Reconstructing the velocity field beyond the local universe

R. Johnston, David James Bacon, Luis F. A. Teodoro, Robert Nichol, M. S. Warren, Catherine M. Cress

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We present a maximum probability approach to reconstructing spatial maps of the peculiar velocity field at redshifts z∼0.1, where the velocities have been measured from distance indicators (DI) such as Dn−σ relations or Tully–Fisher. With the large statistical uncertainties associated with DIs, our reconstruction method aims to recover the underlying true peculiar velocity field by reducing these errors with the use of two physically motivated filtering prior terms. The first constructs an estimate of the velocity field derived from the galaxy over-density δg and the second makes use of the matter linear density power spectrum Pk. Using N-body simulations we find, with an SDSS-like sample (Ngal≃33 per deg2), an average correlation coefficient value of r=0.55±0.02 between our reconstructed velocity field and that of the true velocity field from the simulation. However, with a suitably high number density of galaxies from the next generation surveys (e.g. Ngal≃140 per deg2) we can achieve an average r=0.70±0.02 out to moderate redshifts z∼0.1. This will prove useful for future tests of gravity, as these relatively deep maps are complementary to weak lensing maps at the same redshift.
Original languageEnglish
Article number1812
Pages (from-to)1812
JournalGeneral Relativity and Gravitation
Issue number11
Publication statusPublished - Oct 2014


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