论文标题
脉冲星辐射和持续磁制动的黑寡妇形成
Black widow formation by pulsar irradiation and sustained magnetic braking
论文作者
论文摘要
黑寡妇是具有低质量同伴的毫秒脉冲星，在轨道上是几个小时的巨大群体，是太阳的质量。这些同伴大概是主要序列星的残余物，它们通过宿主Pulsar的高能辐射的Roche-Lobe Overflow和消融而失去了质量。虽然消融本身太弱，无法显着减少伴侣恒星的质量，但烧蚀的风伴对磁场，去除轨道角动量，从而保持稳定的Roche-Lobe溢出。我们使用台面恒星演化代码，并与分析估计相辅相成，以跟踪最初的主要序列伴侣，因为这种消融驱动的磁制动将它们减少到原始质量的一小部分。我们认为，即使对于低质量同伴，磁制动也仍然有效。我们模型的一个关键要素是，脉冲星的照射光度$ l _ {\ rm irr} $沉积在同伴大气中的能量，从而减慢了其开尔文 - 霍尔姆·霍尔特（Kelvin-Helmholtz）的冷却。我们发现，由费米$ l _ {\ rm irr} = 0.1-3 \，{\ rm l} _ \ odot $测量的高能发光性可以解释黑寡妇轨道时期的跨度。相同的$ l _ {\ rm irr} $范围重现了同伴的夜间温度，该温度凝聚在3000 K左右，从光光曲线中推断出来。
Black widows are millisecond pulsars with low-mass companions, a few per cent the mass of the sun, on orbits of several hours. These companions are presumably the remnants of main sequence stars that lost their mass through a combination of Roche-lobe overflow and ablation by the host pulsar's high-energy radiation. While ablation itself is too weak to significantly reduce the mass of the companion star, the ablated wind couples to its magnetic field, removes orbital angular momentum, and thus maintains stable Roche-lobe overflow. We use the MESA stellar evolution code, complemented by analytic estimates, to track initially main sequence companions as they are reduced to a fraction of their original mass by this ablation-driven magnetic braking. We argue that magnetic braking remains effective even for low-mass companions. A key ingredient of our model is that the irradiating luminosity of the pulsar $L_{\rm irr}$ deposits energy in the companion's atmosphere and thereby slows down its Kelvin-Helmholtz cooling. We find that the high-energy luminosities measured by Fermi $L_{\rm irr}=0.1-3\,{\rm L}_\odot$ can explain the span of black widow orbital periods. The same $L_{\rm irr}$ range reproduces the companions' night-side temperatures, which cluster around 3000 K, as inferred from optical light curves.
