A. Tarana, F. Capitanio, A. Gnarini, S. Fabiani, F. Ursini, S. Bianchi, C. Ferrigno, M. Parra, M. Cocchi, R. Farinelli, G. Matt, P. Soffitta, A. Bobrikova, P. Kaaret, M. Ng, J. Poutanen, S. Ravi
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Moreover, these observations suggest a relatively low-inclination system (23° < <i>i<i/> < 46°) with a weak reflection component, consistent with emission from the accretion disk and neutron star boundary layer. Spectro-polarimetric analysis reveals no significant polarization in the 2–8 keV range, with a 3<i>σ<i/> level upper limit on the polarization degree of 1.9%. However, marginal evidence of polarization is detected in the 2–3 keV band at the 95.5% confidence level (2<i>σ<i/>), suggesting potential contributions from scattering effects in the individual spectral components (disk, reflection, and Comptonization) that may cancel each other out due to the different orientations of their polarization angles. 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引用次数: 0
摘要
我们利用成像x射线偏振探测器(IXPE)的数据,以及同时进行的NuSTAR、NICER和INTEGRAL观测,对弱磁化中子星低质量x射线双星GX 9+1进行了x射线光谱偏振研究。GX 9+1位于银河系凸起,是一个持续明亮的环礁源,以其在彩色图上的光谱变化而闻名。我们在软态期间的光谱分析证实,发射主要由软黑体和热复合成分主导,没有硬x射线尾巴的证据。此外,这些观测结果表明,相对低倾角系统(23°< i σ水平)的极化度上限为1.9%。然而,在95.5%的置信水平(2σ)上,在2-3 keV波段检测到偏振的边缘证据,这表明单个光谱成分(盘状、反射和复合)的散射效应可能会由于其偏振角的不同方向而相互抵消。这种行为与IXPE观察到的其他环礁源一致,与z级源相比,它们通常表现出更低和更少的可变偏振度。
X-ray spectro-polarimetry analysis of the weakly magnetized neutron star X-ray binary GX 9+1
We present an X-ray spectro-polarimetric study of the weakly magnetized neutron star low-mass X-ray binary GX 9+1, utilizing data from the Imaging X-ray Polarimetry Explorer (IXPE), alongside simultaneous NuSTAR, NICER, and INTEGRAL observations. GX 9+1, located in the Galactic bulge, is a persistently bright atoll source known for its spectral variability along the color–color diagram. Our spectral analysis during the soft state confirms that the emission is dominated by a soft blackbody and thermal Comptonization components, with no evidence of a hard X-ray tail. Moreover, these observations suggest a relatively low-inclination system (23° < i < 46°) with a weak reflection component, consistent with emission from the accretion disk and neutron star boundary layer. Spectro-polarimetric analysis reveals no significant polarization in the 2–8 keV range, with a 3σ level upper limit on the polarization degree of 1.9%. However, marginal evidence of polarization is detected in the 2–3 keV band at the 95.5% confidence level (2σ), suggesting potential contributions from scattering effects in the individual spectral components (disk, reflection, and Comptonization) that may cancel each other out due to the different orientations of their polarization angles. This behavior aligns with other atoll sources observed by IXPE, which typically exhibit lower and less variable polarization degrees compared to Z–class sources.
期刊介绍:
Astronomy & Astrophysics is an international Journal that publishes papers on all aspects of astronomy and astrophysics (theoretical, observational, and instrumental) independently of the techniques used to obtain the results.