KMS of Xinjiang Astronomical Observatory, CAS
| 利用甚长基线干涉阵研究超大质量双黑洞 | |
| Alternative Title | Study of supermassive binary black holes with VLBI |
杨小龙
| |
| Subtype | 博士 |
| Thesis Advisor | 刘祥 |
| 2017 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 天体物理 |
| Keyword | 甚长基线干涉 活动星系核 超大质量双黑洞 星系:Ngc 5252 类 星体:Pks 1155+251 |
| Abstract | 本文共分为两个部分，第一部分为背景和方法简介，主要包括AGN简介和星系的并合过程，此外还对甚长基线干涉技术做了简要介绍。第二部分详细介绍了我们利用甚长基线干涉方法发现的两个双黑洞候选体，包括通过EVN在NGC 5252星系中发现的一个超大质量双黑洞对，利用VLBA对一个双黑洞候选体PKS 1155+251的K波段和扑波段观测研究，这一部分重点讨论甚长基线干涉阵的观测申请，数据处理和结果分析。 极亮X射线源（ULXs)是指2-10keV能段的X射线光度超过1039erg/s的一类天体，这种天体通常在偏离星系中心的位置发现。目前对于ULX的高X射线光度主要有两种解释，一种解释认为不超过爱丁顿极限，但ULXs为恒星质量的黑洞，另一种解释坚持爱丁顿极限认为ULXs的中央引擎为中等质量黑洞。目前还没有完全的证据证明这两种解释哪一种更占上风。大多数ULXs中的确发现了恒星质量的对应体，但是也有几个被称为HLX的极亮X射线源的X射线光度达到1040 erg/s甚至达到1043erg/s，对于这类源很难用恒星质量的黑洞解释。CXOJ1338+0432是最近发现的一个位于NGC 5252星系边缘的一个ULX，被认为是一个中等质量的黑洞。 我们通过EVN成功探测到了这个源，我们发现此CXO J1338+0432拥有很高的射电 亮温度，达到108K，同时，我们利用EVN的数据和MERLIN的数据计算了谱指数， 发现其具有平谱(a = -0.1)，与一般的AGN射电核相似。通过黑洞基本面关系，我 们利用EVN 1.4GHz的数据和X射线数据计算了黑洞质量，结果显示这个黑洞质量与位于星系中央的超大质量黑洞达到相同量级。此外通过对比OIII线和X射线特征，我们发现这个超大质量黑洞与在低红移的低光度活动星系核(LLAGN)类似，因此我们将CXO J1338+0432重新证认为低光度的活动星系核。由于NGC 5252星系中央本身存在一个超大质量的黑洞，因此，CXOJ1338+0432与NGC 5252星系中央超大质量黑洞共同组成了双黑洞系统。 第四章重点分析了利用美国甚长基干涉阵(VLBA)对双黑洞候选体PKS 1155+251 的K波段和扑波段观测。这个源在低频显示一个很亮的组分，因此最初在低频数据中最亮的组分被证认为核。但是接下来的X波段和U波段数据显示中心存在一个平谱的成分，而原来被证认为核的最亮组分相比而言呈现陡谱，因此中心平谱组分被重新证认为核，这个源被认为是个致密对称源（CSO)。我们VLBA K波段和Q波段的数据得到了不同的结果，我们的结果显示，最亮的成分和中央成分都为平谱，而且中央组分和最亮组分都拥有很高的亮温度。我们的高频VLBA数据使得我们重新证认这颗源为双黑洞候选体。今后还需要更多观测来进行交叉证认它是否真的是一个双黑洞系统。 |
| Other Abstract | This paper is mainly made up with two parts. The hrst part is the introduction of background and methods, including the introduction of AGN, the merger process of galaxies, and furthermore, Very Long Baseline Interferometry (VLBI) technology. The second part introduces the binary black hole candidates that we found by the VLBI approach, including a dual AGN in the galaxy NGC 5252 which revealed using European VLBI Network (EVN), and a binary black hole candidate PKS 1155+251 at K band and Q band observed with Very Long Baseline Array (VLBA), in this part, we focus on discussing the application of VLBI array, data processing and analysis. The Ultra Luminous X-ray Sources (ULXs) are a class of objects with the X-ray luminosity exceeding 1039 erg/s at 2-10 keV, which is usually found in the non-nuclei region of its host galaxy. There are two explanations for the high X-ray luminosity of ULXs, the one is that ULX belongs to the stellar mass black holes but with super Eddington accretion rate, another explanation insists Eddington limit and allocates ULX is the object whose central engine is intermediate mass black hole. There are no complete evidence to show which of the two explanations is more advantageous. Most ULXs did hnd the corresponding stellar mass black hole nature, but there are a few known as HLXs which X-ray luminosity reached 1040 erg/s or even 1043 erg/s, for this type of sources which are difficult to explain with the stellar mass black hole. CXO J1338+0432 is a recently discovered ULX, located at the outskirts of the Seyfert galaxy NGC 5252, which is considered to be an intermediate massive black hole. We successfully detected this source using the EVN, we found that the CXO J1338+0432 has a very high radio brightness temperature, up to 108 K, at the same time, we used the EVN data and MERLIN data to estimate its spectral index, the result shows a flat spectrum (a= -0.1) for CXO J1338+0432, this spectral index consistents with the radio core of normal AGN. The black hole fundamental plane relation was hired to estimate the black hole mass. We used our EVN 1.4 GHz data and X-ray data to estimate the black hole mass, the result suggests a supermassive black hole mass. By comparing the characteristics of the OIII line and the X-ray properties, we find that this source is similar with the low luminosity active galactic nucleus (LLAGN) found in the low redshifted galaxies, so we re-identified CXO J1338+0432 as a supermassive black hole. There is also a supermassive black hole in the center of the NGC 5252 galaxy, so together with the CXO J1338+0432 form a dual radioactive supermassive black hole system. The fourth chapter we introduce the VLBA observations of binary black hole candidate PKS 1155+251 at K band and Q band. This source shows a very bright component at the low frequency, and the brightest component in the low frequency data was considered as the core. But the next X band and U band high resolution data show that there is a flat spectral component at the center of the source, while the brightest core component shows a steep spectrum, so the center of flat spectral component was re-identified as core, this source was classified as a CSO. We carried out even higher resolution observations at K band and Q band using VLBA, our data get different results. The K band and Q band data show that the brightest southern component and the central component are both show flat spectrum. The central component and brightest component have very high brightness temperatures. This result of high frequency VLBA observations allows us to provide a binary black hole explanation that the both nuclei are radioactive. Further observation and cross identification are needed in confirming the binary black hole nature. |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xao.ac.cn/handle/45760611-7/1702 |
| Collection | 研究生学位论文 射电天文研究室 |
| Affiliation | 中国科学院新疆天文台 |
| Recommended Citation GB/T 7714 | 杨小龙. 利用甚长基线干涉阵研究超大质量双黑洞[D]. 北京. 中国科学院大学,2017. |
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| File Name/Size | DocType | Version | Access | License | ||
| 2017届博士学位论文-杨小龙.pdf（6458KB） | 暂不开放 | CC BY-NC-SA | Application Full Text | |||
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