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arXiv 1812.09030astro-ph.HE
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无线电和X射线模式转换PSR B0943 +10中的热发射和磁聚束

Thermal emission and magnetic beaming in the radio and X-ray mode-switching PSR B0943+10

Michela Rigoselli, Sandro Mereghetti, Roberto Turolla, Roberto Taverna, Valery Suleimanov, Alexander Y. Potekhin

摘要:

PSR B 0943 +10是一颗模式转换射电脉冲星,具有两种不同的射电和X射线发射模式。以前的研究,基于简单的组合的黑体和幂律模型,表明其X射线通量可以分解为脉冲热加上非脉冲非热分量。然而,如果PSR B 0943 +10是一个几乎对齐的转子看到极上,由无线电数据建议,它是很难再现高观察到的脉冲部分,除非磁波束包括在内。在这项工作中,我们重新分析了所有可用的X射线观测PSR B 0943 +10的同时无线电覆盖,模拟其热辐射与磁极帽覆盖的磁化氢气氛或与凝聚铁表面。凝聚的表面模型提供了很好的拟合的光谱的两个脉冲星模式,但是,类似的黑体,它不能重现所观察到的脉冲轮廓,除非一个额外的功率定律与特设调制被添加。相反,脉冲轮廓和相位分辨光谱很好地描述了使用氢气氛模型来描述极冠发射,加上非脉冲功率定律。对于较亮的X射线态(Q模式),我们得到了最佳拟合,温度kT约为0.09 keV,发射半径R约为260 m,磁场与根据定时参数推断的偶极场值4 × 10^12 G一致,磁轴和自旋轴之间的夹角很小,$ξ$ =5。对应于X射线暗态(B模式)的参数为kT~0.08 keV和R~170 m。

英文摘要:

PSR B0943+10 is a mode-switching radio pulsar characterized by two emission modes with different radio and X-ray properties. Previous studies, based on simple combinations of blackbody and power law models, showed that its X-ray flux can be decomposed in a pulsed thermal plus an unpulsed non-thermal components. However, if PSR B0943+10 is a nearly aligned rotator seen pole-on, as suggested by the radio data, it is difficult to reproduce the high observed pulsed fraction unless magnetic beaming is included. In this work we reanalyze all the available X-ray observations of PSR B0943+10 with simultaneous radio coverage, modeling its thermal emission with polar caps covered by a magnetized hydrogen atmosphere or with a condensed iron surface. The condensed surface model provides good fits to the spectra of both pulsar modes, but, similarly to the blackbody, it can not reproduce the observed pulse profiles, unless an additional power law with an ad hoc modulation is added. Instead, the pulse profiles and phase-resolved spectra are well described using the hydrogen atmosphere model to describe the polar cap emission, plus an unpulsed power law. For the X-ray brighter state (Q-mode) we obtain a best fit with a temperature kT~0.09 keV, an emitting radius R~260 m, a magnetic field consistent with the value of the dipole field of 4x10^12 G inferred from the timing parameters, and a small angle between the magnetic and spin axis, $ξ$=5. The corresponding parameters for the X-ray fainter state (B-mode) are kT~0.08 keV and R~170 m.

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