A new method to build the (inverse) distance ladder

Abstract

The cosmic distance ladder is the succession of techniques by which it is possible to determine distances to astronomical objects. Here, we present a new method to build the cosmic distance ladder, going from local astrophysical measurements to the CMB. Instead of relying on cosmography in order to model the luminosity-distance relation and calibrate supernovae with BAO, we exploit the distance-duality relation d L = (1 + z) 2 d A -valid if photon number is conserved and gravity is described by a metric theory. The advantage is that the results will not depend on the parametrization of the luminosity-distance relation: no model is adopted in order to calibrate BAO with supernovae. This method yields measurements of the Hubble constant and deceleration parameter that only use local observations. Furthermore, it can directly assess the impact of BAO observations on the strong 4-5σ tension between local and global H 0 . Using the latest supernova, BAO and CMB observations, we found a consistently low value of q 0 and strong inconsistency between angular and anisotropic BAO measurements, which are, or not, in agreement with CMB depending on the kind of analysis. We conclude that, in order to understand the reasons behind the H 0 crisis, a first step should be clarifying the tension between angular and anisotropic BAO as this will help understanding if new physics is required at the pre-recombination epoch or/and during the dark energy era.

Local determination of the Hubble constant and the deceleration parameter

“…This introduces correlations between M B and the properties of dark energy, which can explain why our cosmology-independent determination of q 0 differs from the constraint q M18 0 = −0.37 ± 0.15 obtained in [39]. Finally, a low local value of q 0 ≈ −1 was also obtained in [40], where the cosmic ladder was extended to BAO and CMB observations using the distance-duality relation instead of a high-redshift cosmographic expansion.…”

Ricci cosmology in light of astronomical data

“…In view of some recent works [83,84] it is worth to add a further comment on the "statistical" role played by the constant μ 0 in our analysis. In fact, it is well known that is contains both the Hubble constant and the zero point absolute magnitude M B , and that the uncertainty on the latter reflects into an additional (i.e.…”

“…Assuming that such information is actually included in the SNeIa data made available for cosmological purposes, authors from [83] point out that marginalization over H 0 and marginalization over M SN end in different results which should be taken into account in the context of the present Hubble tension debate, and that the latter marginalization should be preferred. In [83] the authors develop a way to include it; but we must point out that their total χ 2 always contain a prior on H 0 or on M SN .…”

Hints for a Gravitational Transition in Tully–Fisher Data

“…The Hubble tension may also be viewed as an inconsistency between the value of the standardized SnIa absolute magnitude M calibrated using Cepheids in the redshift range 0 < z < 0.01 (distance ladder calibration) and the corresponding M value calibrated using the recombination sound horizon (inverse distance ladder calibration) for 0.01 < z < z rec . Thus, a recently proposed class of approaches to the resolution of the Hubble tension involves a transition [22,23] of the standardized intrinsic SnIa luminosity L and absolute magnitude M at a redshift z t 0.01 from M = (−19.24 ± 0.037) mag for z < z t (as implied by Cepheid calibration) to M = (−19.4 ± 0.027) mag for z > z t (as implied by CMB calibration of the sound horizon at decoupling) [24]. Such a transition may occur due to a transition in the strength of the gravitational interactions G eff , which modifies the SnIa intrinsic luminosity L by changing the value of the Chandrasekhar mass.…”