X-RAY AND ROTATIONAL LUMINOSITY CORRELATION AND MAGNETIC HEATING OF RADIO PULSARS

Abstract

Previous works have suggested a correlation between the X-ray luminosity and the rotational luminosity of radio pulsars. However, none of the obtained regression lines is statistically acceptable due to large scatter. We construct a statistical model that has an intrinsic – relation and reproduces the observed distribution about it by using a Monte Carlo simulator, which takes into account the effects obscuring the intrinsic relation, i.e., the anisotropy of radiation, additional heating, uncertainty in distance, and the detection limit of the instruments. From the ATNF pulsar catalog we collect 57 “ordinary radio pulsars” with significant detection and 42 with upper limits. The sample does not include high-magnetic-field pulsars (>10 13 G), which are analyzed separately. We obtain a statistically acceptable relation with c 1  = 1.03 ± 0.27 and L 0  = 10 35.38 . The distribution about the obtained – relation is reproduced well by the simulator. Pulsars with abnormally high fall into two types: one is the soft gamma-ray pulsars, and the other is pulsars that are thermally bright in comparison with the standard cooling curve. On the other hand, pulsars showing low are found to have dim pulsar wind nebulae (PWNs). We argue that there is an unknown mechanism that governs both the magnetospheric emission and the PWNs, and it might involve the production rate of electron–positron pairs. High-field pulsars form a population that is distinct from ordinary pulsars due to their excess luminosities.