Constraints on Massive Axion-Like Particles from X-ray Observations of NGC1275

摘要

If axion-like particles (ALPs) exist, photons can convert to ALPs on passagethrough regions containing magnetic fields. The magnetised intracluster mediumof large galaxy clusters provides a region that is highly efficient atALP-photon conversion. X-ray observations of Active Galactic Nuclei (AGNs)located within galaxy clusters can be used to search for and constrain ALPs, asphoton-ALP conversion would lead to energy-dependent quasi-sinusoidalmodulations in the X-ray spectrum of an AGN. We use Chandra observations of thecentral AGN of the Perseus Cluster, NGC1275, to place bounds on massive ALPs upto m_a ~ 10^-11 eV, extending previous work that used this dataset to constrainmassless ALPs.