Discovery of a keV-X-ray Excess in RX J1856.5--3754

Tomokage Yoneyama, Kiyoshi Hayashida, Hiroshi Nakajima +2

RX J1856.5$-$3754 is the brightest and nearest ($\sim 120$ pc) source among thermally emitting isolated neutron stars. Its spectra observed with {\sl XMM-Newton} and {\sl Chandra}…