“Sterile” neutrinos are not sterile by virtueof their vacuum mixing with active neutrinos

Gives effective interaction strength of the sterile neutrino relative to thestandard Weak InteractionWeak Interaction

It is by virtue of these tiny interactions that sterile neutrinoscan be produced in the early universe or in supernovae

A heavy “sterile” neutrino can decay into a light“active” neutrino and a photon.

The final state light neutrino and the photon equally share the rest mass energy of the initial heavy neutrino.

Sterile Neutrino Dark Matter ???Sterile Neutrino Dark Matter ???

active-active neutrino scattering-induced decoherence

S. Dodelson & L. M. Widrow, Phys. Rev. Lett. 72, 17 (1994)

A. D. Dolgov & S. H. Hansen, Astropart. Phys. 16, 339 (2002)

Largely eliminated by the X-ray observations

But Some Models Are Still Viable . . .

lepton number-enhanced decoherence

low temperature inflaton

Higgs decay

M. Shaposhnikov & I. Tkachev, Phys. Lett. B 639, 414 (2006)

A. Kusenko, Phys. Rev. Lett. 97, 241301 (2006)K. Petraki & A. Kusenko (2007), arXiv:0711.4646

X. Shi & G. M. Fuller, Phys. Rev. Lett. 83, 3120 (1999)

K. Abazajian, G.M. Fuller, M. Patel, Phys. Rev. D 64, 023501 (2001)

C. Kishimoto & G.M. Fuller, Phys. Rev. D 78, 023524 (2008) arXiv:0802.3377

K. Petraki (20008), arXiv:0801.3470

J. Hidaka & G. M. Fuller, Phys. Rev. D 74, 125015 (2006) J. Hidaka & G. M. Fuller, Phys. Rev. D 76, 085013 (2007)

Ohio S

tate group

Fun with Compact Objects and ~ keV Rest Mass Sterile Neutrinos

Pulsar “Kicks” A. Kusenko & G. Segre, PRD 59, 061302 (1999); G. M. Fuller, A. Kusenko, I. Mocioiu, and S. Pascoli PRD 68, 103002 (2003).

Proto-neutron star “kick”-aided hydrodynamic supernovashock enhancement C. Fryer & A. Kusenko, Astrophys. J. (Suppl) 163, 335 (2006).

Active-sterile-active neutrino matter-enhanced alteration of collapsephysics and enhanced shock re-heatingJ. Hidaka & G. M. Fuller, Phys. Rev. D 74, 125015 (2006)

DAMA/LIBRA Low Energy Spectrum

CDMS Low Energy Spectrum

CDMS, DAMA/LIBRA Comparison