基于Fermi-LAT数据的球状星团研究

发布时间：2018-05-31 01:31

本文选题：球状星团 + 脉冲星　；参考：《云南大学》2016年博士论文

【摘要】：球状星团主要是由大量的低金属丰度的年老恒星(特征年龄100亿年)组成的球状的自引力束缚系统。迄今为止,银河系内已经发现了158个球状星团。2008年之前人们对这类源只探测到光学和射电辐射。Fermi卫星成功发射后,球状星团的伽马射线辐射被成功探测,进而被确认为是一类新的伽马射线辐射源。由于大部分球状星团的纬度低,受银盘的弥漫背景伽马射线辐射的影响显著,因此认证困难。迄今为止,伽马射线球状星团的数目极其有限。为了可靠揭示伽马射线辐射的起源并开展统计研究,人们需要更大的样本。基于这一考虑,2014年以来我们系统的进行了伽马射线球状星团的搜寻并取得显著进展。2014年底我们分析了Fermi-LAT的Pass 7Rep的数据,证实球状星团2MS-GC01和IC 1257是伽马射线源,在球状星团NGC 5904、NGC 6656和FSR 1735的潮汐半径内发现了伽马射线辐射存在的证据或迹象(见第2章)。2015年6月底,Fermi-LAT组公开了Pass8的数据,该数据与之前的版本相比对伽马射线的能量分辨、角度分辨、有效探测面积等方面都有了显著提高,这些提高对于寻找低纬度的暗弱源甚为关键。因此我们采用了近7年的Pass8数据来寻找新的伽马射线球状星团(见第3章)。我们的数据分析证实了球状星团NGC 5904的伽马射线辐射,并发现了球状星团M 15和NGC 6397的伽马射线辐射,其中NGC 6397是距离最近的伽马射线球状星团。我们用球状星团伽马射线的光度估计了球状星团中的脉冲星的总数量。数据分析中没有发现这些球状星团的伽马射线流量存在明显的变化,也没发现它们的脉冲辐射。这表明所探测到的伽马射线来自于一组而不是单个脉冲星的曲率辐射或者是脉冲星高能电子对星风对低能光子的逆康普顿散射。我们也处理分析了2014期间双星系统PSRB1259-63/LS2883在过近星点时的伽马射线和X射线波段的数据。它的伽马射线波段的流量在近星点后33天有一个很强的伽马射线耀发。其流量强度大于它宁静态下流量的10倍。它的光变曲线在天量级甚至小于天量级的尺度上都有明显的光变。伽马射线和X射线的变化特征和2010/2011年此源的经过近星点时的辐射特征几乎一样(见第4章)。在第5章我们对球状星团的研究成果进行了小结并对利用我国暗物质粒子探测卫星数据来开展这方面的工作的前景予以了展望。
[Abstract]:The globular cluster is a globular self-gravitational binding system consisting of a large number of low-metal-rich aged stars (characteristic age 10 billion years). To date, 158 globular clusters have been discovered in the Milky way. After the successful launch of the .Fermi satellite, which detected only optical and radio radiation from such sources before 2008, the gamma-ray radiation of the globular clusters was successfully detected. It is further recognized as a new type of gamma radiation source. Due to the low latitudes of most globular clusters, it is difficult to authenticate due to the obvious effect of the diffuse background gamma ray radiation on the silver disk. To date, the number of gamma-ray globular clusters is extremely limited. In order to reliably reveal the origin of gamma radiation and carry out statistical research, larger samples are needed. Based on this consideration, we have systematically searched gamma-ray globular clusters since 2014 and made significant progress. At the end of 2014, we analyzed Fermi-LAT 's Pass 7Rep data and confirmed that globular cluster 2MS-GC01 and IC 1257 are gamma ray sources. Evidence or signs of the presence of gamma radiation have been found in the tidal radii of the globular cluster NGC 5904 / NGC 6656 and FSR 1735 (see chap. 2). The Fermi-LAT group released Pass8 data at the end of June 2015, which compares with previous versions of the energy resolution of gamma rays. Angle resolution and effective detection area have been greatly improved, which is crucial for finding dark weak sources at low latitudes. So we have used the Pass8 data of nearly 7 years to find new gamma-ray globular clusters (see Chapter 3). Our data analysis confirms the gamma-ray radiation of globular cluster NGC 5904, and the gamma-ray radiation of globular cluster M15 and NGC 6397, in which NGC 6397 is the nearest gamma-ray globular cluster. We estimate the total number of pulsars in globular clusters by the luminosity of gamma rays of globular clusters. There is no obvious change in the gamma ray flux of these globular clusters or their pulse radiation in the data analysis. This indicates that the detected gamma rays are derived from the curvature radiation of a group of pulsars, not from a single pulsar, or from the inverse Compton scattering of low-energy photons by high-energy electrons from pulsars. We have also processed and analyzed the gamma ray and X ray band data of the binary system PSRB1259-63/LS2883 over the near star during 2014. Its gamma-ray band has a strong gamma-ray flare 33 days after the star. The flow intensity is 10 times greater than that under static condition. Its light change curve has obvious light variation on the scale of sky order or even less than sky magnitude. The variation characteristics of gamma rays and X-rays are almost the same as those of the sources passing near the stars in 2010 / 2011 (see chap. 4). In Chapter 5, we summarize the research results of globular clusters and give a prospect of using our country's dark matter particle detection satellite data to carry out this work.
【学位授予单位】：云南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P154.12

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