Miguel Zumalacarregui, Juan Garcia-Bellido, Pilar Ruiz-Lapuente
New constraints on inhomogeneous Lem\^aitre-Tolman-Bondi models alternative
to Dark Energy are presented, focusing on profiles with homogeneous Big Bang
and baryon fraction. The Baryon Acoustic Scale at early times is computed in
terms of the asymptotic value and then projected to different redshifts by
following the geodesics of the background metric. Additionally, a new
model-independent method to constraint the local expansion rate in terms of the
supernovae luminosity is introduced. Cosmologies described by an adiabatic GBH
profile with $\Omega_{\rm out}=1$ and $\Omega_{\rm out}\leq 1$ are investigated
using Monte Carlo Markov Chain analysis including the latest Baryon Acoustic
Oscillations (BAO) data from the WiggleZ collaboration and the local expansion
rate from the Hubble Space Telescope, together with Union-II type Ia supernovae
data and the position of the Cosmic Microwave Background peaks from WMAP. The
addition of BAO data at higher redshifts increases considerably their
constraining power and represents a new drawback for this type of models,
yielding a value of the local density parameter $\Omega_{\rm in}\gtrsim 0.2$
which is 3$\sigma$ apart from the value $\Omega_{\rm in}\lesssim 0.15$ found
using supernovae. Asymptotically flat models show an additional tension
regarding the value of the Hubble rate and the present age of the universe.
Although the $\chi^2$/d.o.f. for the GBH-LTB models is similar to that of a
fiducial $\Lambda$CDM model, a Bayesian analysis shows that a constrained GBH
model is ruled out at high confidence. The situation does not improve if the
asymptotic flatness assumption is dropped for these models. (abridged)
View original:
http://arxiv.org/abs/1201.2790
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