Probing early modification of gravity with Planck, ACT and SPT

Aug 23, 2023
26 pages
Published in:
  • JCAP 12 (2023) 017,
  • JCAP 12 (2023) 017
  • Published: Dec 12, 2023
    and
  • Published: Dec, 2023
e-Print:

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Abstract: (IOP)
We consider a model of early modified gravity (EMG) that was recently proposed as acandidate to resolve the Hubble tension. The model consists of a scalar field σ with anonminimal coupling (NMC) to the Ricci curvature of the form F(σ) = Mpl_{pl}2^{2}+ξσ2^{2} and an effective mass induced by a quartic potential V(σ) = λσ4^{4}/4. We present the first analyses of the EMG model in light of the latest ACTDR4 and SPT-3G data in combination with full Planck data, and find a ≳ 2σpreference for a non-zero EMG contribution from a combination of primary CMB data alone, mostlydriven by ACT-DR4 data. This is different from popular `Early Dark Energy' models, which aredetected only when the high-ℓ information from Planck temperature is removed. Wefind that the NMC plays a key role in controlling the evolution of density perturbations that isfavored by the data over the minimally coupled case. Including measurements of supernovaeluminosity distance from Pantheon+, baryonic acoustic oscillations and growth factor from BOSS,and CMB lensing of Planck leaves the preference unaffected. In the EMG model, the tensionwith SH0_{0}ES is alleviated from ∼ 6σ to ∼ 3σ. Further adding SH0_{0}ES dataraises the detection of the EMG model above 5σ.
Note:
  • 25 pages, 9 figures, 5 tables. Added minor corrections. v2 matches the published JCAP version. Comments welcome!
  • cosmological parameters from CMBR
  • modified gravity
  • coupling: minimal
  • density: perturbation
  • gravitation: model
  • mass: induced
  • curvature: Ricci
  • supernova: luminosity
  • coupling: nonminimal
  • baryon: oscillation: acoustic
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