2016MNRAS.457.3285M -
Mon. Not. R. Astron. Soc., 457, 3285-3305 (2016/April-2)
Defining the frame of minimum non-linear Hubble expansion variation.
McKAY J.H. and WILTSHIRE D.L.
Abstract (from CDS):
We characterize a cosmic rest frame in which the monopole variation of the spherically averaged non-linear Hubble expansion is most uniform, under arbitrary local Lorentz boosts of the central observer. Using the COMPOSITE sample of 4534 galaxies, we identify a degenerate set of candidate minimum non-linear variation frames, which includes the rest frame of the Local Group (LG) of galaxies, but excludes the standard cosmic microwave background (CMB) frame. Candidate rest frames defined by a boost from the LG frame close to the plane of the galaxy have a statistical likelihood similar to the LG frame. This may result from a lack of constraining data in the Zone of Avoidance. We extend our analysis to the Cosmicflows-2 (CF2) sample of 8162 galaxies. While the signature of a systematic boost offset between the CMB and LG frame averages is still detected, the spherically averaged non-linear expansion variation in all rest frames is significantly larger in the CF2 sample than would be reasonably expected. We trace this to the CF2 distances being reported without a correction for inhomogeneous distribution Malmquist bias. Systematic differences in the inclusion of the large SFI++ subsample into the COMPOSITE and CF2 catalogues are analysed. Our results highlight the importance of a careful treatment of Malmquist biases for future peculiar velocities studies, including tests of the hypothesis of Wiltshire et al. that a significant fraction of the CMB temperature dipole may be non-kinematic in origin.
Abstract Copyright:
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
cosmology: observations - cosmology: theory - distance scale
Errata:
erratum vol. 463, p. 3113 (2016)
Simbad objects:
2
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