Peculiar Velocity of the Sun and its Relation to the Cosmic Microwave Background

AbstractUsing redshifts from the 2M++ redshift compilation, we reconstruct the density of galaxies within 200 h−1 Mpc, and compare the predicted peculiar velocities Tully-Fisher and SNe peculiar velocities. The comparison yields a best-fit value of β ≡ Ωm0.55/b* = 0.431 ± 0.021, suggesting Ωm0.55σ8,lin = 0.401 ± 0.024, in good agreement with other probes. The predicted peculiar velocity of the Local Group from sources within the 2M++ volume is 540 ± 40 km s−1, towards l = 268° ± 4°, b = 38° ± 6°, which is misaligned by only 10° with the Cosmic Microwave Background dipole. To account for sources outside the 2M++ volume, we fit simultaneously for β* and an external bulk flow in our analysis. The external bulk flow has a velocity of 159 ± 23 km s−1 towards l = 304° ± 11°, b6° ± 13°.

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The Distance of the Virgo Cluster

Highlights of Astronomy ◽

10.1017/s1539299600005190 ◽

1983 ◽

Vol 6 ◽

pp. 227-239

Author(s):

David A. Hanes

Keyword(s):

Cosmic Microwave Background ◽

Velocity Component ◽

Local Group ◽

Virgo Cluster ◽

Microwave Background ◽

Global Expansion ◽

Peculiar Velocity ◽

Rosetta Stone ◽

Extragalactic Distance Scale ◽

Simple Picture

Until the discovery (Corey & Wilkinson, 1976) of the anisotropy of the cosmic microwave background, the Virgo cluster represented something like a Rosetta Stone for many observational cosmologists: in the absence of a significant peculiar velocity component for the Local Group in the direction of the Virgo cluster, its distance, accurately measured, might reveal the global expansion rate and the Hubble age. Although this simple picture has changed, the distance of the Virgo cluster remains important, partly for a sharper understanding of the properties of rich clusters and the galaxies they contain, but more importantly (for my purposes here) as an interesting distance over which we may test various constructions of the extragalactic distance scale.

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Scale-invariant density perturbations, anisotropy of the cosmic microwave background, and large-scale peculiar velocity field

The Astrophysical Journal ◽

10.1086/184479 ◽

1985 ◽

Vol 293 ◽

pp. L1 ◽

Cited By ~ 23

Author(s):

N. Vittorio ◽

J. Silk

Keyword(s):

Velocity Field ◽

Cosmic Microwave Background ◽

Large Scale ◽

Invariant Density ◽

Microwave Background ◽

Scale Invariant ◽

Peculiar Velocity ◽

Density Perturbations

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Constraints on Cosmological Models from Cosmic Flows

Symposium - International Astronomical Union ◽

10.1017/s0074180900216720 ◽

2005 ◽

Vol 201 ◽

pp. 471-472

Author(s):

Michael J. Hudson ◽

Russell J. Smith ◽

John R. Lucey ◽

David J. Schlegel ◽

Roger L. Davies

Keyword(s):

Cosmic Microwave Background ◽

Measurement Errors ◽

Cosmological Models ◽

Bulk Velocity ◽

Microwave Background ◽

Peculiar Velocity ◽

Cluster Sample ◽

Large Bulk

The SMAC cluster sample (Hudson et al. 1999), with a depth of ˜ 12000km s-1, has a bulk velocity of ˜ 600 km s-1, with respect to the Cosmic Microwave Background (CMB) frame. Other surveys (Willick 1999, hereafter LP10k; Lauer & Postman 1994, hereafter ACIF) have also yielded large bulk motions on similarly large scales. Taken at face value, these results appear to be in conflict with bulk flows expected from favoured cosmological models. However, at the same time, other surveys (notably Dale et al. 1999, hereafter SC) have found rather small bulk motions on large scales. We have measured bulk flows from the above mentioned surveys plus SNIa (Riess et al. 1995) in a consistent way. The results are given in Table 1. The measurement errors are due to peculiar velocity errors. Note that these are the errors typically quoted. Based on these errors alone, there appears to be conflict between some of the surveys (e.g. SC vs SMAC).

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