Quantifying scalar field dynamics with DESI 2024 Y1 BAO measurements

Journal Article · 14 November 2024 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.110.103524 · OSTI ID:2479606

Berghaus, Kim V.  ^[1]; Kable, Joshua A.  ^[2]; Miranda, Vivian  ^[2]

---

1. California Institute of Technology (CalTech), Pasadena, CA (United States)
2. Stony Brook University, NY (United States)

Quintessence scalar fields are a natural candidate for evolving dark energy. Unlike the phenomenological w₀⁢w_a 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 w_0⁢w_a, 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 Ω_scf,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 (n_σ < 3.4) under Λ ⁢CDM emerges from a BAO preference for smaller values of fractional mass-energy density Ω_m < 0.29, while all supernova datasets, except for Pantheon, prefer larger values, Ω_m > 0.3. The tension under Λ ⁢CDM remains noticeable (n_σ < 2.8), when replacing two of the DESI BAO redshift bins with effective redshifts z_eff = 0.51, and z_eff = 0.706 with comparable BOSS DR 12 BAO measurements at z_eff = 0.51, and z_eff = 0.61. Furthermore, canonical scalar fields as dark energy are successful in mitigating that tension.

• Research Organization: California Institute of Technology (CalTech), Pasadena, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF)
• Grant/Contract Number: SC0011632
• OSTI ID: 2479606
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 10 Vol. 110; ISSN 2470-0010
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English