标题： 低质量X射线双星暂现源的爆发率与轨道周期之间的关系 显示英文标题

标题： The relation between outburst rate and orbital period in low-mass X-ray binary transients

摘要： 我们基于过去几十年观测到的爆发研究了低质量X射线双星暂现源（LMXBTS）的爆发特性。爆发率是根据Swift/BAT、RXTE/ASM和MAXI的X射线监测数据以及文献中的先前报告估算的。 我们发现几乎所有轨道周期低于$\sim$12小时的LMXBTS在这次观测中仅表现出一次爆发。长周期（$P_{\rm orb} \gtrsim$12小时）和短周期（$P_{\rm orb} \lesssim$12小时）系统之间的爆发率存在系统性差异。 我们推断，质量传递率是造成这种系统性差异的原因，因为盘不稳定性模型（DIM）表明，质量传递率是影响宁静时间的关键因素。长周期和短周期LMXBTS之间的爆发率差异可能是由于供体在不同演化阶段的不同质量传递机制造成的。 根据单星的演化轨迹，我们得出了宿主有亚巨星供体的X射线双星的临界轨道周期。临界轨道周期（$P_{\rm orb,crit}=$12.4小时）与从爆发率统计中获得的上述轨道周期边界一致。 此外，我们发现在供体恒星光谱型为III/IV的样本中，爆发率与轨道周期之间存在负相关。黑洞子样本的最佳拟合幂律指数大致与那些供体恒星已经离开主序的系统的理论预测一致。 显示英文摘要

摘要： We have investigated the outburst properties of low-mass X-ray binary transients (LMXBTs) based on a comprehensive study of the outbursts observed in the past few decades. The outburst rates were estimated based on the X-ray monitoring data from Swift/BAT, RXTE/ASM and MAXI, and previous reports in the literature. We found that almost all LMXBTs with the orbital period below $\sim$12 hr showed only one outburst in these observations. There are systematic difference in the outburst rate between long-period ($P_{\rm orb} \gtrsim$ 12 hr) and short-period ($P_{\rm orb} \lesssim$ 12 hr) systems. We infer that mass transfer rate is responsible for the systematic difference, since the disk instability model (DIM) suggested that the mass transfer rate is a key factor affecting the quiescence time. The difference in outburst rate between long-period and short-period LMXBTs is probably due to the different mass transfer mechanism at different evolutionary stages of the donors. Based on the evolutionary tracks of single stars, we derived the critical orbital period for X-ray binaries that harbor a subgiant donor in various metallicity. The critical orbital period ($P_{\rm orb,crit}=$12.4 hr) is consistent with the above orbital period boundary obtained from the statistics of outburst rates. Furthermore, we found a negative correlation between the outburst rate and the orbital period in the samples for which the luminosity class of the donor star is III/IV. The best-fitting power-law index for the black hole subsamples is roughly consistent with the theoretical prediction for those systems with a donor star evolved off the main sequence.