Open AccessNeutrinos as cluster dark matter
Author(s) -
Sanders R. H.
Publication year - 2007
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 - 10.1111/j.1365-2966.2007.12073.x
Subject(s) - physics , astrophysics , dark matter , neutrino , galaxy cluster , baryon , modified newtonian dynamics , galaxy , hydrostatic equilibrium , cold dark matter , cooling flow , galaxy formation and evolution , galaxy rotation curve , particle physics , astronomy
The dynamical mass of clusters of galaxies, calculated in terms of MOdified Newtonian Dynamics (MOND), is a factor of 2 or 3 times smaller than the Newtonian dynamical mass but remains significantly larger than the observed baryonic mass in the form of hot gas and stars in galaxies. Here I consider further the suggestion that the undetected matter might be in the form of cosmological neutrinos with mass of the order of 2 eV. If the neutrinos and baryons have comparable velocity dispersions and if the two components maintain their cosmological density ratio, then the electron density in the cores of clusters should be proportional to T 3/2 , as appears to be true in non‐cooling flow clusters. This is equivalent to the ‘entropy floor’ proposed to explain the steepness of the observed luminosity–temperature relation, but here preheating of the medium is not required. Two‐fluid (neutrino–baryon) hydrostatic models of clusters, in the context of MOND, reproduce the observed luminosity–temperature relation of clusters. If the β law is imposed on the gas density distribution, then the self‐consistent models predict the general form of the observed temperature profile in both cooling and non‐cooling flow clusters.