Cosmological data and indications for new physics

Abstract

Data from the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT), combined with the nine-year data release from the WMAP satellite, provide very precise measurements of the cosmic microwave background (CMB) angular anisotropies down to very small angular scales. Augmented with measurements from Baryonic Acoustic Oscillations surveys and determinations of the Hubble constant, we investigate whether there are indications for new physics beyond a Harrison-Zel'dovich model for primordial perturbations and the standard number of relativistic degrees of freedom at primordial recombination. All combinations of datasets point to physics beyond the minimal Harrison-Zel'dovich model in the form of either a scalar spectral index different from unity or additional relativistic degrees of freedom at recombination (e.g., additional light neutrinos). Beyond that, the extended datasets including either ACT or SPT provide very different indications: while the extended-ACT (eACT) dataset is perfectly consistent with the predictions of standard slow-roll inflation, the extended-SPT (eSPT) dataset prefers a non-power-law scalar spectral index with a very large variation with scale of the spectral index. Both eACT and eSPT favor additional light degrees of freedom. eACT is consistent with zero neutrino masses, while eSPT favors nonzero neutrino masses at more than 95% confidence.

13 pages, 5 figures, 2 tables

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Cited by in corpus (8)

• Implication of the Hubble tension for the primordial Universe in light of recent cosmological data
• Towards early dark energy and $n_s$=1 with Planck, ACT and SPT
• The $H_0$ and ${\sigma }_8$ tensions and the scale invariant spectrum
• Bayesian Evidence against Harrison-Zel'dovich spectrum in tension cosmology
• Do joint CMB and HST data support a scale invariant spectrum?
• A Bayesian analysis of inflationary primordial spectrum models using Planck data
• Testing scale-invariant inflation against cosmological data
• One Extension to Explain Them All, One Scale-Invariant Spectrum to Test Them All, and in One Model Bind Them