Published November 15, 2024 | Published
Journal Article Open

Quantifying scalar field dynamics with DESI 2024 Y1 BAO measurements

  • 1. ROR icon California Institute of Technology
  • 2. ROR icon Stony Brook University
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Abstract

Quintessence scalar fields are a natural candidate for evolving dark energy. Unlike the phenomenological 𝑤0⁢𝑤𝑎 parameterization of the dark energy equation of state, they cannot accommodate the phantom regime of dark energy 𝑤⁡(𝑧) <−1, or crossings into the phantom regime. Recent baryon acoustic oscillation (BAO) measurements by the Dark Energy Spectroscopic Instrument (DESI) indicate a preference for evolving dark energy over a cosmological constant, ranging from 2.6⁢𝜎 −3.9⁢𝜎 when fitting to 𝑤0⁢𝑤𝑎, and combining the DESI BAO measurements with other cosmological probes. In this work, we directly fit three simple scalar field models to the DESI BAO data, combined with cosmic microwave background anisotropy measurements and supernova datasets. We find the best fit model to include a 2–4% kinetic scalar field energy Ωscf,k, for a canonical scalar field with a quadratic or linear potential. However, only the DESY-Y5 supernova dataset combination shows a preference for quintessence over Λ cold dark matter (CDM) at the 95% confidence level. Fitting to the supernova datasets Pantheon, Pantheon+, DES-Y5, and Union3, we show that the mild tension (𝑛𝜎 <3.4) under Λ⁢CDM emerges from a BAO preference for smaller values of fractional mass-energy density Ω𝑚 <0.29, while all supernova datasets, except for Pantheon, prefer larger values, Ω𝑚 >0.3. The tension under Λ⁢CDM remains noticeable (𝑛𝜎 <2.8), when replacing two of the DESI BAO redshift bins with effective redshifts 𝑧eff =0.51, and 𝑧eff =0.706 with comparable BOSS DR 12 BAO measurements at 𝑧eff =0.51, and 𝑧eff =0.61. Canonical scalar fields as dark energy are successful in mitigating that tension.

Copyright and License

© 2024 American Physical Society.

Acknowledgement

We sincerely thank Elisabeth Krause and Tim Eifler for providing computational resources that allowed us to complete this work on an ambitious timeline. We thank Ryan Camilleri for porting the DES-Y5 SN likelihood to cobaya, and David Rubin for providing the Union3 SN likelihood files. We also thank Antony Lewis for his incredible work porting the recent DESI and SN results to cobaya. We also thank Dillon Brout for useful discussions. K. B. thanks the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award No. DE-SC0011632, and the Walter Burke Institute for Theoretical Physics. The simulations in this paper use high-performance computing (HPC) resources supported by the University of Arizona TRIF, UITS, and RDI and maintained by the UA Research Technologies department. The authors would also like to thank the Stony Brook Research Computing and Cyberinfrastructure, and the Institute for Advanced Computational Science at Stony Brook University for access to the high-performance SeaWulf computing system, which was made possible by a 1.4M National Science Foundation Grant No. 1531492.

Funding

K. B. thanks the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award No. DE-SC0011632, and the Walter Burke Institute for Theoretical Physics. The simulations in this paper use high-performance computing (HPC) resources supported by the University of Arizona TRIF, UITS, and RDI and maintained by the UA Research Technologies department. The authors would also like to thank the Stony Brook Research Computing and Cyberinfrastructure, and the Institute for Advanced Computational Science at Stony Brook University for access to the high-performance SeaWulf computing system, which was made possible by a 1.4M National Science Foundation Grant No. 1531492.

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Additional details

Created:
November 18, 2024
Modified:
November 18, 2024