Thursday, October 11, 2012

1210.2717 (James M. Cline et al.)

Cosmological origin of anomalous radio background    [PDF]

James M. Cline, Aaron C. Vincent
The ARCADE 2 collaboration and other experiments have reported a significant excess in the isotropic radio background, whose homogeneity cannot be reconciled with clustered sources. This suggests a cosmological origin prior to structure formation. We investigate several potential mechanisms and show that injection of relativistic electrons through late decays of a metastable particle can give rise to the observed excess radio spectrum either through Compton or synchrotron emission. However, these turn out to be in conflict with CMB bounds on the primordial magnetic field or on the injection of ionizing radiation. The simplest optimal scenario is with MeV-scale particles decaying into e+ e- at a redshift of z ~ 5, which is still in moderate conflict with the CMB constraints. Decays into exotic millicharged particles can alleviate the tension, if they emit synchroton radiation in conjunction with a sufficiently large background magnetic field of a dark U(1)' gauge field.
View original: http://arxiv.org/abs/1210.2717

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