Growing neutrinos as a solution of the "why now" problem for dark energy

by Prof. Christof Wetterich (U. of Heidelberg)

Wednesday 23 Jul 2008, 11:00 → 12:00 Europe/Zurich

1/1-025 (CERN)

The time evolution of a cosmological scalar field can be stopped by an increasing mass of the neutrinos. This leads to a transition from a cosmological scaling solution with dynamical dark energy at early time to a cosmological constant dominated universe at late time. The trigger for the transition is set at the time when the neutrinos become non-relativistic , corresponding to a redshift z ~ 5.

This is a possible solution of the "why now " problem. The present dark energy density is related to the present neutrino mass.We discuss a particle physics realization of this ``growing matter'' scenario , which explains why the neutrino coupling to the cosmological scalar field is somewhat larger than the gravitational coupling. A simple and realistic dark energy cosmology can be obtained in this way.

References:

• "Growing Matter", by Luca Amendola , Marco Baldi, Christof Wetterich, arXiv:0706.3064 [astro-ph]
• "Growing neutrinos and cosmological selection", by C. Wetterich, PLB655:201-208,2007, arXiv:0706.4427 [hep-ph]
• "Neutrino clustering in growing neutrino quintessence", by D.F. Mota, V. Pettorino, G. Robbers, C. Wetterich, PLB663:160-164,2008, arXiv:0802.1515 [astro-ph]
• "Dark energy from mass varying neutrinos", by Rob Fardon, Ann E. Nelson, Neal Weiner, JCAP 0410:005,2004, astro-ph/0309800
• "On the stability of dark energy with mass-varying neutrinos", by Niayesh Afshordi, Matias Zaldarriaga, Kazunori Kohri, PRD72:065024,2005, astro-ph/0506663
• "Neutrino Dark Energy -- Revisiting the Stability Issue", by Ole Eggers Bjaelde, Anthony W. Brookfield, Carsten van de Bruck, Steen Hannestad, David F. Mota, Lily Schrempp, Domenico Tocchini-Valentini, JCAP 0801:026,2008. arXiv:0705.2018 [astro-ph]