1996/11/13 by Avishai Dekel, David Burstein, Dekel, Avishai +3
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #Cosmology and Gravitation Theories #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9611108
18 pages, 1 figure, LaTex (fullpage.sty included), to be published in Critical Dialogues in Cosmology (proceedings of the Princeton 250th Anniversary conference, June 1996), ed. N. Turok (World Scientific)
arxiv created 1996/11/13 · openalex publication_date 1996/11/13 · arxiv updated 2009/12/01 · openalex created_date 2024/04/11 · openalex updated_date 2026/07/28
We were asked to debate the value of the cosmological mass-density parameter Omega. Is Omegam=1 in accordance with the simplest model? Is Omegam much smaller as indicated by some observations? There is conflicting evidence. We lay out the various methods for measuring Omegam, mention new developments and current estimates, and focus on prospects versus the associated difficulties. We try to shed light on the uncertainties that are responsible for the span of estimates for Omegam. We divide the methods into the following four classes: a. Global measures of the properties of space-time that constrain combinations of Omegam and the other cosmological parameters (Lambda, Ho, to). b. Virialized Systems. Nonlinear dynamics within galaxies and clusters on comoving scales 1-10 Mpc/h. c. Large-scale structure. Mildly-nonlinear gravitational dynamics of fluctuations on scales 10-100 Mpc/h, in particular cosmic flows. d. Growth rate of fluctuations from the last scattering of the CMB or from high redshift galaxies to the present. Methods (b) typically yield low values of Omegam=0.2-0.3. Methods (a) and (c) typically indicate higher values of Omegam=0.4-1.