Open AccessCosmic momentum field and mass fluctuation power spectrum
Author(s) -
Park Changbom
Publication year - 2000
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.1365-8711.2000.03886.x
Subject(s) - physics , scalar field , field (mathematics) , quantum electrodynamics , spectral density , momentum (technical analysis) , astrophysics , peculiar velocity , vector field , galaxy , computational physics , classical mechanics , mechanics , redshift , statistics , mathematics , finance , pure mathematics , economics
We introduce the cosmic momentum field as a new measure of the large‐scale peculiar velocity and matter fluctuation fields. The momentum field is defined as the peculiar velocity field traced and weighted by galaxies, and is equal to the velocity field in the linear regime. We show that the radial component of the momentum field can be considered as a scalar field with the power spectrum which is practically one‐third of that of the total momentum field. We present a formula for the power spectrum directly calculable from the observed radial peculiar velocity data. The momentum power spectrum is measured for the MAT sample in the Mark III catalogue of peculiar velocities of galaxies. Using the momentum power spectrum we find the amplitude of the matter power spectrum is and at the wavenumbers 0.049 and 0.074 h Mpc −1 , respectively, where Ω is the density parameter. The 68 per cent confidence limits include the cosmic variance. The measured momentum and density power spectra together indicate that the parameter or where b O is the bias factor for optical galaxies.