利用次毫米陣列研究天鵝座A超大質量黑洞之吸積流

Studies of the Accretion Flow onto the Supermassive Black Hole of Cygnus A with Submillimeter Array

羅文斌(Wen-Ping Lo)

指導教授 ： 朱有花

共同指導教授 ： 淺田圭一(Keiichi Asada)

國立臺灣大學/理學院/物理學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602918

摘要

測量超大質量黑洞鄰近之吸積率，可以由觀測上給出對於吸積流模型之限制，也能探討相對論性噴流的動力機制。此論文聚焦於低亮度活躍星系核(low-luminosity active galactic nuclei)，其低亮度被視為是由於其超大質量黑洞之吸積流為低輻射效率。藉由次毫米波陣列望遠鏡測量了天鵝座A 之核心在毫米波段之偏振輻射。在此觀測中，基於天鵝座A 之偏振性質在統計上缺乏有效之測量值，藉由去偏振化機制、軔致輻射吸收之探討及半解析平流主導吸積流光譜能量分佈之擬和，計算出旋轉量(rotation measure)、吸積率(the mass accretion)、以及吸積功率(accretion power) 之觀測下限值。並由此觀測得到排除對流主導吸積流模型之結論。

關鍵字

超大質量黑洞 ； 吸積率 ； 天鵝座A ； 去偏振化機制 ； 次毫米陣列 ； 法拉第旋轉 ； 輻射不顯著吸積流 ； 低亮度活躍星系核

並列摘要

Unveiling the nature of accretion process onto the supermassive black hole (SMBH) is one of the primary purposes in modern high energy astrophysics. Constraining mass accretion rate (M ̇ ) can not only clarify the features of in- flow but also connect to the dynamics of outflow. In this dissertation, we concentrate on the low-luminosity active galactic nuclei (LLAGN) of Cygnus A, which are thought to be powered by radiatively inefficient accretion flow (RIAF). Faraday rotation measure (RM), the tracer of plasma density, pro- vides a powerful tool that can be used to investigate the mass accretion rate near the SMBH of LLAGN. We present the polarimetric observation results towards Cygnus A utilizing Submillimeter Array at 230 GHz and obtain the observational constraint on RM. With the scenarios of beam/bandwidth de- polarization and advection-dominated accretion flow model fitting, the mass accretion rate and the accretion type of Cygnus A can be constrained, and the convection-dominated accretion flow solution is excluded.

並列關鍵字

Supermassive Black Hole ； Cygnus A ； Beam Depolarization ； Submillimeter Array ； Faraday Rotation Measure ； Radiatively-Inefficient Accretion Flow ； Low-Luminosity Active Galactic Nuclei

參考文獻

M. A. Abramowicz and P. C. Fragile. Foundations of Black Hole Accretion Disk Theory. Living Reviews in Relativity, 16, 2013. ISSN 1433-8351. doi: 10.12942/lrr-2013-1. URLhttp://adsabs.harvard.edu/abs/2013LRR....16....1A.

S. W. Allen, R. J. H. Dunn, A. C. Fabian, G. B. Taylor, and C. S. Reynolds. The relation between accretion rate and jet power in X-ray luminous elliptical galaxies. Monthly Notices of the Royal Astronomical Society, 372(1):21–30, 2006. ISSN 00358711. doi: 10.1111/j.1365-2966.2006.10778.x.

F. K. Baganoff, Y. Maeda, M. Morris, M. W. Bautz, W. N. Brandt, W. Cui, J. P. Doty, E. D. Feigelson, G. P. Garmire, S. H. Pravdo, G. R. Ricker, and L. K. Townsley. Chandra X Ray Spectroscopic Imaging of Sagittarius A* and the Central Parsec of the Galaxy. The Astrophysical Journal, 591(2):891–915, 7 2003. ISSN 0004-637X. doi: 10.1086/ 375145. URL http://adsabs.harvard.edu/abs/2003ApJ...591..891B.

R. D. Blandford and M. C. Begelman. On the fate of gas accreting at a low rate on to a black hole. Mnras, 303:L1–L5, 1999. ISSN 0035-8711. doi: 10.1046/j.1365-8711. 1999.02358.x.

R. D. Blandford and R. L. Znajek. Electromagnetic extraction of energy from Kerr black holes. Monthly Notices of the Royal Astronomical Society, 179(3):433–456, 7 1977. ISSN 0035-8711. doi: 10.1093/mnras/179.3.433. URL http://adsabs.harvard.edu/ abs/1977MNRAS.179..433B.