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摘要
We investigate the formation and evolutionary sequences of Galactic intermediate-and low-mass X-ray binaries (I/LMXBs) by combining binary population synthesis (BPS) and detailed stellar evolutionary calculations. Using an updated BPS code we compute the evolution of massive binaries that leads to the formation of incipient I/LMXBs and present their distribution in the initial donor mass versus initial orbital period diagram. We then follow the evolution of the I/LMXBs until the formation of binary millisecond pulsars (BMSPs). We find that the birthrate of the I/LMXB population is in the range of 9 x 10(-6) -3.4 x 10(-5) yr(-1), compatible with that of BMSPs that are thought to descend from I/LMXBs. We show that during the evolution of I/LMXBs they are likely to be observed as relatively compact binaries with orbital periods less than or similar to 1 day and donor masses less than or similar to 0.3M(circle dot). The resultant BMSPs have orbital periods ranging from less than 1 day to a few hundred days. These features are consistent with observations of LMXBs and BMSPs. We also confirm the discrepancies between theoretical predictions and observations mentioned in the literature, that is, the theoretical average mass transfer rates (similar to 10(-10) M-circle dot yr(-1)) of LMXBs are considerably lower than observed, and the number of BMSPs with orbital periods similar to 0.1-10 days is severely underestimated. These discrepancies imply that something is missing in the modeling of LMXBs, which is likely to be related to the mechanisms of the orbital angular momentum loss.
- 出版日期2015-8-10
- 单位南京大学
