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The nature of dark matter

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Dark matter could light up the first stars in the universe if the dark matter is made up of weakly interacting neutrinos, right-handed neutrinos, or also called sterile neutrinos.

Qué
  • coloquio
Cuándo 20/11/2007
de 11:00 am a 12:00 pm
Dónde FCAG. Salón Meridiano
Nombre Peter L. Biermann
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Dark matter could light up the first stars in the universe if the dark matter is made up of weakly interacting neutrinos, right-handed neutrinos, or also called sterile neutrinos. We have shown that sterile neutrino decays could speed up the formation of molecular hydrogen and light up the first stars as early as 20-100 million years after the big bang. The light from these first stars could ionize the interstellar gas by 150-400 million years after the big bang, in accordance with the observations. Formation of central galactic black holes, as well as structure on subgalactic scales favor some form of warm dark matter, such as sterile neutrinos, as dark matter. The kick required to accelerate pulsars may be another key argument. The consensus of several indirect pieces of evidence leads one to believe that the long sought-after dark-matter particle may, indeed, be a sterile neutrino. The Galactic center black hole and its mass may provide a lower limit for the mass of the sterile neutrino. The X-ray emission from neighboring galaxies, the Virgo cluster as well as the X-ray background give an upper limit at almost the same number; the Lyman α-forest gives also a lower limit. The smoothness of our halo, as well as the geometrical shape of large scale dark filaments, populated with huge galaxies with super-massive black holes give further clues.  Dwarf spheroidal galaxies may give the final clue, as they are dominated all the way by dark matter, and presumably are virgin galaxies from the early days of the cosmos. These dwarf galaxies suggest that the mass is less than 4 keV, while other arguments suggests a mass above 2 keV. The observation of the predicted X-ray emission line from dark matter decay may lead to a decisive step in determining the nature and mass of the dark matter particles, suggesting as one solution a Weakly Interacting Neutrino, or WIN, of 3±1 keV.

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