TY - EJOUR AU - Jeong, Kwangsik AU - Kawasaki, Masahiro AU - Takahashi, Fuminobu TI - Axions as Hot and Cold Dark Matter IS - DESY-13-181 M1 - DESY-2013-01123 M1 - DESY-13-181 M1 - arXiv:1310.1774 M1 - TU-948 M1 - ICRR-661-2013-10 M1 - IPMU13-0197 PY - 2013 AB - The presence of a hot dark matter component has been hinted at 3 sigma by a combination of the results from different cosmological observations. We examine a possibility that pseudo Nambu-Goldstone bosons account for both hot and cold dark matter components. We show that the QCD axions can do the job for the axion decay constant f_a < O(10^10) GeV, if they are produced by the saxion decay and the domain wall annihilation. We also investigate the cases of thermal QCD axions, pseudo Nambu-Goldstone bosons coupled to the standard model sector through the Higgs portal, and axions produced by modulus decay. LB - PUB:(DE-HGF)25 ; PUB:(DE-HGF)15 UR - https://bib-pubdb1.desy.de/record/154830 ER -