Optical Spectroscopy and Demographics of Redback Millisecond Pulsar Binaries
Optical Spectroscopy and Demographics of Redback Millisecond Pulsar Binaries
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DOI：
10.3847/1538-4357/aafbaa
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发表时间：
2018-12
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通讯作者：
J. Strader;S. Swihart;L. Chomiuk;A. Bahramian;Christopher T. Britt;C. C. Cheung-C.;K. Dage;J. Halpern-J.-H
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作者：
J. Strader;S. Swihart;L. Chomiuk;A. Bahramian;Christopher T. Britt;C. C. Cheung-C.;K. Dage;J. Halpern-J.-H
我们首次给出了五颗已确认的(或强烈候选的)红背毫秒脉冲星双星的光学光谱，获得了每一颗伴星的完整的径向速度曲线。在14个已确认的和10个候选场红背的背景下，讨论了这些具有低质量、富氢伴星的毫秒脉冲星双星的性质。我们发现红背星系的中子星质量中值为1.78±0.09M⊙，色散为σ=0.21±0.09。质量超过2M⊙的中子星与目前的观测结果是一致的，但并不是严格要求。红背同伴的平均质量为0.36±0.04M⊙，散布σ=0.15±0.04M⊙，尾巴可能延伸到0.7M-0.9M⊙。候选红背往往比确认的红背有更高的伴生质量，这表明在这些更大的候选系统中，可能存在着对无线电脉动探测的选择偏见。红背和质量较小的黑寡妇之间的伴生质量分布仍然是强烈的双峰分布，这是这些系统进化模型的一个重要制约因素。在红背中，将脉冲星自旋向下能量转换为γ-射线光度的中位数效率为∼10%。
We present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. The properties of these millisecond pulsar binaries with low-mass, hydrogen-rich companions are discussed in the context of the 14 confirmed and 10 candidate field redbacks. We find that the neutron stars in redbacks have a median mass of 1.78 ± 0.09 M⊙ with a dispersion of σ = 0.21 ± 0.09. Neutron stars with masses in excess of 2 M⊙ are consistent with, but not firmly demanded by, current observations. Redback companions have median masses of 0.36 ± 0.04 M⊙ with a scatter of σ = 0.15 ± 0.04 M⊙, and a tail possibly extending up to 0.7–0.9 M⊙. Candidate redbacks tend to have higher companion masses than confirmed redbacks, suggesting a possible selection bias against the detection of radio pulsations in these more massive candidate systems. The distribution of companion masses between redbacks and the less massive black widows continues to be strongly bimodal, which is an important constraint on evolutionary models for these systems. Among redbacks, the median efficiency of converting the pulsar spin-down energy to γ-ray luminosity is ∼10%.