2010/11/30 by Davide Cadamuro, Steen Hannestad, Georg Raffelt +1 · 1 citation
Physics and Astronomy · #hep-ph #astro-ph.CO
paper · pdf · doi:10.1088/1475-7516/2011/02/003
published as JCAP 1102:003,2011 · 19 pages, 10 figures
arxiv created 2011/01/21 · arxiv updated 2015/03/17
Axions with mass greater than 0.7 eV are excluded by cosmological precision data because they provide too much hot dark matter. While for masses above 20 eV the axion lifetime drops below the age of the universe, we show that the cosmological exclusion range can be extended from 0.7 eV till 300 keV, primarily by the cosmic deuterium abundance: axion decays would strongly modify the baryon-to-photon ratio at BBN relative to the one at CMB decoupling. Additional arguments include neutrino dilution relative to photons by axion decays and spectral CMB distortions. Our new cosmological constraints complement stellar-evolution limits and laboratory bounds.