Soft X-ray properties of the Geminga pulsar

Abstract

A soft-X-ray spectrum and pulse profile of the gamma-raypulsar Geminga, obtained with the ROSAT instrument, was analyzed andinterpreted in terms of thermal emission from the surface of theneutron star. It was found that the X-ray spectrum of Geminga consistsof two blackbody components, one with T1 = (5.2 +/- 1.0) x 10 exp5 K (which is in the range of model cooling curves for a neutronstar of age 3 x 10 exp 5 yr) and the other with T2 = about 3 x 10exp 6 K. The soft X-ray component is interpreted as photosphericcooling of much of the neutron star's surface area, while the small,hot region could be part of the much smaller polar cap heated byenergetic particles flowing inward from the magnetospheric acceleratorwhich is responsible for the production of Geminga gamma-rays.