Constraints on non-resonant photon-axion conversion from the Planck satellite data
The non-resonant conversion of Cosmic Microwave Background (CMB) photons into scalar as well as light pseudoscalar particles such as axion-like particles (ALPs) in the presence of turbulent magnetic fields can cause a unique, spatially fluctuating spectral distortion in the CMB. We use the publicly available Planck temperature maps for the frequency channels (70–545 GHz) to obtain the first ALP distortion map using 45% clean part of the sky. The 95th percentile upper limit on the RMS fluctuation of ALP distortions from the cleanest part of the CMB sky at 15 arcmin angular resolution is 18.5 × 10−6. The RMS fluctuation in the distortion map is also consistent with different combinations of frequency channels and sky-fractions.