Decaying Neutrinos and Large Scale Structure Formation

Abstract

We study the growth of density perturbations in a universe with unstable dark matter particles. The mass (m_ν) range 30 eV < m_ν< 10 keV with lifetimes ($t_d$) in the range 10^7 sec < t_d < 10^16 sec are considered. We calculate the COBE normalized matter power spectrum for these models. We find that it is possible to construct models consistent with observations for masses $m_ν> 50 eV by adjusting t_d so as to keep the quantity (m_ν(keV))^2 t_d(yr) constant at a value around 100. For m_ν< 1 keV the power spectrum has extra power at small scales which could result in an early epoch of galaxy formation. We do not find any value of t_d which gives a viable model in the mass range m_ν< 50 eV. We also consider the implications of radiatively decaying neutrinos---models in which a small fraction B << 1 of neutrinos decay into photons-which could possibly ionize the intergalactic medium (IGM) at high redshift. We show that the parameter space of decaying particles which satisfies the IGM observations does not give viable models of structure formation.

42 pages, 9 Postscript figures, Accepted in ApJ Supplement

References in corpus (4)

• Testing Cosmological Models Against the Abundance of Damped Lyman-Alpha Absorbers
• Cosmological Constraints from High-Redshift Damped Lyman-Alpha Systems
• Cosmology Using Cluster Internal Velocity Dispersions
• On The Source of Ionization of The Intergalactic Medium at $z\sim 2.4$

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• Particle decay in the early universe: predictions for 21 cm
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• An Isocurvature Mechanism for Structure Formation
• The effects of the small-scale behaviour of dark matter power spectrum on CMB spectral distortion
• Constraining neutrino decays with CMBR data
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• CMB and Large Scale Structure as a test of Mixed Models with n>1
• Cluster mass function in mixed models
• Metal Enrichment and Reionization Constraints on Early Star Formation
• Signatures of particle decay in 21 cm absorptions from first minihalos