It has been observed that the hint about dynamical dark energy in the Dark Energy Spectroscopic Instrument (DESI) baryon acoustic oscillation (BAO) observation might point to nonminimally coupled gravity. We report the first $3\sigma$ evidence for nonminimal coupling in a model-agnostic effective field theory (EFT) approach. In a nonparametric reconstruction approach, we detect a clear departure from the general relativity expectation of nonminimal coupling based on a combined analysis of DESI data release 2 BAO together with cosmic microwave background and type Ia supernova data. Also, it is found that current data can constrain up to the quadratic order ($n=2$) if the EFT function representing nonminimal coupling is Taylor expanded as a general function of the dark energy fraction ${\mathrm{\Omega }}_{\mathrm{DE}}$, i.e., ${\mathrm{\Omega }}^{\mathrm{EFT}}(a)={\sum }_{i=0}^n{c}_i^{\mathrm{EFT}}{\mathrm{\Omega }}_{\mathrm{DE}}^i(a)$. Our findings constitute a detection of modified-gravity effects and call for a more flexible parametrization of the EFT functions than commonly used ones in literature.

Close

PrevNext

View figure in article

• Alternative gravity theories
• Baryon acoustic oscillations
• Cosmic microwave background
• Cosmological parameters
• Dark energy
• General relativity