Constraining the Asymptotically Safe Cosmology: cosmic acceleration without dark energy

TL;DR

This paper tests an Asymptotically Safe cosmological model that explains cosmic acceleration without dark energy, using recent observational data, and finds it statistically comparable to the standard Lambda-CDM model.

Contribution

It provides the first comprehensive observational constraints on the Asymptotically Safe cosmology, demonstrating its viability as an alternative to dark energy models.

Findings

The model fits observational data as well as Lambda-CDM.

No extra fine-tuning or unproven energy scales are needed.

The model is statistically equivalent to the standard cosmological model.

Abstract

A recently proposed Asymptotically Safe cosmology provides an elegant mechanism towards understanding the nature of dark energy and its associated cosmic coincidence problem. The underlying idea is that the accelerated expansion of the universe can occur due to infrared quantum gravity modifications at intermediate astrophysical scales (galaxies or galaxy clusters) which produce local anti-gravity sources. In this cosmological model no extra unproven energy scales or fine-tuning are used. In this study the Asymptotically Safe model is confronted with the most recent observational data from low-redshift probes, namely measurements of the Hubble parameter, standard candles (Pantheon SnIa, Quasi-stellar objects), Baryonic Acoustic Oscillations (BAOs) and high redshift probes (CMB shift parameters). Performing an overall likelihood analysis we constrain the free parameters of the model and we test its performance against the concordance model (flat $\Lambda$CDM) utilizing a large family of information criteria. We find that the Asymptotically Safe model is statistically equivalent with $\Lambda$CDM, hence it can be seen as a viable and very efficient cosmological alternative.