No evidence for bulk velocity from type Ia supernovae

Abstract

We revisit the effect of peculiar velocities on low-redshift type Ia supernovae. Velocities introduce an additional guaranteed source of correlations between supernova magnitudes that should be considered in all analyses of nearby supernova samples but has largely been neglected in the past. Applying a likelihood analysis to the latest compilation of nearby supernovae, we find no evidence for the presence of these correlations, although, given the significant noise, the data is also consistent with the correlations predicted for the standard $\Lambda$CDM model. We then consider the dipolar component of the velocity correlations -- the frequently studied "bulk velocity" -- and explicitly demonstrate that including the velocity correlations in the data covariance matrix is crucial for drawing correct and unambiguous conclusions about the bulk flow. In particular, current supernova data is consistent with no excess bulk flow on top of what is expected in $\Lambda$CDM and effectively captured by the covariance. We further clarify the nature of the apparent bulk flow that is inferred when the velocity covariance is ignored. We show that a significant fraction of this quantity is expected to be noise bias due to uncertainties in supernova magnitudes and not any physical peculiar motion.

20 pages, 4 figures; added references, one table, and clarifications in the text to match the published version

References in corpus (15)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results
• Spectra and Light Curves of Six Type Ia Supernovae at 0.511 < z < 1.12 and the Union2 Compilation
• Supernova Constraints and Systematic Uncertainties from the First 3 Years of the Supernova Legacy Survey
• Improved Distances to Type Ia Supernovae with Multicolor Light Curve Shapes: MLCS2k2
• The 6dF Galaxy Velocity Survey: Cosmological constraints from the velocity power spectrum
• Probing the isotropy of cosmic acceleration traced by Type Ia supernovae
• The peculiar velocity field: constraining the tilt of the Universe
• Testing the isotropy of the Universe by using the JLA compilation of type-Ia supernovae
• The Velocity Field of the Local Universe from Measurements of Type Ia Supernovae
• Probing bulk flow with nearby SNe Ia data
• The Three Faces of Omega_m: Testing Gravity with Low and High Redshift SN Ia Surveys
• On the perturbation of the luminosity distance by peculiar motions
• Galaxy Peculiar Velocities From Large-Scale Supernova Surveys as a Dark Energy Probe
• Tracing the cosmic velocity field at z ~ 0.1 from galaxy luminosities in the SDSS DR7
• Precision measurements of large scale structure with future type Ia supernova surveys

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