Gamma-ray spectral modulations of Galactic pulsars caused by photon-ALPs mixing

Understand

Well-motivated extensions of the standard model predict ultra-light and fundamental pseudo-scalar particles (e.g., axions or axion-like particles: ALPs).

• Similarly to the Primakoff-effect for axions, ALPs can mix with photons and consequently be searched for in laboratory experiments and with astrophysical observations.
• Here, we search for energy-dependent modulations of high-energy gamma-ray spectra that are tell-tale signatures of photon-ALPs mixing.
• To this end, we analyze the data recorded with the Fermi -LAT from Galactic pulsars selected to have a line of sight crossing spiral arms at a large pitch angle.