Reionization: A probe for the stellar population and the physics of the early universe
- Zentrum fuer Astronomie der Universitaet Heidelberg, Institut fuer Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany)
We calculate the reionization history for different models of the stellar population and explore the effects of primordial magnetic fields, dark matter decay and dark matter annihilation on reionization. We find that stellar populations based on a Scalo-type initial mass function for Population II stars can be ruled out as sole sources for reionization, unless star formation efficiencies of more than 10% or very high photon escape fractions from the parental halo are adopted. When considering primordial magnetic fields, we find that the additional heat injection from ambipolar diffusion and decaying MHD turbulence has a significant impact on the thermal evolution and the ionization history of the post-recombination universe and on structure formation. The magnetic Jeans mass changes the typical mass scale of the star-forming halos, and depending on the adopted stellar model we derive upper limits to the magnetic field strength between 0.7 and 5 nG (comoving). For dark matter annihilation, we find an upper limit to the thermally averaged mass-weighted cross section of <{sigma}v>/m{sub DM}{<=}10{sup -33} cm{sup 3}/s/eV. For dark matter decay, our calculations yield a lower limit to the lifetime of dark matter particles of {tau}{>=}3x10{sup 23} s. These limits are in agreement with constraints from recombination and provide an independent confirmation at a much later epoch.
- OSTI ID:
- 21254375
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 78, Issue 8; Other Information: DOI: 10.1103/PhysRevD.78.083005; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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