Measurements of the angular momentum (spin) of astrophysical black holes are extremely important, as they provide information on the black hole formation and evolution. We present simulated observations of a X-ray binary system with the Imaging X-ray Polarimetry Explorer (IXPE), with the aim to study the robustness of black hole spin and geometry measurements using X-ray polarimetry. As a representative example, we used the parameters of GRS 1915+105 in its former unobscured, soft state. In order to simulate the polarization properties, we modeled the source emission with a multicolor blackbody accounting for thermal radiation from the accretion disk, including returning radiation. Our analysis shows that the polarimetric observations in the X-ray waveband will be able to estimate both spin and inclination of the system with a good precision (without returning radiation we obtained for the lowest spin $Δa \leq 0.4$ (0.4/0.998 $\sim$ 40%) for spin and $Δi \leq 30^\circ$ (30$^\circ$/70$^\circ$ $\sim$ 43%) for inclination, while for the higher spin values we obtained $Δa \leq 0.12$ ($\sim$ 12%) for spin and $Δi \leq 20^\circ$ ($ \sim $ 29%) for inclination, within 1$ σ$ errors). When focusing on the case of returning radiation and treating inclination as a known parameter, we were able to successfully reconstruct spin and disk albedo in $Δa \leq 0.15$ ($\sim$ 15%) interval and $Δ$ albedo $\leq 0.45$ (45%) intervals within 1$ σ$ errors. We conclude that X-ray polarimetry will be a useful tool to constrain black hole spins, in addition to timing and spectral-fitting methods.
Astronomical X-ray Polarimetry as a diagnostic for questions of fundamental Physics. What we learned from the Imaging X-Ray Polarimetry Explorer (IXPE)
The First X-Ray Polarimetry of an Eclipsing Low-Mass X-Ray Binary: Serendipitous IXPE Observation of AX J1745.6-2901
Universities Space and Research Association（美国大学太空研究协会）；Clemson University（克莱姆森大学）；Newcastle University（纽卡斯尔大学）；Columbia University（哥伦比亚大学）；Tor Vergata University of Rome（罗马第二大学）；Ehime University（爱媛大学）；Astronomical Institute of the Czech Academy of Sciences（捷克科学院天文研究所）；University of Turku（图尔库大学）；Massachusetts Institute of Technology（麻省理工学院）；KTH Royal Institute of Technology（瑞典皇家理工学院）；Stockholm University（斯德哥尔摩大学）；University of Southampton（南安普顿大学）；Michigan State University（密歇根州立大学）
The First X-ray Polarimetry of GRS 1739--278 Reveals Its Rapidly Spinning Black Hole
State Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理国家重点实验室）；University of Chinese Academy of Sciences（中国科学院大学）；Astronomical Institute of the Czech Academy of Sciences（捷克科学院天文研究所）；Department of Astronomy, University of Geneva（日内瓦大学天文系）；Fluid and Complex Systems Centre, Coventry University（考文垂大学流体与复杂系统中心）；INAF—Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所空间天体物理学和行星科学研究所）；Department of Physics and Astronomy, University of Southampton（南安普顿大学物理与天文系）；Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre（罗马第三大学数学与物理系）；NASA Marshall Space Flight Center（美国国家航空航天局马歇尔太空飞行中心）
Stanford University（斯坦福大学）；Department of Physics, Stanford University（斯坦福大学物理系）；Kavli Institute for Particle Astrophysics and Cosmology, Stanford University（斯坦福大学卡弗里粒子天体物理学与宇宙学研究所）
Testing Magnetic Field Configurations in Spider Pulsar PSR J1723-2837 with IXPE
Louisiana State University（路易斯安那州立大学）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；Stanford University（斯坦福大学）；Columbia University（哥伦比亚大学）；University of Maryland, College Park（马里兰大学帕克分校）；Center for Research and Exploration in Space Science and Technology, NASA/GSFC（NASA/戈达德太空飞行中心空间科学与技术研究探索中心）；University of Maryland, Baltimore County（马里兰大学巴尔的摩县分校）
X-ray polarization of Z-type neutron star low-mass X-ray binaries -- I. Model-independent, time-resolved X-ray polarimetry
Università degli Studi Roma Tre（罗马第三大学）；INAF – Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所）；INAF – Osservatorio Astronomico di Cagliari（意大利国家天体物理研究所卡利亚里天文台）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio（意大利国家天体物理研究所空间科学天文台）
X-ray Polarimetry in the Low Statistics Regime using the Bayesian Approach Reveals Polarization Angle Variations
State Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences（高能物理研究所粒子天体物理国家重点实验室）；University of Chinese Academy of Sciences（中国科学院大学）；University of Turku（图尔库大学）
Fitting XMM-Newton Observations of the AXP 1RXS J170849.0-400910 with four magnetar surface emission models, and predictions for X-ray polarization observations with IXPE
A Pipeline for the AI-Assisted Analysis of Imaging X-ray Polarimetry Explorer Observations of Black Hole X-ray Binaries and Limits on Their Polarization Variability
Washington University in St. Louis（华盛顿大学圣路易斯分校）；Washington University in St. Louis McDonnell Center for the Space Sciences and Center for Quantum Leaps（华盛顿大学圣路易斯分校麦克唐纳空间科学中心与量子跃迁中心）
Discovery of Strong Energy-Dependent X-ray Polarization in the Intermediate State of GS 1354-64
Massachusetts Institute of Technology（麻省理工学院）；INAF Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所）；Center for Astrophysics | Harvard & Smithsonian（哈佛史密松尼天体物理中心）；Scuola Universitaria Superiore IUSS Pavia（帕维亚高等大学）；McGill University（麦吉尔大学）；Villanova University（维拉诺瓦大学）
X-ray polarization of the Compton-thin Seyfert galaxy NGC 5506 with IXPE
Università degli Studi Roma Tre（罗马第三大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata”（意大利国家核物理研究所罗马“托尔维加塔”分部）；NASA Marshall Space Flight Center（美国国家航空航天局马歇尔太空飞行中心）；Agenzia Spaziale Italiana（意大利航天局）；INAF - Osservatorio astronomico di Roma（意大利国家天体物理研究所罗马天文台）；Clemson University（克莱姆森大学）；INAF-Osservatorio Astronomico di Brera（意大利国家天体物理研究所布里埃拉天文台）
IXPE Polarizations of the Lighthouse Pulsar, Trail, and Filament
Stanford University（斯坦福大学）；The University of Hong Kong（香港大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Pisa（意大利国家核物理研究所，比萨分部）；The George Washington University（乔治华盛顿大学）；INAF Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）；Università degli Studi di Firenze（佛罗伦萨大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Firenze（意大利国家核物理研究所，佛罗伦萨分部）
