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arXiv 1503.05247astro-ph.HEastro-ph.SR
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极端黑寡妇PSR J1311-3430的光谱研究

A Spectroscopic Study of the Extreme Black Widow PSR J1311-3430

Roger W. Romani, Alexei V. Filippenko, S. Bradley Cenko

摘要:

我们报告了PSR J1311-3430的一系列光谱观测,PSR J1311-3430是一颗有氦星伴星的极端黑寡妇伽马射线脉冲星。在先前的研究中,我们估计中子星的质量为M_NS= 2.68+/-0.14 M_Sun(统计误差),基于有限的光谱学和基本(直接加热)光变曲线模型;然而,更大的模型依赖的系统学支配质量的不确定性。我们的新光谱学揭示了一系列复杂的源行为。He I伴星风辐射谱线的变化在宽波段测光中占主导地位,特别是在红滤光片或最小亮度附近,风通量应在自旋下降时间内完成伴星蒸发。伴星的受热面也经历了剧烈的耀斑,在恒星的20%以上达到40,000 K;这可能是由伴星产生的磁场驱动的。目前已较好地测量到伴星的光心径向速度,K_CoL = 615.4 ± 5.5km/s。我们检测到非正弦速度分量,由于加热面通量分布。使用我们的光谱切除耀斑和风线,我们产生大幅改善的光变曲线的同伴连续拟合。我们发现,推断的倾角和中子星质量,但是,仍然很敏感的约束加热模式。中子星的质量M_NS可能小于直接加热值,在赤道极端加热集中的情况下可能低至1.8 M_Sun。虽然我们还不能确定M_NS,但我们的数据表明,双星内部的激波重新处理了脉冲星的辐射,并加热了伴星。改进的光谱,特别是,模型,包括这样的冲击加热需要精确的参数测量。

英文摘要:

We report on a series of spectroscopic observations of PSR J1311-3430, an extreme black-widow gamma-ray pulsar with a helium-star companion. In a previous study we estimated the neutron star mass as M_NS= 2.68+/-0.14M_Sun (statistical error), based on limited spectroscopy and a basic (direct heating) light curve model; however, much larger model-dependent systematics dominate the mass uncertainty. Our new spectroscopy reveals a range of complex source behavior. The variable He I companion wind emission lines can dominate broad-band photometry, especially in red filters or near minimum brightness, and the wind flux should complete companion evaporation in a spin-down time. The heated companion face also undergoes dramatic flares, reaching 40,000K over 20% of the star; this is likely powered by a magnetic field generated in the companion. The companion center-of-light radial velocity is now well measured with K_CoL = 615.4+/-5.km/s. We detect non-sinusoidal velocity components due to the heated face flux distribution. Using our spectra to excise flares and wind lines, we generate substantially improved light curves for companion continuum fitting. We show that the inferred inclination and neutron star mass, however, remain sensitive to the poorly constrained heating pattern. The neutron star's mass, M_NS, is likely less than the direct heating value and could range as low as 1.8M_Sun for extreme equatorial heating concentration. While we cannot yet pin down M_NS, our data imply that an intrabinary shock reprocesses the pulsar emission and heats the companion. Improved spectra and, especially, models that include such shock heating are needed for precise parameter measurement.

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