We present recent improvements in polarization analysis with the INTEGRAL SPI data. The SPI detector plane consists of 19 independent Ge crystals and can operate as a polarimeter. The anisotropy characteristics of Compton diffusions can provide information on the polarization parameters of the incident flux. By including the physics of the polarized Compton process in the instrument simulation, we are able to determine the instrument response for a linearly polarized emission at any position angle. We compare the observed data with the simulation sets by a minimum χ^2 technique to determine the polarization parameters of the source (angle and fraction). We have tested our analysis procedure with Crab nebula observations and find a position angle similar to those previously reported in the literature, with a comfortable significance. Since the instrument response depends on the incident angle, each exposure in the SPI data requires its own set of simulations, calculated for 18 polarization angles (from 0° to 170° in steps of 10°) and unpolarized emission. The analysis of a large amount of observations for a given source, required to obtain statistically significant results, represents a large amount of computing time, but it is the only way to access this complementary information in the hard X-ray regime. Indeed, major scientific advances are expected from such studies since the observational results will help to discriminate between the different models proposed for the high energy emission of compact objects like X-ray binaries and active galactic nuclei or gamma-ray bursts.
A Large-Area Optical Time Projection Chamber for Hard X-ray Polarimetry with Directional Imaging of Low-Energy Electron Recoils
Gran Sasso Science Institute（格兰萨索科学研究所）；INFN Laboratori Nazionali del Gran Sasso（意大利国家核物理研究所大萨索国家实验室）；INFN Laboratori Nazionali di Frascati（意大利国家核物理研究所弗拉斯卡蒂国家实验室）；IAPS - INAF Istituto di Astrofisica e Planetologia Spaziali（空间天体物理学和行星学研究所-意大利国家天体物理研究所）
Instruments for Focal Plane X-Ray Polarimetry in the Next Decade
Istituto Nazionale di Astrofisica - Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所-天体物理学与行星科学研究所）；Thales Alenia Space Italia S.p.A.（泰雷兹阿莱尼亚太空意大利公司）；Deutsches Elektronen-Synchrotron DESY（德国电子同步辐射中心）；Physical Research Laboratory（物理研究实验室）
Hard X-Ray Focal-Plane Compton Spectro-Polarimeter: Detector Development and Sensitivity Evaluation
Physical Research Laboratory（物理研究实验室）；INAF-IAPS（意大利国家天体物理研究所-空间天体物理研究所）；Kavli Institute of 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）
Combining angular differential imaging and accurate polarimetry with SPHERE/IRDIS to characterize young giant exoplanets
年轻的巨大系外行星发出的红外辐射可以被线性偏振到百分之几。这种线性偏振可以追踪：1）大气云和霾层的存在，2）空间结构，例如云带和旋转扁平化，3）自旋轴方向和4）颗粒大小和云顶压力。我们介绍了一种新的高对比度的成像方案，结合角度差分成像（ADI）和精确的近红外偏振来表征自发光的巨型系外行星。我们在VLT/SPHERE-IRDIS上实现了这一技术，并开发了相应的观测策略、偏振校正和数据处理方法。通过结合ADI和偏振测量，我们可以表征行星，可以直接成像具有非常高的信噪比。我们使用IRDIS的光瞳跟踪模式，并结合ADI和主成分分析，以减少斑点噪声。我们利用IRDIS的双光束偏振模式来消除严重限制偏振灵敏度的差分效应（平场误差、差分像差和视宁度），从而进一步抑制斑点噪声。为了纠正仪器的偏振效应，我们应用一个详细的米勒矩阵模型，描述了望远镜和仪器，并具有绝对的偏振精度$\leq0.1\%$。使用这种技术，我们已经观察到HR 8799的行星和（亚恒星）伴星PZ Tel B。不幸的是，我们在第一次分析中没有检测到偏振信号。我们估计初步$1σ$的$\sim1\%$和$\sim0.1\%$的HR 8799和PZ Tel B的行星的线性偏振度的上限。所实现的低于百分之一的灵敏度和准确度表明，我们的技术在通过直接成像偏振测量来表征系外行星方面具有巨大的前景。
