NEAR-INFRARED POLARIMETRY OF FLARES FROM Sgr A* WITH SUBARU/CIAO
NEAR-INFRARED POLARIMETRY OF FLARES FROM Sgr A* WITH SUBARU/CIAO
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DOI：
10.1088/0004-637x/702/1/l56
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发表时间：
2009-07
期刊：
影响因子：
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通讯作者：
S. Nishiyama;M. Tamura;H. Hatano;T. Nagata;T. Kudo;M. Ishii;R. Schödel;A. Eckart
中科院分区：
文献类型：
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作者：
S. Nishiyama;M. Tamura;H. Hatano;T. Nagata;T. Kudo;M. Ishii;R. Schödel;A. Eckart
我们已经进行了近红外（NIR）监测观测的Sgr A*，银河系中心的无线电源与超大质量黑洞，与近红外相机CIAO和36元素的自适应光学系统的斯巴鲁望远镜。在2008年5月28日的220分钟监测中，我们观测到三个KS波段（2.15 μm）的耀斑，并证实耀斑发射是高度偏振的，支持近红外发射的同步辐射性质。偏振度和偏振位置角也有明显的变化：在耀斑下降阶段，偏振度增加约20%，偏振位置角摆动约60° ~ 70 °。通量与偏振度之间的相关性可以通过来自绕Sgr A* 运行的热点的耀斑发射来很好地解释。与文献中的计算比较，给出了对围绕Sgr A* 的热点轨道的倾角i的约束，因为45° θ i < 90°（接近边缘）。
We have performed near-infrared (NIR) monitoring observations of Sgr A*, the Galactic center radio source associated with a supermassive black hole, with the NIR camera CIAO and the 36 element adaptive optics system on the Subaru telescope. We observed three flares in the KS band (2.15 μm) during 220 minutes monitoring on 2008 May 28, and confirmed the flare emission is highly polarized, supporting the synchrotron radiation nature of the NIR emission. Clear variations in the degree and position angle of polarization were also detected: an increase of the degree of polarization of about 20%, and a swing of the position angle of ∼60°–70° in the declining phase of the flares. The correlation between the flux and the degree of polarization can be well explained by the flare emission coming from hotspot(s) orbiting Sgr A*. Comparison with calculations in the literature gives a constraint to the inclination angle i of the orbit of the hotspot around Sgr A*, as 45° ⩽ i < 90° (close to edge-on).