arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2009.09744astro-ph.HE
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根据模拟的IXPE数据对吸积动力毫秒双星的中子星参数约束

Neutron star parameter constraints for accretion-powered millisecond pulsars from the simulated IXPE data

Tuomo Salmi, Vladislav Loktev, Karri Korsman, Luca Baldini, Sergey S. Tsygankov, Juri Poutanen

摘要:

我们已经模拟了X射线偏振数据,可以获得与成像X射线偏振探测器,当观察吸积动力毫秒双星。我们估计了SAX J1808.4 $-$ 3658所需的曝光时间,以便在所有能量通道上积分的测得的时间相关斯托克斯轮廓中获得不同的精度。我们发现,测量的相对误差强烈地依赖于观测者和发射热点的相对配置。斯托克斯$Q$和$U$参数中的最小相对误差作为观测时间$t$的函数的改进按$1/\sqrt{t}$缩放,并且跨越从200 ks曝光时间的30-90%到500 ks曝光时间的20-60%的范围(在19个相位箱中的数据箱的情况下)。模拟的数据也被用来预测如何准确测量的中子星的几何参数时,可以只建模$Q$和$U$参数,但不是通量。我们发现,观测者的倾角和热点同纬度可以确定优于10度的精度为我们考虑的大多数情况下。这些测量结果可以用来进一步约束中子星的质量和半径时,结合模型的X射线脉冲轮廓。

英文摘要:

We have simulated the X-ray polarization data that can be obtained with the Imaging X-ray Polarimetry Explorer, when observing accretion-powered millisecond pulsars. We estimated the necessary exposure times for SAX J1808.4$-$3658 in order to obtain different accuracies in the measured time-dependent Stokes profiles integrated over all energy channels. We found that the measured relative errors depend strongly on the relative configuration of the observer and the emitting hotspot. The improvement in the minimum relative error in Stokes $Q$ and $U$ parameters as a function of observing time $t$ scales as $1/\sqrt{t}$, and spans the range from 30-90% with 200 ks exposure time to 20-60% with 500 ks exposure time (in case of data binned in 19 phase bins). The simulated data were also used to predict how accurate measurements of the geometrical parameters of the neutron star can be made when modelling only $Q$ and $U$ parameters, but not the flux. We found that the observer inclination and the hotspot co-latitude could be determined with better than 10 deg accuracy for most of the cases we considered. These measurements can be used to further constrain neutron star mass and radius when combined with modelling of the X-ray pulse profile.

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