Testing homegeneity with Galaxy Star formation histories
Date
2013Author
Hoyle, Ben
Jimenez, Raul
Maartens, Roy
Heavens, Alan
Clarkson, Chris
Tojeiro, Rita
Metadata
Show full item recordAbstract
Observationally confirming spatial homogeneity on sufficiently large cosmological scales is of importance to test
one of the underpinning assumptions of cosmology, and is also imperative for correctly interpreting dark energy.
A challenging aspect of this is that homogeneity must be probed inside our past light cone, while observations take
place on the light cone. The star formation history (SFH) in the galaxy fossil record provides a novel way to do this.
We calculate the SFH of stacked luminous red galaxy (LRG) spectra obtained from the Sloan Digital Sky Survey.
We divide the LRG sample into 12 equal-area contiguous sky patches and 10 redshift slices (0.2 < z < 0.5),
which correspond to 120 blocks of volume ∼0.04 Gpc3. Using the SFH in a time period that samples the history
of the universe between look-back times 11.5 and 13.4 Gyr as a proxy for homogeneity, we calculate the posterior
distribution for the excess large-scale variance due to inhomogeneity, and find that the most likely solution is no
extra variance at all. At 95% credibility, there is no evidence of deviations larger than 5.8%.