Constraints on axions and axionlike particles from Fermi Large Area Telescope observations of neutron stars
B. Berenji ; J. Gaskins ; M. Meyer ; - ASI Sponsor
Feb - 2016
DOI: 10.1103/PhysRevD.93.045019

journal : Physical Review D

Volume : 93 ; Issue : 4
type: Article Journal

We present constraints on the nature of axions and axionlike particles (ALPs) by analyzing gamma-ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong CP problem of particle physics, axions and ALPs are also possible dark matter candidates. We investigate axions and ALPs produced by nucleon-nucleon bremsstrahlung within neutron stars. We derive a phenomenological model for the gamma-ray spectrum arising from subsequent axion decays. By analyzing five years of gamma-ray data (between 60 and 200 MeV) for a sample of four nearby neutron stars, we do not find evidence for an axion or ALP signal; thus we obtain a combined 95% confidence level upper limit on the axion mass of 7.9×10−2  eV, which corresponds to a lower limit for the Peccei-Quinn scale fa of 7.6×107  GeV. Our constraints are more stringent than previous results probing the same physical process, and are competitive with results probing axions and ALPs by different mechanisms.

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Notes : VI. ACKNOWLEDGMENTSTheFermiLAT Collaboration acknowledges generous ongoing support from a number ofagencies and institutes that have supported both the development and the operation of theLAT as well as scientific data analysis. These include [...] theAgenzia Spaziale Italiana ...