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High-Energy Observations of the Binary Millisecond Pulsar PSR J0218+4232

L. Kuiper·W. Hermsen·F. Verbunt·T. Belloni·A. Lyne
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Abstract

We report the detection of pulsed X-ray emission ($4.9σ$) from the binary millisecond pulsar PSR J0218+4232 in a 100 ks ROSAT HRI observation. The pulse profile shows a sharp main pulse and an indication for a second weaker pulse at $\sim$ 0.47 phase separation. The pulsed fraction is 37 \pm 13%. PSR J0218+4232 was several times in the field of view of the high-energy $γ$-ray telescope EGRET and a source positionally consistent with the pulsar was detected above 100 MeV. Spatial and timing analyses of EGRET data indicate that the source is probably multiple: Between 0.1 GeV and 1 GeV PSR J0218+4232 is the most likely counterpart, while the BL Lac 3C66A is the best candidate above 1 GeV. If part of the EGRET signal truly belongs to the pulsar, then this would be the first millisecond $γ$-ray pulsar.

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L. Kuiper, W. Hermsen, F. Verbunt, T. Belloni, A. Lyne. 1998-12-22. High-Energy Observations of the Binary Millisecond Pulsar PSR J0218+4232. https://arxiv.org/abs/astro-ph/9812408

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