Testing Λ CDM at the lowest redshifts with SN Ia and galaxy velocities


Journal Article

© 2017 IOP Publishing Ltd and Sissa Medialab srl. Peculiar velocities of objects in the nearby universe are correlated due to the gravitational pull of large-scale structure. By measuring these velocities, we have a unique opportunity to test the cosmological model at the lowest redshifts. We perform this test, using current data to constrain the amplitude of the ''signal'' covariance matrix describing the velocities and their correlations. We consider a new, well-calibrated ''Supercal'' set of low-redshift SNe Ia as well as a set of distances derived from the fundamental plane relation of 6dFGS galaxies. Analyzing the SN and galaxy data separately, both results are consistent with the peculiar velocity signal of our fiducial ΛCDM model, ruling out the noise-only model with zero peculiar velocities at greater than 7σ (SNe) and 8σ (galaxies). When the two data sets are combined appropriately, the precision of the test increases slightly, resulting in a constraint on the signal amplitude of A = 1.05-0.21+0.25, where A = 1 corresponds to our fiducial model. Equivalently, we report an 11% measurement of the product of the growth rate and amplitude of mass fluctuations evaluated at zeff = 0.02, f σ8 = 0.428-0.045+0.048, valid for our fiducial ΛCDM model. We explore the robustness of the results to a number of conceivable variations in the analysis and find that individual variations shift the preferred signal amplitude by less than ∼0.5σ. We briefly discuss our Supercal SN Ia results in comparison with our previous results using the JLA compilation.

Full Text

Duke Authors

Cited Authors

  • Huterer, D; Shafer, DL; Scolnic, DM; Schmidt, F

Published Date

  • May 5, 2017

Published In

Volume / Issue

  • 2017 / 5

Electronic International Standard Serial Number (EISSN)

  • 1475-7516

Digital Object Identifier (DOI)

  • 10.1088/1475-7516/2017/05/015

Citation Source

  • Scopus