GPS射电源的光谱观测研究

发布时间：2018-04-18 11:26

本文选题：GPS源 + 活动星系核　；参考：《云南大学》2015年硕士论文

【摘要】：GPS源(Gigahertz-peaked spectrum sources)是一类射电结构非常致密的射电噪活动星系核(AGN),它们的射电谱峰值频率在1GHz左右。GPS源的射电结构线尺度一般在1kpc以内。一般认为GPS源是年轻的射电噪AGN,喷流活动形成不久。根据高分辨率射电结构确定的动力学年龄为几百到几千年不等,喷流因此还没有足够的时间向外发展,但随着时间最后会演化为大尺度的射电星系。因此,对这些源的研究有利于研究AGN活动性的产生、AGN的演化、AGN的吸积和喷流之间的关系等AGN领域的众多核心问题。目前,GPS源的研究主要集中在射电波段,缺少光学等其它波段的研究,很多GPS源的红移未知。本文的工作主要是挑选出一个GPS源样本,使用丽江2.4光学望远镜对样本中的每颗源进行光谱观测,同时结合已有的SDSS和其他望远镜的光谱观测,从光学波段对这些射电源进行细致的研究。本文对AGN、GPS源和AGN光谱的相关背景做了介绍。利用丽江2.4米光学望远镜对研究样本中的每一颗源进行光谱观测,使用IRAF进行光谱数据处理,并将处理出来的最终光谱与SDSS和文献中同一颗GPS源光谱进行对比分析。我们发现GPS源星系在不同时间的光谱基本上没有变化,这与星系喷流视角较大,光变不剧烈的说法一致。而GPS源类星体Mrk0668在不同时间的光谱有明显变化,我们认为这可能是光变引起的。通过证认研究样本中未知红移源MG1J180356+0340光谱中AGN特征发射线和吸收线,初步确定MG1J180356+0340的红移为0.14。通过光谱拟合和测量连续谱和发射线参数(L和FWHM),我们确定了研究样本中Mrk0668、HB891127-145和CGRaBSJ1424+2256这三颗源的中心黑洞质量,并对它们的吸积模式进行了分析。我们发现Mrk0668的吸积模式可能处于ADAF和标准盘的过渡期,而HB891127-145和CGRaBS J1424+2256的吸积模式可能是高吸积率的slim盘主导。我们还对Mrk0668的在不同时间的光谱变化进行了分析。通过比较拟合测量不同时间光谱的谱指数、连续谱5100A处和发射线[OIⅢ]λ5007的流量,我们发现它的谱型变化较小,而连续谱5100A流量变化较大。通过对比谱指数和连续谱5100A流量,我们发现Mrk0668像大多数类星体一样具有越亮越蓝的趋势(bluer-when-brighter trend:BWB)。为了更好的理解AGN宽线区的物理过程,我们还使用光致电离模拟代码Cloudy模拟了AGN宽线区的辐射能谱,模拟结果与Ghisellini的结果一致。
[Abstract]:Gigahertz-peaked spectrum source is a class of radio noise active galactic nuclei (AGNN) with very compact radio structure. Their radio spectrum peak frequency is generally within 1kpc.GPS sources are generally considered to be young AGNs with jet activity forming shortly.The dynamic ages determined according to the high resolution radio structure range from several hundred to several thousand years, so the jet does not have enough time to develop outwards, but over time it will eventually evolve into a large scale radio galaxy.Therefore, the study of these sources is beneficial to the study of the evolution of AGN activity and the relationship between accretion and jet flow in AGN.At present, the research of GPS source is mainly focused on radio wave band, but lack of optical and other bands, many GPS sources are unknown redshift.The main work of this paper is to select a sample of GPS source, and use Lijiang 2.4 optical telescope to carry out spectral observation of each source in the sample, and combine the spectral observation of existing SDSS and other telescopes.These radio sources are studied in detail from the optical band.This paper introduces the background of AGN source and AGN spectrum.Using Lijiang 2.4m optical telescope, the spectrum of each source in the study sample is observed, the spectral data is processed by IRAF, and the final spectrum is compared with the spectrum of SDSS and the same GPS source in the literature.We find that the spectra of GPS source galaxies are basically unchanged at different times, which is consistent with the theory that the galactic jet has a larger angle of view and less intense light change.The spectra of GPS source quasar Mrk0668 have obvious changes at different time, which we think may be caused by light change.The AGN characteristic emission line and absorption line in the MG1J180356 0340 spectrum of unknown red-shift source in the sample were identified and the red shift of MG1J180356 0340 was determined to be 0.14.By means of spectral fitting and measurement of the continuous spectrum and emission line parameters L and FWHM, we have determined the mass of the central black hole of Mrk0668 / HB891127-145 and CGRaBSJ1424 2256, and analyzed their accretion models.We find that the accretion mode of Mrk0668 may be in the transition period between ADAF and standard disk, while the accretion mode of HB891127-145 and CGRaBS J1424 2256 may be dominated by slim disk with high accretion rate.We also analyzed the spectral changes of Mrk0668 at different time.By comparing and fitting the spectral exponents of different time spectra, the flux at 5100A of continuous spectrum and 位 5007 of emission line [OI 鈪 位 5007, we find that the variation of spectral type is relatively small, while the flux of continuous spectrum 5100A changes greatly.By comparing spectral exponents with 5100A continuous spectra, we find that Mrk0668, like most quasars, has a bluer-whenever bright trend: BWBN trend.In order to better understand the physical process of the wide line region of AGN, we also use the photoionization simulation code Cloudy to simulate the energy spectrum of the wide line region of AGN. The simulation results are consistent with the results of Ghisellini.
【学位授予单位】：云南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P161;P157.6

【共引文献】