活动星系核的射电和光学IDV观测研究
文献类型：学位论文
| 作者 | 林明权
|
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘祥 |
| 关键词 | 活动星系核 日变源 射电-光学观测 星际闪烁 |
| 学位专业 | 天体物理 |
| 中文摘要 | 短时标光变（包括日变源，即IDV）是研究活动星系核辐射区的内部物理条件、结构变化和辐射过程的变化重要探针之一。根据观测研究发现，大约有30% ∼ 50% 平谱射电源有IDV。对于IDV的起因，主要有两类：一类是源内禀的，另外一类是源外禀的。用源的内禀机制来解析IDV现象会导致源的亮温度远超过逆康普顿亮温度，所以现在常用星际闪烁模型解析IDV变化。但是在 利用星际闪烁模型解析IDV变化时，源结构的变化也是不可忽略的，因为观测到的流量变化一般可能是星际闪烁和源内部变化叠加的效果。所以研究活动星系核的IDV光变，对研究星际闪烁，以及限制其中心区域的理论模型都有重要作用。 本论文介绍了IDV观测的仪器、观测方法、数据处理和分析方法。对南山25m射电望远镜在1.3cm波段的IDV观测进行了数据分析与研究。对南山25m射电望远镜与山东大学威海天文台1m光学望远镜同步联测的BL Lacertae数据进行了射电和光学的IDV分析研究。对0716+714和1156+295进行了星际闪烁模型拟合并对模型进行了改进。对几个费米爆发源在射电波段进行了数据分析。 利用南山25m射电望远镜对26个射电源进行了1.3cm波段的IDV观测，在置信度为99%的情况，探测到六个IDV源，它们分别是分别为：J0136+4751,J0217+0144, J1058+0133, J1751+0939, J1833+2103和DA193。尽管在整个观测过程中天气一直很好，但系统噪声较大（1.58%），造成系统噪声较大的一个原因可能是每个源的点数较少。 利用南山25m射电望远镜和威海天文台1m光学望远镜，对几个AGN进行了射电与光学的IDV研究。在射电波段，对BL Lacertae 通过 2r 检验，两次联测都探测到了IDV变化，且比较剧烈。在光学波段，通过C检验和F检验来探测BL Lacertae是否具有微光变。探测结果与射电波段不完全一致，但流量变化趋势一致。对BL Lacertae进行了准同时V-R和R-I的色指数分析，该源只在2013.10.18-2013.10.19那次观测的色指数分析中出现“越暗越红”的现象，对于2013.09.01-2013.09.03这次观测的色指数分析不存在明显的线性关系。尽管在射电和光学波段对于IDV探测的结果不完全一致，但是流量在射电和光学的变化具有一致性。通过射电和光学波段的相关分析，在短时标分析上可能具有强的相关性，但这有待进一步验证。 利用最小二乘法对光变时标具有年周期调制的源进行各向异性星际闪烁模型（ISS）拟合，可以得到际闪烁介质云的距离（在几百秒差距以内）等效散射屏与观测者的相对速度。同时还对各向异性星际闪烁模型进行了改进，将原来认为设定的源的角大小设为未知数，改进后的模型得到与观测值符合的拟合结果，但在精度上没有明显的提高。 |
| 英文摘要 | Intra-Day Variability (IDV) provides a powerful probe not only for microarcsecond scale structures of AGNs but also for the interstellar median properties. According to the statistics, about 30%∼50% of the compact flat-spectrum radio sources show IDV. The causes of the IDV are mainly due to two kinds: the source intrinsic and source extrinsic. The source intrinsic explanation always leads to the brightness temperature of the source far exceeding the inverse-Compton limit. So the IDV often is explained by the ISS models.However, the change in source structure cannot be ignored when using the ISS model to explain the IDV because the source intrinsic also contributes to the IDV variability.Therefore, IDV provides strong constraints for both models of ISS and AGN. In this thesis, the IDV observation instrument,the methods of monitoring,the data reduction and the methods of analysis were introduced.The data analysis and research for the pilot 1.3cm IDV observation of Nanshan 25m radio telescope were carried out. Simultaneous Radio-Optical Intraday Variability Observation and study of AGN were also carried out using NanShan 25m radio telescope, NanShan 1m Large Field optical telescope and WeiHai 1m optical telescope. Radio and optical IDV analysis of BL Lacertae were performed. ISS model fitting to the sources 0716+714 and 1156+295, with corresponding modifications to the ISS model, were carried out. The data analysis of several Fermi eruptive variables at 4.8GHz was carried out. A pilot IDV observations at 1.3 cm wavelength for 26 AGNs at Urumqi were carried out. Six sources, namely J0136+4751, J0217+0144, J1058+0133, J1751+0939, J1833-2103 and DA193, were detected as IDV sources at 99% confidence level. The weather was fine throughout the observation but the system noise remains large after calibration . The system noise could be due to the large number of sources involved in the observation causing sparsity of data points for each sources. The simultaneous radio and optical IDV observation for a few AGNs were carried out through NanShan 25m radio telescope and WeiHai 1m optical telescope. Through 2r test, the BL Lacertae shows relatively intense IDV variability at 4.8GHz. The C-test and F-test were applied to examine the IDV for BL Lacertae. Quasisimultaneous V-R and R-I color indices of BL Lacertae were analyzed. The results show that BL Lacertae only behaves a bluer when brighter behavior for the second epoch (2013.10.18-2013.10.19),and first epoch (2013.09.01-2013.09.03) color indices analysis didn’t show obvious linear relationship. Although the optical IDV result is not exactly the same as radio, their trend of flux variability at the two bands is similar. Through the correlation analysis between radio and optical bands, there may be exit strong correlation on the short timescales, but need further verification. Using the least squared fitting of the anisotropic ISS model to the IDV timescales of 0716+714 and 1156+295, in order to obtain the ISS screen distance, the screen velocity relative to observers. Also to set the source angular size as an unknown parameter in the anisotropic ISS model, the fitting result is similar, but the precision is not obviously improved. |
| 语种 | 中文 |
| 公开日期 | 2014-12-04 |
| 源URL | [http://ir.xao.ac.cn/handle/45760611-7/385]  |
| 专题 | 研究生 新疆天文台_射电天文研究室 |
| 推荐引用方式 GB/T 7714 | 林明权. 活动星系核的射电和光学IDV观测研究[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：新疆天文台
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