M. Gramann
Astrophysical Journal, Vol. 493, in press, and astro-ph/9709020
We investigate the power spectrum of velocity fluctuations in the universe, starting from four different measures of velocity: (1) the power spectrum of velocity fluctuations from peculiar velocities of galaxies; (2) the rms peculiar velocity of galaxy clusters; (3) the power spectrum of velocity fluctuations from the power spectrum of density fluctuations in the galaxy distribution; (4) and the bulk velocity from peculiar velocities of galaxies. We show that measures (1) and (2) are not consistent with each other and either the power spectrum from peculiar velocities of galaxies is overestimated or the rms cluster peculiar velocity is underestimated. The amplitude of velocity fluctuations derived from the galaxy distribution (measure 3) depends on the parameter beta. We estimate the parameter beta on the basis of measures (2) and (4). The velocity dispersion of galaxy systems originates mostly from the large-scale velocity fluctuations with wavelengths lambda >100h(-1) Mpc.
The complete paper (postscript version) is available at babbage.sissa.it
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