High Energy Theory Seminar

Axions may be produced thermally inside the cores of neutron stars (NSs), escape the stars due to their weak interactions with matter, and subsequently convert into X-rays in the magnetic fields surrounding the NSs.  I will describe a hard X-ray search from 2 - 8 keV for X-rays arising from this emission mechanism from the nearby Magnificent Seven isolated NSs using archival XMM-Newton and Chandra data.  This search leads to the strongest limits to-date on the product of the axion-photon and axion-nucleon couplings for axion masses below ~1e−4 eV. Moreover, I will show that an observed excess of hard X-rays from the Magnificent Seven may arise from axions, and I will discuss near-term measurements to help rule out or confirm this possibility.