Radiatively decaying neutrinos and photoionization of the universe at high redshifts

Sethi, S.K.

Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/4901

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DC Field	Value	Language
dc.contributor.author	Sethi, S.K.	-
dc.date.accessioned	2012-07-14T09:45:50Z	-
dc.date.available	2012-07-14T09:45:50Z	-
dc.date.issued	1997	-
dc.identifier.citation	Astrophysical Journal, 1997 , Vol.474, p13	en
dc.identifier.issn	0004-637X	-
dc.identifier.issn	1538-4357 (Online)	-
dc.identifier.uri	http://hdl.handle.net/2289/4901	-
dc.description	Restricted Access	en
dc.description.abstract	The ionization history of the universe in the presence of radiatively decaying neutrinos with masses between 30 eV and a few keV is studied. We consider a model in which most of the neutrinos decay into invisible particles at a rate t^{-1}_ν > t^{-1}0, with t0 being the present age of the universe, while a small fraction of neutrinos, B, decay radiatively. We follow the evolution of the fraction of neutral hydrogen (H I), neutral helium (He I), and singly ionized helium (He II) in the diffuse intergalactic medium (IGM), taking into account the absorption of decay photons by hydrogen and helium in the diffuse IGM and the Ly alpha systems. The constraints on radiatively decaying neutrinos from the spectrum of cosmic background radiation, SN 1987A, the cooling of red giants, and the diffuse extragalactic background of photons are also considered. We derive the parameter space---spanned by the mass of the unstable neutrino m nu , t nu , and B---allowed by the Gunn-Peterson (GP) tests for H I, He I, and He II, the proximity effect, and Ly alpha emission at high redshifts. It is shown that the ionization state of the diffuse IGM, as required by the GP tests, can be explained without violating any other astrophysical or cosmological constraint on the model. We also investigate the implications of recently observed resonant neutral helium lines at z ~= 2 on the radiatively decaying neutrino scenario; this observation rules out almost all of the parameter space for neutrino masses >~ 50 eV.	en
dc.language.iso	en	en
dc.publisher	Institute of Physics	en
dc.relation.uri	http://adsabs.harvard.edu/abs/1997ApJ...474...13S	en
dc.relation.uri	http://dx.doi.org/10.1086/303427	en
dc.rights	1997 The American Astronomical Society	en
dc.subject	cosmology: theory	en
dc.subject	cosmology: early universe	en
dc.subject	elementary particles	en
dc.subject	galaxies: intergalactic medium	en
dc.title	Radiatively decaying neutrinos and photoionization of the universe at high redshifts	en
dc.type	Article	en
Appears in Collections:	Research Papers (A&A)

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