Constraints on Cosmology and Gravity from the Dynamics of Voids
Abstract
The Universe is mostly composed of large and relatively empty domains known as cosmic voids, whereas its matter content is predominantly distributed along their boundaries. The remaining material inside them, either dark or luminous matter, is attracted to these boundaries and causes voids to expand faster and to grow emptier over time. Using the distribution of galaxies centered on voids identified in the Sloan Digital Sky Survey and adopting minimal assumptions on the statistical motion of these galaxies, we constrain the average matter content Ω_{m}=0.281 ±0.031 in the Universe today, as well as the linear growth rate of structure f /b =0.417 ±0.089 at median redshift z ¯=0.57 , where b is the galaxy bias (68% C.L.). These values originate from a percentlevel measurement of the anisotropic distortion in the voidgalaxy crosscorrelation function, ɛ =1.003 ±0.012 , and are robust to consistency tests with bootstraps of the data and simulated mock catalogs within an additional systematic uncertainty of half that size. They surpass (and are complementary to) existing constraints by unlocking cosmological information on smaller scales through an accurate model of nonlinear clustering and dynamics in void environments. As such, our analysis furnishes a powerful probe of deviations from Einstein's general relativity in the lowdensity regime which has largely remained untested so far. We find no evidence for such deviations in the data at hand.
 Publication:

Physical Review Letters
 Pub Date:
 August 2016
 DOI:
 10.1103/PhysRevLett.117.091302
 arXiv:
 arXiv:1602.01784
 Bibcode:
 2016PhRvL.117i1302H
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 11 pages, 7 figures. Reflects published version in PRL including Supplemental Material