Hubble flow variations as a test for inhomogeneous cosmology
Abstract
Context. Backreactions from largescale inhomogeneities may provide an elegant explanation for the observed accelerated expansion of the universe without the need to introduce dark energy.
Aims: We propose a cosmological test for a specific model of inhomogeneous cosmology, called timescape cosmology. Using largescale galaxy surveys such as SDSS and 2MRS, we test the variation of expansion expected in the Λcold dark matter (ΛCDM) model versus a more generic differential expansion using our own calibrations of bounds suggested by timescape cosmology.
Methods: Our test measures the systematic variations of the Hubble flow towards distant galaxies groups as a function of the matter distribution in the lines of sight to those galaxy groups. We compare the observed systematic variation of the Hubble flow to mock catalogues from the Millennium Simulation in the case of the ΛCDM model, and a deformed version of the same simulation that exhibits more pronounced differential expansion.
Results: We perform a series of statistical tests, ranging from linear regressions to KolmogorovSmirnov tests, on the obtained data. They consistently yield results preferring ΛCDM cosmology over our approximated model of timescape cosmology.
Conclusions: Our analysis of observational data shows no evidence that the variation of expansion differs from that of the standard ΛCDM model.
Full Tables A.1 and A.2 are only available at the CDS via anonymous ftp to http://cdsarc.ustrasbg.fr (ftp://130.79.128.5) or via http://cdsarc.ustrasbg.fr/vizbin/qcat?J/A+A/622/A83
 Publication:

Astronomy and Astrophysics
 Pub Date:
 February 2019
 DOI:
 10.1051/00046361/201629174
 arXiv:
 arXiv:1811.11976
 Bibcode:
 2019A&A...622A..83S
 Keywords:

 cosmology: observations;
 dark energy;
 largescale structure of Universe;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 20 pages, 21 figures, accepted for publication in A&