Аннотация
The Universe may feature large-scale inhomogeneities beyond the standard
paradigm, implying that statistical homogeneity and isotropy may be reached
only on much larger scales than the usually assumed $\sim$100 Mpc. This means
that we are not necessarily typical observers and that the Copernican principle
could be recovered only on super-Hubble scales. Here, we do not assume the
validity of the Copernican principle and let Cosmic Microwave Background,
Baryon Acoustic Oscillations, type Ia supernovae, local $H_0$, cosmic
chronometers, Compton y-distortion and kinetic Sunyaev-Zeldovich observations
constrain the geometrical degrees of freedom of the local structure, which we
parametrize via the $Łambda$LTB model -- basically a non-linear radial
perturbation of a FLRW metric. In order to quantify if a non-Copernican
structure could explain away the Hubble tension, we pay careful attention to
computing the Hubble constant in an inhomogeneous universe, and we adopt model
selection via both the Bayes factor and the Akaike information criterion. Our
results show that, while the $Łambda$LTB model can successfully explain away
the $H_0$ tension, it is favored with respect to the $Łambda$CDM model only if
one solely considers supernovae in the redshift range that is used to fit the
Hubble constant, that is, $0.023<z<0.15$. If one considers all the supernova
sample, then the $H_0$ tension is not solved and the support for the
$Łambda$LTB model vanishes. Combined with other data sets, this solution to
the Hubble tension barely helps. Finally, we have reconstructed our local
spacetime. We have found that data are best fit by a shallow void with
$\delta_L -0.04$ and $r^out_L 300$ Mpc, which,
interestingly, lies on the border of the 95\% credible region relative to the
standard model expectation.
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