Abstract:
X-ray binaries, consisting of a compact object (either a black hole or a neutron star) accreting matter from a companion star, are among the most luminous sources of high-energy radiation in the universe. These systems serve as natural laboratories for studying fundamental physics under extreme conditions, including strong gravitational fields, rapid rotation, and intense magnetic fields. Despite decades of study, critical questions remain unanswered regarding the accretion processes, variability mechanisms, and the interplay between accretion and outflows in X-ray binaries. This thesis addresses these challenges by investigating the spectral and timing properties of X-ray binaries through multi-satellite observations and advanced data analysis techniques. The content includes several published articles (see the Appendix).
The first chapter introduces the motivation and significance of the study, highlighting key challenges in high-energy astrophysics. It begins with an overview of X-ray bina- ries, emphasizing their unique characteristics and astrophysical relevance. Historical developments in X-ray astronomy, from the discovery of Sco X-1 to the contributions of modern observatories such as eROSITA, NICER, NuSTAR, XMM-Newton, and Insight-HXMT, are discussed. Additionally, the study’s novel contributions are out- lined, particularly the application of advanced time-domain analysis methods and the integration of multi-mission data to achieve comprehensive insights.
The second chapter establishes the theoretical and observational foundations of X-ray binary research. This includes a detailed explanation of essential concepts such as accretion physics, quasi-periodic oscillations (QPOs), spectral state transitions, and spin dynamics, which are critical for understanding the physical mechanisms governing X-ray binaries. The chapter also summarizes unresolved scientific questions, such as the physical origins of QPOs, the role of magnetic fields in accretion processes, and the coupling between spectral state transitions and relativistic jets.
The methodological framework and data sources are presented in a dedicated chapter. This study employs multi-satellite observations to analyze the spectral and timing properties of X-ray binaries across a broad energy range. The contributions of each observatory are detailed: eROSITA’s wide-field surveys reveal variability patterns in transient X-ray sources, NICER’s high temporal resolution facilitates precise timing analysis, NuSTAR provides critical insights into high-energy spectral components, XMM-Newton delivers high-resolution spectroscopy of accretion disks, and Insight- HXMT contributes to the study of transient phenomena and hard X-ray emissions.
The results are divided into two main sections, focusing on black hole and neutron star X-ray binaries, respectively. For black hole systems, the findings highlight significant spectral and temporal variability, with key phenomena such as state transitions and disk wind launching explored in detail. Spectral analyses reveal correlations between changes in disk structure and relativistic outflows, while timing analyses of QPOs provide insights into accretion dynamics near the event horizon. These results contribute to a deeper understanding of accretion-ejection coupling and the feedback processes associated with black hole growth and galaxy evolution.
For neutron star systems, the study investigates spin evolution and variability pat- terns. High-resolution timing data uncover complex pulsation profiles and anti-glitch phenomena, offering new perspectives on magnetospheric accretion and dense matter physics.
This thesis also highlights the limitations of current observational and analytical methods, such as the challenges posed by faint signals and incomplete temporal coverage. It identifies opportunities for future research, including the integration of multi-wavelength and multi-messenger data to further explore compact object dynamics.
In conclusion, this thesis advances the understanding of X-ray binaries by providing a comprehensive analysis of their spectral and timing properties through multi-mission observations. The findings contribute to a deeper understanding of accretion processes, and variability mechanisms in X-ray binaries, addressing critical gaps in current knowledge. Furthermore, the study establishes a foundation for future research aimed at bridging observational and theoretical aspects of high-energy astrophysics, ultimately enhancing our understanding of the universe’s most extreme environments.
X-ray Binaries