scholarly journals The Distance of the Virgo Cluster

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.

scholarly journals Cosmological parameters from the comparison of peculiar velocities with predictions from the 2M++ density field

2014 ◽  
Vol 11 (S308) ◽  
pp. 318-321
Author(s):  
Michael J. Hudson ◽  
Jonathan Carrick ◽  
Stephen J. Turnbull ◽  
Guilhem Lavaux
Keyword(s):  
Cosmic Microwave Background ◽  
Local Group ◽  
Cosmological Parameters ◽  
Density Field ◽  
Bulk Flow ◽  
Microwave Background ◽  
Peculiar Velocity ◽  
Peculiar Velocities ◽  
Best Fit ◽  
Good Agreement

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°.

scholarly journals Void asymmetries in the cosmic web: a mechanism for bulk flows

2014 ◽  
Vol 11 (S308) ◽  
pp. 561-570
Author(s):  
J. Bland-Hawthorn ◽  
S. Sharma
Keyword(s):  
Dark Matter ◽  
Cosmic Microwave Background ◽  
Large Scale ◽  
Local Group ◽  
3D Structure ◽  
Moving Frame ◽  
Microwave Background ◽  
Local Universe ◽  
Scale Separation

AbstractBulk flows of galaxies moving with respect to the cosmic microwave background are well established observationally and seen in the most recent ΛCDM simulations. With the aid of an idealised Gadget-2 simulation, we show that void asymmetries in the cosmic web can exacerbate local bulk flows of galaxies. The {\it Cosmicflows-2} survey, which has mapped in detail the 3D structure of the Local Universe, reveals that the Local Group resides in a “local sheet” of galaxies that borders a “local void” with a diameter of about 40 Mpc. The void is emptying out at a rate of 16 km s-1Mpc-1. In a co-moving frame, the Local Sheet is found to be moving away from the Local Void at ∼ 260 km s-1. Our model shows how asymmetric collapse due to unbalanced voids on either side of a developing sheet or wall can lead to a systematic movement of the sheet. We conjectured that asymmetries could lead to a large-scale separation of dark matter and baryons, thereby driving a dependence of galaxy properties with environment, but we do {\it not} find any evidence for this effect.

scholarly journals The Peculiar Velocity of the Local Group in the Direction of the Virgo Cluster

1987 ◽  
Vol 117 ◽  
pp. 115-115
Author(s):  
L. Staveley-Smith ◽  
R. D. Davies
Keyword(s):  
Local Group ◽  
Hubble Constant ◽  
Virgo Cluster ◽  
Density Parameter ◽  
Field Observations ◽  
Peculiar Velocity ◽  
Peculiar Velocities ◽  
Scaling Methods ◽  
Crucial Test ◽  
Local Value

The measurement of the amplitude of the Local Group infall velocity towards the Virgo Cluster is a crucial test for the value of the universal density parameter Ωo and the ratio of the universal Hubble constant to its local value. However, a very large discrepancy exists between total infall velocities derived from peculiar velocity field observations and those derived from “scaling” methods using standard candles in the Virgo and Coma clusters. The former have tended to produce high Virgocentric peculiar velocities (350 to 500 km s−1) whilst the latter give much lower values (-70 to 100 km s−1).

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

Nature ◽  
1967 ◽  
Vol 216 (5117) ◽  
pp. 748-753 ◽  
Author(s):  
J. M. STEWART ◽  
D. W. SCIAMA
Keyword(s):  
Cosmic Microwave Background ◽  
The Sun ◽  
Microwave Background ◽  
Peculiar Velocity

scholarly journals Asteroseismology, standard candles and the Hubble Constant: what is the role of asteroseismology in the era of precision cosmology?

2013 ◽  
Vol 9 (S301) ◽  
pp. 233-240
Author(s):  
Hilding R. Neilson ◽  
Marek Biesiada ◽  
Nancy Remage Evans ◽  
Marcella Marconi ◽  
Chow-Choong Ngeow ◽  
...  
Keyword(s):  
Cosmic Microwave Background ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Variable Stars ◽  
Distance Scale ◽  
Microwave Background ◽  
Classical Cepheids ◽  
Modern Cosmology ◽  
Extragalactic Distance Scale

AbstractClassical Cepheids form one of the foundations of modern cosmology and the extragalactic distance scale; however, cosmic microwave background observations measure cosmological parameters and indirectly the Hubble Constant, H0, to unparalleled precision. The coming decade will provide opportunities to measure H0 to 2% uncertainty thanks to the Gaia satellite, JWST, ELTs and other telescopes using Cepheids and other standard candles. In this work, we discuss the upcoming role for variable stars and asteroseismology in calibrating the distance scale and measuring H0 and what problems exist in understanding these stars that will feed back on these measurements.

Constraints on Cosmological Models from Cosmic Flows

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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