Instability of dark energy with mass-varying neutrinos

Niayesh Afshordi, Matias Zaldarriaga, and Kazunori Kohri

Phys. Rev. D 72, 065024 – Published 30 September 2005

Abstract

An interesting dynamical model for dark energy which does not require extremely light scalar fields such as quintessence, and at the same time explains the (near) coincidence between the neutrino and dark energy densities is the model of dark energy coupled to mass-varying neutrinos (MaVaNs). Despite the attractions of this model, we show that, generically, this model contains a catastrophic instability which occurs when neutrinos become nonrelativistic. As a result of this instability, as neutrinos become nonrelativistic, they condense into neutrino nuggets which redshift away similar to cold dark matter, and thus cease to act as dark energy. Any stable MaVaNs dark energy model is extremely contrived and is virtually indistinguishable from a cosmological constant.

Received 27 June 2005

DOI:https://doi.org/10.1103/PhysRevD.72.065024

Authors & Affiliations

Niayesh Afshordi^1,*, Matias Zaldarriaga^1,2,†, and Kazunori Kohri^1,3,‡

¹Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, MS-51, 60 Garden Street, Cambridge, Massachusetts 02138, USA
²Jefferson Laboratory of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
³Department of Earth and Space Science, Graduate School of Science, Osaka University, Osaka 560-0043, Japan

^*Electronic address: nafshordi@cfa.harvard.edu
^†Electronic address: mzaldarriaga@cfa.harvard.edu
^‡Electronic address: kkohri@cfa.harvard.edu

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Vol. 72, Iss. 6 — 15 September 2005

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Physical Review D

covering particles, fields, gravitation, and cosmology