2025/11/25 by Kohri, Kazunori, Takahashi, Haruki
Physics and Astronomy · #Dark Matter and Cosmic Phenomena #Astrophysics and Cosmic Phenomena #Particle physics theoretical and experimental studies
paper · doi:10.48550/arxiv.2511.19848
In this paper, we derive the upper bounds on the coupling of axion-like particles (ALPs) with photon as a function of the mass by considering axion-photon conversion in the Crab Nebula. Previous studies have not considered the influence of the magnetic field within the Crab Nebula. The magnetic field plays a crucial role through the Synchrotron Self-Compton (SSC) process, in which high-energy electrons produce synchrotron radiation that is subsequently up-scattered by the same electrons via inverse Compton scattering to generate gamma rays. Therefore, neglecting the magnetic field in modeling leads to theoretical inconsistencies. In this work, we investigate the significance of the magnetic field effect and demonstrate that even differences in magnetic field modeling can substantially alter the conversion probability. We thus, for the first time, point out that proper consideration of the magnetic field is essential in ALP searches using gamma rays from the Crab Nebula. The resulting constraints reach up to a coupling of gaγγ \lesssim 1 × 10-11 \rm GeV-1 for ALP masses in the range 10-10 \rm eV \lesssim ma \lesssim 10-6 \rm eV.