Testing Homogeneity with Galaxy Star Formation Histories

Abstract

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 lightcone, while observations take place on the lightcone. 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 0.04Gpc3. Using the SFH in a time period which samples the history of the Universe between look-back times 11.5 to 13.4 Gyrs 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%.

7 pages, 4 figures, improvements, clarifications, extra references, change in title; version accepted by ApJL

References in corpus (9)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The Baryon Oscillation Spectroscopic Survey of SDSS-III
• Recovering galaxy star formation and metallicity histories from spectra using VESPA
• A general test of the Copernican Principle
• The WiggleZ Dark Energy Survey: the transition to large-scale cosmic homogeneity
• A Test of the Copernican Principle
• Testing the Void against Cosmological data: fitting CMB, BAO, SN and H0
• The Cosmic Microwave Background in an Inhomogeneous Universe - why void models of dark energy are only weakly constrained by the CMB
• Reconciling the local void with the CMB

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• Cosmic Clocks
• Measuring the Homogeneity of the Universe Using Polarization Drift
• Relativistic cosmology number densities in void-Lemaitre-Tolman-Bondi models
• Evaluating backreaction with the ellipsoidal collapse model
• Cosmological model dependence of the galaxy luminosity function: far-infrared results in the Lemaitre-Tolman-Bondi model
• Is the local Hubble flow consistent with concordance cosmology?
• Fluids in cosmology
• A Test for the Zero Mean Hypothesis in Cosmology