Soft X-ray Spectrum Changes over the 35-Day Cycle in Hercules X-1 Observed with AstroSat SXT

IF 4.6 Q2 MATERIALS SCIENCE, BIOMATERIALS

ACS Applied Bio Materials Pub Date : 2024-07-15 DOI:10.3390/universe10070298

Denis Leahy , Riddhiman Sharma

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Abstract

Observations of the X-ray binary system Her X-1 by the AstroSat Soft X-ray Telescope (SXT) were carried out in 2020 through 2023 with the goals of measuring X-ray spectrum changes with the 35-day disk precession phase and measuring eclipses at different 35-day phases. Her X-1 exhibits a regular flux modulation with a period of ≃35 days with different intensity levels at various 35-day phases (called “states”). The four multi-day long observations were scheduled to cover most of these states. Each 35-day phase was determined using monitoring observations with the Swift Burst Alert Telescope (BAT). Nine eclipses were observed in the range of 35-day phases, with at least one eclipse during each observation. Data with dips were separated from data without dips. The variation in X-ray spectral parameters vs. 35-day phase shows the following: eclipse parameters are nearly constant, showing that the scattering corona does not change with 35-day phase; dips show an increase in covering fraction but not column density compared to non-dip data; the1 keV line normalization behaves similarly to the powerlaw normalization, consistent with an origin near the powerlaw emission region, likely the magnetospheric accretion flow from the inner disk onto the neutron star; and the blackbody normalization (area) is large (∼3×105 km2) during the Main High and Short High states, consistent with the inner edge of the accretion disk.

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用 AstroSat SXT 卫星观测到的海格力斯 X-1 在 35 天周期内的软 X 射线光谱变化

2020 年至 2023 年，AstroSat 软 X 射线望远镜（SXT）对 X 射线双星系统 Her X-1 进行了观测，目的是测量 X 射线频谱随 35 天磁盘前摄期的变化，并测量不同 35 天阶段的食相。Her X-1表现出周期为≃35天的有规律的通量调制，在不同的35天阶段（称为 "状态"）有不同的强度水平。四次长达数天的观测计划涵盖了这些状态中的大部分。每个 35 天阶段都是通过斯威夫特爆发预警望远镜（BAT）的监测观测确定的。在 35 天的阶段范围内共观测到九次日食，每次观测至少有一次日食。有日食的数据与无日食的数据被分开。X 射线光谱参数随 35 天相位的变化情况如下35 天相位的变化情况如下：日食参数几乎不变，表明散射日冕并不随 35 天相位的变化而变化；与无日食数据相比，日食数据显示覆盖率增加，但柱密度没有增加；1 keV线归一化的表现与幂律归一化相似，与幂律发射区附近的起源一致，可能是磁层吸积流从内盘流向中子星；在主高和短高态期间，黑体归一化（面积）很大（∼3×105 km2），与吸积盘的内缘一致。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

ACS Applied Bio Materials Chemistry-Chemistry (all)

CiteScore

9.40

自引率

2.10%

发文量

464

期刊介绍： ACS Applied Bio Materials is an interdisciplinary journal publishing original research covering all aspects of biomaterials and biointerfaces including and beyond the traditional biosensing, biomedical and therapeutic applications. The journal is devoted to reports of new and original experimental and theoretical research of an applied nature that integrates knowledge in the areas of materials, engineering, physics, bioscience, and chemistry into important bio applications. The journal is specifically interested in work that addresses the relationship between structure and function and assesses the stability and degradation of materials under relevant environmental and biological conditions.