论文标题
基于Chandra光谱的共生系统RT CRU的长期X射线变异性
Long-term X-ray Variability of the Symbiotic System RT Cru based on Chandra Spectroscopy
论文作者
论文摘要
RT CRU属于罕见的硬X射线发射共生学，其起源尚未完全理解。在这项工作中，我们基于Chandra天文台的观察结果对RT CRU的X射线发射进行了详细的光谱分析，并在2015年使用低分辨率摄像机光谱仪（HRC-S）对高分辨率的摄像机光谱仪（HRC-S）进行了高分辨率摄像机光谱仪（HRC-S）的观察结果，并在高级能量传输光栅（HETG）上对高级CCD Imaging Speanl spras（HETG）进行了ccd Image s-s-army（ACMA）模型（ACS-SMMA模型）。按时间平均温度为$ kt \ sim 1.3 $ kev，而$ kt \ sim 9.6 $ kev根据时间平均的ACIS-S/HETG，hrc-s/letg频谱的平均温度为$ kt \ sim 1.3 $ kev。 HRC-S中发现的软热等离子体发射组件（$ \ sim1.3 $ keV）被密集的材料（$> 5 \ times 10^{23} $ cm $^{ - 2} $）大大遮盖。在光曲线中看到的多个可变性可能是由于吸收材料的变化覆盖了硬盘内部层中硬X射线源或固有发射机制。为了了解可变性，我们提取了“低/硬”和“高/软”光谱状态中的光谱，这表明在ACIS-S和HRC-S的低/硬态下的血浆温度较高。该源还具有6.4 keV的荧光铁发射线，这可能是由于吸收盘或致密吸收器的反射发出的，这在HRC-S时期与ACIS-S相比是两倍。在HRC-S中鉴定的软热组件可能表明，使用高分辨率成像观测值应进行进一步评估的射流。
RT Cru belongs to the rare class of hard X-ray emitting symbiotics, whose origin is not yet fully understood. In this work, we have conducted a detailed spectroscopic analysis of X-ray emission from RT Cru based on observations taken by the Chandra Observatory using the Low Energy Transmission Grating (LETG) on the High-Resolution Camera Spectrometer (HRC-S) in 2015 and the High Energy Transmission Grating (HETG) on the Advanced CCD Imaging Spectrometer S-array (ACIS-S) in 2005. Our thermal plasma modeling of the time-averaged HRC-S/LETG spectrum suggests a mean temperature of $kT \sim 1.3$ keV, whereas $kT \sim 9.6$ keV according to the time-averaged ACIS-S/HETG. The soft thermal plasma emission component ($\sim1.3$ keV) found in the HRC-S is heavily obscured by dense materials ($> 5 \times 10^{23}$ cm$^{-2}$). The aperiodic variability seen in its light curves could be due to changes in either absorbing material covering the hard X-ray source or intrinsic emission mechanism in the inner layers of the accretion disk. To understand the variability, we extracted the spectra in the "low/hard" and "high/soft" spectral states, which indicated higher plasma temperatures in the low/hard states of both the ACIS-S and HRC-S. The source also has a fluorescent iron emission line at 6.4 keV, likely emitted from reflection off an accretion disk or dense absorber, which was twice as bright in the HRC-S epoch compared to the ACIS-S. The soft thermal component identified in the HRC-S might be an indication of a jet that deserves further evaluations using high-resolution imaging observations.
