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A New Upper Limit on the Total Neutrino Mass from the 2dF Galaxy Redshift Survey. [astro-ph/0204152 v3 (14 June 2002)] [ Phys. Rev. Lett. 89, 061301 (5 August 2002)]. M.P. Journal Club 21 st November 2002. Neutrino Mass?. In Standard Model, assumed that neutrinos have no mass
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A New Upper Limit on the Total Neutrino Mass from the 2dF Galaxy Redshift Survey [astro-ph/0204152 v3 (14 June 2002)] [Phys. Rev. Lett. 89, 061301 (5 August 2002)] M.P. Journal Club 21st November 2002 Mark Pearce [pearce@particle.kth.se]
Neutrino Mass? • In Standard Model, assumed that neutrinos have no mass • This is by choice and is not required a priori • ’Recent’ data from atmospheric and solar neutrino experiments indicate that neutrinos can oscillate between flavour eigenstates • If this is so, at least one of the neutrinos MUST have mass • NB: oscillation probability Dm2 • Neutrino mass scale could be determined from endpoint of 3H b-decay spectrum Mark Pearce [pearce@particle.kth.se]
Neutrinos as Dark Matter ? From CMB anisotropy Dark Matter Exotic Normal [astro-ph/0210306] Neutrinos Baryons Mark Pearce [pearce@particle.kth.se] • Massive neutrinos are an excellent candidate for Dark Matter ! • But massive neutrinos have consequences for galactic structure...
Structure Formation Massive neutrinos dominate Mark Pearce [pearce@particle.kth.se] DEFW / CFA survey Cold Dark Matter dominates
Results ! • 2dFGRS power spectrum has been analysed • Allows upper bound on fn = Wn / Wm to be determined... • fn < 0.13 @ 95% C.L. • Taking Wmh2 = 0.15 (from CMB) mn,tot < 1.8 eV (since Wnh2 = mn,tot / 94 eV) • This is tighter than the best limits from particle physics experiments! [h = H0 / 100 km s-1 Mpc-1] PDG 2002 Mark Pearce [pearce@particle.kth.se]