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arXiv 2002.09691astro-ph.HE
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黑洞瞬变源MAXI J1820 +070的软态:来自坍落区边缘的辐射?

The Soft State of the Black Hole Transient Source MAXI J1820+070: Emission from the Edge of the Plunge Region?

A. C. Fabian, D. J Buisson, P. Kosec, C. S. Reynolds, D. R. Wilkins, J. A. Tomsick, D. J. Walton, P. Gandhi, D. Altamirano, Z. Arzoumanian, E. M. Cackett, S. Dy… 展开作者

A. C. Fabian, D. J Buisson, P. Kosec, C. S. Reynolds, D. R. Wilkins, J. A. Tomsick, D. J. Walton, P. Gandhi, D. Altamirano, Z. Arzoumanian, E. M. Cackett, S. Dyda, J. A. Garcia, K. C. Gendreau, B. W Grefenstette, F. A. Harrison, J. Homan, E. Kara, R. M. Ludlam, J. M. Miller, J. F. Steiner

摘要:

银河系黑洞X射线双星MAXI J1820+070在2018年发生了一次明亮的爆发,当时它成为天空中第二亮的X射线源。对于XMM-牛顿和钱德拉等X射线CCD仪器来说,它太亮了,但NICER和NuSTAR等光子计数仪器可以很好地观察到。我们在这里报告的软状态期间发现的过量排放组件。除了常规的圆盘发射外,最好用黑体光谱建模,建模为diskbb或kerrbb。它的温度变化从约0.9至1.1千电子伏,这是约30%至80%,高于内部盘的diskbb温度。它的流量在圆盘流量的4%到12%之间变化。对磁化吸积盘的模拟已经预测了与黑洞周围的最内稳定圆轨道(ISCO)处的非零扭矩相关的过量发射的可能性,根据其他NuSTAR研究,该轨道位于约5个引力半径或约60公里处(对于质量为8 M的黑洞)。在这种情况下,ISCO的发射区的宽度在1.3到4.6公里之间变化,并将包括物质开始自由落入黑洞的暴跌区的开始。

英文摘要:

The Galactic black hole X-ray binary MAXI J1820+070 had a bright outburst in 2018 when it became the second brightest X-ray source in the Sky. It was too bright for X-ray CCD instruments such as XMM-Newton and Chandra, but was well observed by photon-counting instruments such as NICER and NuSTAR. We report here on the discovery of an excess emission component during the soft state. It is best modelled with a blackbody spectrum in addition to the regular disk emission, modelled either as diskbb or kerrbb. Its temperature varies from about 0.9 to 1.1 keV which is about 30 to 80 per cent higher than the inner disc temperature of diskbb. Its flux varies between 4 and 12 percent of the disc flux. Simulations of magnetised accretion discs have predicted the possibility of excess emission associated with a non-zero torque at the Innermost Stable Circular Orbit (ISCO) about the black hole, which from other NuSTAR studies lies at about 5 gravitational radii or about 60 km (for a black hole mass is 8 M). In this case the emitting region at the ISCO has a width varying between 1.3 and 4.6 km and would encompass the start of the plunge region where matter begins to fall freely into the black hole.

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