Probing early modification of gravity with Planck, ACT and SPT

Abstract

We consider a model of early modified gravity (EMG) that was recently proposed as a candidate to resolve the Hubble tension. The model consists of a scalar fieldσwith a nonminimal coupling (NMC) to the Ricci curvature of the formF(σ) = Mpl2+ξσ2and an effective mass induced by a quartic potentialV(σ) = λσ4/4. We present the first analyses of the EMG model in light of the latest ACT DR4 and SPT-3G data in combination with fullPlanckdata, and find a ≳ 2σ preference for a non-zero EMG contribution from a combination of primary CMB data alone, mostly driven by ACT-DR4 data. This is different from popular `Early Dark Energy' models, which are detected only when the high-ℓ information fromPlancktemperature is removed. We find that the NMC plays a key role in controlling the evolution of density perturbations that is favored by the data over the minimally coupled case. Including measurements of supernovae luminosity distance from Pantheon+, baryonic acoustic oscillations and growth factor from BOSS, and CMB lensing ofPlanckleaves the preference unaffected. In the EMG model, the tension with SH0ES is alleviated from ∼ 6σto ∼ 3σ. Further adding SH0ES data raises the detection of the EMG model above 5σ.

Review of Hubble tension solutions with new SH0ES and SPT-3G data

“…[5] also performed additional tests with data from ACT-DR4 and concluded that it did not impact significantly the main conclusions, except for EDE. Indeed, it was shown in previous works [71][72][73] that there is a preference for EDE from ACT-DR4 data. We will return to this point in section 5.…”

“…Compared to previous studies [4,5], our work contains three new features. Firstly, we included more recent data sets, like CMB temperature and polarization data from SPT-3G 2018 TT/ TE/EE [72,73], additional BAO data from eBOSS DR16 [17], and updated SH0ES data [25]. In particular, the scenarios considered in this work had not been confronted before to the new SPT-3G JCAP04(2024)059 data -except for EDE, see [72,73,110].…”

“…Firstly, we included more recent data sets, like CMB temperature and polarization data from SPT-3G 2018 TT/ TE/EE [72,73], additional BAO data from eBOSS DR16 [17], and updated SH0ES data [25]. In particular, the scenarios considered in this work had not been confronted before to the new SPT-3G JCAP04(2024)059 data -except for EDE, see [72,73,110]. Secondly, we studied the effect of curvature, extra relativistic relics, dynamical dark energy, or a time-varying electron mass in the framework of a baseline ΛCDM+Σm ν scenario with arbitrary neutrino mass, while previous works fixed the total mass to its minimum allowed value (Σm ν = 0.06 eV), which is arbitrary.…”

“…Many additional interesting models have been proposed to reduce the Hubble tension. These include Early Modified Gravity [109], New Early Dark Energy [103], other types of EDE [72,110,111], Stepped Dark Radiation [112,113], Interacting Dark Energy [114], Primordial Magnetic Fields [115,116] and many others. Due to finite computational resources, we could not include these models in this analysis, but we will investigate them in future works.…”

Special Issue on Modified Gravity Approaches to the Tensions of ΛCDM: Goals and Highlights

“…These theories, which range from scalar-tensor theories to more exotic formulations such as f (R, T) gravity and non-metricity gravity, propose alterations or extensions to GR that can naturally account for the accelerated expansion of the Universe without resorting to the cosmological constant or elucidating the dynamics of cosmic structure formation in novel ways. Their appeal lies not only in their ability to address the existing tensions [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] but also in their potential to enrich our theoretical landscape with new physics that could resolve longstanding puzzles in cosmology [58][59][60][61][62][63][64][65][66][67][68].…”