Measuring the cosmological bulk flow using the peculiar velocities of supernovae
- Astrophysics, Cosmology and Gravity Centre, University of Cape Town, Rondebosch, Private Bag, 7700 (South Africa)
- HEPCOS, Department of Physics, SUNY at Buffalo, Buffalo, NY 14260-1500 (United States)
We study large-scale coherent motion in our universe using the existing Type IA supernovae data. If the recently observed bulk flow is real, then some imprint must be left on supernovae motion. We perform a Bayesian Monte Carlo Markov Chain analysis in various redshift bins and find a sharp contrast between the z < 0.05 and z > 0.05 data. The z < 0.05 data are consistent with the bulk flow in the direction (l,b) = (290{sup +39}{sub −31}°,20{sup +32}{sub −32}°) with a magnitude of v{sub bulk} = 188{sup +119}{sub −103}km/s at 68% confidence. The significance of detection (compared to the null hypothesis) is 95%. In contrast, z > 0.05 data (which contains 425 of the 557 supernovae in the Union2 data set) show no evidence for the bulk flow. While the direction of the bulk flow agrees very well with previous studies, the magnitude is significantly smaller. For example, the Kashlinsky, et al.'s original bulk flow result of v{sub bulk} > 600km/s is inconsistent with our analysis at greater than 99.7% confidence level. Furthermore, our best-fit bulk flow velocity is consistent with the expectation for the ΛCDM model, which lies inside the 68% confidence limit.
- OSTI ID:
- 22277841
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2011, Issue 04; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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