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--5$\sigma$ 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.
Description
A new method to build the (inverse) distance ladder
Links and resources
Tags