Open AccessPredicting the peculiar velocities of nearby PSC z galaxies using the Least Action Principle
Author(s) -
Sharpe J.,
RowanRobinson M.,
Canavezes A.,
Saunders W.,
Branchini E.,
Efstathiou G.,
Frenk C.,
Keeble O.,
McMahon R. G.,
Maddox S.,
Oliver S. J.,
Sutherland W.,
Tadros H.,
White S. D. M.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04123.x
Subject(s) - physics , galaxy , astrophysics , hubble's law , redshift , cepheid variable , cosmic distance ladder , sky , astronomy , stars
We use the Least Action Principle to predict the peculiar velocities of PSC z galaxies inside cz=2000 km s −1 . Linear theory is used to account for tidal effects to cz=15 000 km s −1 , and we iterate galaxy positions to account for redshift distortions. As the Least Action Principle is valid beyond linear theory, we can predict reliable peculiar velocities even for very nearby galaxies (i.e., cz≤500 km s −1 ). These predicted peculiar velocities are then compared with the observed velocities of 12 galaxies with Cepheid distances. The combination of the PSC z galaxy survey (with its large sky coverage and uniform selection) with the accurate Cepheid distances makes this comparison relatively free from systematic effects. We find that galaxies are good tracers of the mass, even at small (≤10 h −1 Mpc) scales; under the assumption of no biasing, 0.25≤β≤0.75 (at 90 per cent confidence). We use the reliable predicted peculiar velocities to estimate the Hubble constant H 0 from the local volume without ‘stepping up’ the distance ladder, finding a confidence range of 65–75 km s −1 Mpc −1 (at 90 per cent confidence).