THE NATURE OF LIGHT DARK MATTER Peter L. Biermann ...

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Our recent work • Pulsar kicks, velocities up to 1000 km/s – see the guitar nebula – (Kusenko 2004) range: 2 to 20 keV • ! Transition from active neutrino to weakly interacting neutrino to prevent scattering: right handed neutrino! • Early growth of black holes (Munyaneza & Biermann 2005) range: 12 - 450 keV: ! Fermion • Aspen September 2005: Overlap - Eureka! • From increased secondary ionization molecular Hydrogen formed more abundantly, and so star formation triggered early (Biermann & Kusenko 2007; Stasielak, Biermann & Kusenko 2006) – this removed major obstacle (Yoshida et al. 2003) for this known proposal 6
First star formation • Sterile neutrinos decay into an active neutrino and a photon (of half the mass in energy) • After redshift about 40 no absorption anymore, before fraction of ionized atoms (η fraction of photon energy into ionization) x (s) e ∼ 0.2 (1+z) 0.3 3/2 ( η • Formation of H2 via H − ) ( ms 7 keV )5 ( sin2 θ 0.8 10 −9) • Level of H2 above 5 10 −4 (Tegmark et al. 1997) strong cooling • Almost an order of magnitude enhancement, with maximum at redshift 80 • Corresponding heating cancels effect for redshifts < 20 (Mapelli, Ripamonti 2006) 7
Page 1 and 2: THE NATURE OF LIGHT DARK MATTER Pet
Page 3 and 4: Dark Matter: Some history Sterile n
Page 5: Background • They can be produced
Page 9 and 10: Primordial magnetic fields • Ioni
Page 11 and 12: X-ray background • 2005 - 2007: B
Page 13 and 14: Galaxies Work of group around G. Gi
Page 15 and 16: Acknowledgements Support for PLB is
Page 17 and 18: M., Patel, M., Phys. Rev. D 64, id.
Page 19 and 20: [16] “Ultra high energy cosmic ra
Page 21 and 22: [25] “Pulsar kicks from neutrino
Page 23 and 24: [35] “The νMSM, dark matter and
Page 25: [43] “Early Structure Formation a

THE NATURE OF LIGHT DARK MATTER Peter L. Biermann ...

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