2006/09/18 by Spyros Basilakos, Manolis Plionis · 1 citation
Physics and Astronomy · #Amplitude #Astronomy and Astrophysical Research #Astrophysics and Cosmic Phenomena #Dark matter #Dipole #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitation #Gravitational field #Local Group #Redshift #Sky #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2006.11075.x
published as Mon.Not.Roy.Astron.Soc.373:1112-1116,2006 · 7 pages, 3 figures, MNRAS in press
arxiv created 2006/09/18 · openalex publication_date 2006/11/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We re-examine the gravitational acceleration (dipole) induced on the Local Group of galaxies by the Infrared Astronomical Satellite (IRAS) galaxy distribution of the Point Source Catalog redshift (PSCz) survey. We treat the cirrus-affected low galactic latitudes by utilizing a spherical harmonic expansion of the galaxy surface density field up to the octapole order. We find strong indications for significant contributions to the Local Group motion from depths up to ∼185 h−1 Mpc and a possible contribution even from ∼210 h−1 Mpc, in agreement with the recent analysis of Kocevski & Ebeling of a whole-sky X-ray cluster survey. What changes with respect to the previous PSCz dipole analyses is: (i) the large-scale dipole contributions and (ii) an increase of the overall dipole amplitude due to the important contribution of the local volume (≲ 4 h−1 Mpc), which we now take into account. This results in a lower value of the β (≡Ω0.6m/b) parameter, which we find to be βIRAS≃ 0.49 in real space. Therefore, for the concordance cosmological model (Ωm= 1 −ΩΛ= 0.3), the IRAS galaxies bias factor is bIRAS≃ 1, which means that IRAS galaxies are good tracers of the underlying matter distribution.