ar X iv : a st ro - p h / 01 04 14 9 v 1 9 A pr 2 00 1 ASCA Detection of Pulsed X - ray Emission from PSR J 0631 + 1036

ASCA’s long look at the 288 millisecond radio pulsar, PSR J0631+1036, reveals coherent X-ray pulsation from this source for the first time. The source was first detected in the serendipitous Einstein observation and later identified as a radio pulsar. Possible pulsation in the gamma-ray band has been detected from the CGRO EGRET data (Zepka, et al. 1996). The X-ray spectrum in the ASCA band is characterized by a hard power-law type emission with a photon index ≃ 2.3, when fitted with a single power-law function modified with absorption. An additional blackbody component of kT ≃ 0.14 keV increases the quality of the spectral fit. The observed X-ray flux is 2.1× 10 ergs s cm in the 1-10 keV band. We find that many characteristics of PSR J0631+1036 are similar to those of middle-aged gamma-ray pulsars such as PSR B1055-52, PSR B0633+17 (Geminga), and PSR B0656+14. Subject headings: pulsars: general — pulsars: individual (PSR J0631+1036) — X-rays: stars: neutron