2010/04/30 by H. J. de Vega, P. Salucci, N. Sánchez +1 · 73 citations
Physics and Astronomy · #Astrophysics #Cosmology #Cosmology and Gravitation Theories #Cuspy halo problem #Dark Matter and Cosmic Phenomena #Dark energy #Dark matter #Dark matter halo #Decoupling (probability) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Particle physics #Physics #Scalar field dark matter #Weakly interacting massive particles #astro-ph.CO #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1016/j.newast.2012.04.001
published in New Astronomy 17(7), 653-666 (Elsevier BV) · 17 pages, 15 figures, improved and expanded version to appear in New Astronomy
arxiv created 2012/04/10 · openalex publication_date 2012/04/10 · arxiv updated 2015/05/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We combine observed properties of galaxies as the core density and radius with the theoretical linear evolution of density fluctuations computed from first principles since the end of inflation till today. The halo radius r0 is computed in terms of cosmological parameters. The theoretical density profiles rho(r)/rho(0) have an universal shape as a function of r/r0 which reproduces the observations. We show that the linear approximation to the Boltzmann-Vlasov equation is valid for very large galaxies and correctly provides universal quantities which are common to all galaxies, as the surface density and density profile. By matching the theoretically computed surface density to its observed value we obtain (i) the decreasing of the phase-space density during the MD era (ii) the mass of the dark matter particle which turns to be between 1 and 2 keV and the decoupling temperature Td which turns to be above 100 GeV (iii) the core vs. cusp discrimination: keV dark matter particles produce cored density profiles while wimps (m ∼ 100 GeV, Td ∼ 5 GeV) produce cusped profiles at scales about 0.003 pc. These results are independent of the particle model and vary very little with the statistics of the dark matter particle. Non-universal galaxy quantities (which need to include non-linear effects as mergers and baryons) are reproduced in the linear approximation up to a factor of order one for the halo radius r0, galaxy mass Mgal, halo central density rho0 and velocity dispersion sqrt v2halo in the limiting case of large galaxies (both r0 and Mgal large). This shows the power of the linear approximation scheme: although it cannot capture the whole content of the structure formation, it correctly provides universal quantities which as well as the main non-universal galaxy properties.