Search for Axionic Dark Matter Using the Magnetar PSR J1745-2900
Jeremy Darling
Abstract
We report on a search for dark matter axion conversion photons from the magnetosphere of the Galactic Center magnetar PSR J1745-2900 using spectra obtained from the Karl G. Jansky Very Large Array (the National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.). No significant spectral features are detected. Using a hybrid model for PSR J1745-2900 and canonical assumptions about the dark matter density profile, we exclude axion models with axion-photon coupling ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}>6--34\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$ with 95% confidence over the mass ranges 4.2--8.4, 18.6--26.9, 33.0--41.4, 53.7--62.1, and $126.0--159.3\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$. If there is a dark matter cusp, the limits reduce to ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}>6--34\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$, which overlap some axion models for the observed mass ranges $>33\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$. These limits may be improved by modeling the stimulated emission that can boost the axion-photon conversion process.