return a model-independent measurement of the expansion rate and the comoving angular diameter distance as a function of redshi...

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Bibliographic Details
Published in:Physical review. D 2020-12, Vol.102 (12), Article 123515
Main Authors: Bernal, José Luis, Smith, Tristan L., Boddy, Kimberly K., Kamionkowski, Marc
Format: Article
Language:English
Subjects:
Astronomical models
Baryons
Cosmic microwave background
Cosmology
Dark energy
Dark matter
Diameters
Neutrinos
Power spectra
Red shift
Robustness
Universe
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Summary:Baryon acoustic oscillations (BAO) provide a robust standard ruler and can be used to constrain the expansion history of the Universe at low redshift. Standard BAO analyses return a model-independent measurement of the expansion rate and the comoving angular diameter distance as a function of redshift, normalized by the sound horizon at radiation drag. However, this methodology relies on anisotropic distance distortions of a fixed, precomputed template (obtained in a given fiducial cosmology) in order to fit the observations. Therefore, it may be possible that extensions to the consensus Λ CDM add contributions to the BAO feature that cannot be captured by the template fitting. We perform mock BAO fits to power spectra computed assuming cosmological models that modify the growth of perturbations prior to recombination in order to test the robustness of the standard BAO analysis. We find no significant bias in the BAO analysis for the models under study (Λ CDM with a free effective number of relativistic species, early dark energy, and a model with interactions between neutrinos and a fraction of the dark matter), even for cases that do not provide a good fit to Planck measurements of the cosmic microwave background power spectra. This result supports the use of the standard BAO analysis and its measurements to perform cosmological parameter inference and to constrain exotic models. In addition, we provide a methodology to reproduce our study for different models and surveys, as well as discuss different options to handle eventual biases in the BAO measurements.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.102.123515