Title: Implementing and Verifying a Fourier Domain Approach to Fast Stochastic X-ray Polarimetry Timing Show Chinese title

Title: 实现和验证一种基于傅里叶域的快速随机X射线偏振测时方法

Abstract: The launch of the Imaging X-ray Polarimetry Explorer (IXPE), the first space-based polarimeter since 1978, offers a two order of magnitude improvement to the measurement of X-ray polarisation than its predecessor OSO-8, offering unprecedented precision for the measurement of polarisation degree and polarisation angle of X-ray sources. This advancement lends itself to the birth of a number of contemporary techniques to study Galactic compact objects, including X-ray polarimetry-timing, the study of how polarisation properties evolve over short timescales. However, the statistical nature of polarisation measurements poses a challenge for studies on arbitrarily short timescales, as a large number of photons are required to achieve statistically significant measurements of polarisation degree and angle for time-resolved analyses. Furthermore, if the polarisation variability is stochastic, then phase-folding techniques introduce systematic errors in the phase assignment of photons. Ingram and Maccarone presented a model independent Fourier-based technique that circumvents these issues. It can be used on arbitrarily short timescales for any kind of variability, whether aperiodic, quasi-periodic or purely periodic. Here we implement this method on real IXPE data. We address several instrumental effects and test the technique on X-ray pulsars, RX-J0440.9+4431 and Hercules X-1 . We verify that our technique recovers the polarisation variability signal that we already know to be there from typical phase-folding techniques. It will now be possible to study fast stochastic polarisation variability of X-ray sources, with applications including quasi-periodic oscillations, mass accretion rate fluctuations, and reverberation mapping. Show Chinese abstract

Abstract: 成像X射线偏振探测器（IXPE）的发射，自1978年以来的第一个空间偏振计，其X射线偏振测量精度比前身OSO-8提高了两个数量级，为X射线源的偏振度和偏振角测量提供了前所未有的精确度。 这一进展促成了许多当代技术的发展，用于研究银河系致密天体，包括X射线偏振测时技术，即研究偏振特性如何在短时间尺度上演化。 然而，偏振测量的统计性质对任意短时间尺度的研究构成了挑战，因为需要大量的光子才能实现偏振度和偏振角的统计显著测量，以进行时间分辨分析。 此外，如果偏振变化是随机的，那么相位折叠技术会在光子的相位分配中引入系统误差。 Ingram和Maccarone提出了一种模型无关的基于傅里叶的技术，可以规避这些问题。 该技术可以在任意短的时间尺度上使用，适用于任何类型的变异性，无论是非周期性的、准周期性的还是纯粹周期性的。 在这里，我们将这种方法应用于真实的IXPE数据。 我们处理了几种仪器效应，并在X射线脉冲星RX-J0440.9+4431和猎户座X-1上测试了该技术。 我们验证了我们的技术能够恢复我们已经知道存在的偏振变化信号，这是通过典型的相位折叠技术发现的。 现在可以研究X射线源的快速随机偏振变化，应用包括准周期振荡、质量吸积率波动和回波映射。