本文選題：引力透鏡-射電噴流-星系-宇宙弦 + 大尺度結(jié)構(gòu)　； 參考：《南京大學(xué)》2011年碩士論文

【摘要】：弱引力透鏡作為研究宇宙學(xué)的一種觀測手段已經(jīng)發(fā)展得相當(dāng)成熟,并且已經(jīng)被用于探測暗物質(zhì)、暗能量以及宇宙大尺度結(jié)構(gòu)的相關(guān)參數(shù)。這種效應(yīng)因其只與透鏡天體的引力場有關(guān),因而比較適合用于探測宇宙弦等具有特殊引力效應(yīng)的物質(zhì)。 許多理論都預(yù)言了宇宙弦的存在,并給出了理論的預(yù)期。在觀測上,微波背景輻射,大尺度結(jié)構(gòu),引力波探測已經(jīng)對宇宙弦的參數(shù)給出了一定限制。而且微引力乃至強(qiáng)引力透鏡技術(shù)也被用于某些背景天體來探測宇宙弦,但至今仍無法證實宇宙弦的存在。而弱引力透鏡技術(shù)將給宇宙弦的探測開辟一個新的窗口。 本文研究了宇宙弦的弱引力透鏡效應(yīng)并給出了一些探測宇宙弦的方法。Konberg教授首次提出用射電噴流的引力扭曲作為探測透鏡天體的技術(shù),并且用“準(zhǔn)線破缺因子”作為透鏡效應(yīng)的特征參量。我們把這種特征參量用于探測無限長扭曲弦的引力形變。然后,透過研究噴流的非常數(shù)偏轉(zhuǎn)角,我們發(fā)現(xiàn)“準(zhǔn)線破缺因子”與噴流的斜率有關(guān)。如果宇宙弦存在的話,在“平方公里陣列”(SKA)的樣本中大概有3個噴流具有明顯的觀測信號(ηGG10°)。 我們也研究了橢球天體的引力形變并且運用數(shù)值方法進(jìn)一步研究了星系的軸向角分布和橢率分布。我們發(fā)現(xiàn)當(dāng)背景星系的方向與宇宙弦的方向平行的時候,我們就得到了一個與橢率分布模型無關(guān)的形如“v”的軸向角分布。而且研究發(fā)現(xiàn)這些具有特殊位置的樣本星系在宇宙弦作用下會變得更圓,使得它們的橢率分布發(fā)生顯著變化。通過數(shù)值統(tǒng)計比較兩種統(tǒng)計量的信噪比,我們發(fā)現(xiàn)橢率的分布變化較軸向的分布變化更為明顯。橢率的分布變化可以在現(xiàn)有的巡天樣本如斯隆數(shù)字巡天(SDSS)中得以檢驗,而軸向分布變化的檢驗有待于將來更大的巡天數(shù)據(jù)的公布,比如Large Synoptic Survey Telescope (LSST)和Dark Energy Survey (DES)。這些巨大的巡天樣本可以對宇宙弦的分布和性質(zhì)給出更強(qiáng)限制。
[Abstract]:Weak gravitational lensing as a cosmological observation method has been developed quite mature and has been used to detect dark matter dark energy and the relevant parameters of cosmic large-scale structure. Because this effect is only related to the gravitational field of a lens object, it is more suitable for detecting materials with special gravitational effects such as cosmic strings. Many theories predict the existence of cosmic strings and give theoretical expectations. In observation, microwave background radiation, large scale structure and gravitational wave detection have limited the parameters of cosmic string. Microgravity and even strong gravitational lensing are also used to detect cosmic strings in some background objects, but the existence of cosmic strings has not yet been confirmed. The weak gravitational lensing technology will open a new window for the detection of cosmic strings. In this paper, the weak gravitational lensing effect of cosmic strings is studied and some methods for detecting cosmic strings are given. Professor Konberg proposed for the first time that the gravitational distortion of radio jet current can be used as the technique of detecting lensed celestial bodies. In addition, the "criterion breaking factor" is used as the characteristic parameter of the lens effect. We use this characteristic parameter to detect the gravitational deformation of infinitely long twisted strings. Then, by studying the non-constant skew angle of the jet, we find that the "criterion breaking factor" is related to the slope of the jet. If the cosmic strings exist, about three of the samples of the "square kilometer array" SKA have obvious observational signals (畏 GG10 擄). We also study the gravitational deformation of ellipsoidal bodies and further study the axial angular distribution and ellipticity distribution of galaxies by numerical method. We find that when the direction of the background galaxy is parallel to the direction of the cosmic string, we obtain an axial angular distribution such as "v" which is independent of the ellipticity distribution model. Moreover, it is found that these sample galaxies with special positions become more circular under the action of cosmic strings, resulting in a significant change in their ellipticity distribution. By comparing the signal-to-noise ratio of the two statistics, we find that the variation of ellipticity distribution is more obvious than that of axial distribution. The variation of ellipticity distribution can be tested in the existing aerial survey samples such as Sloan Digital aerial Survey (SDSS), while the axial distribution change is to be verified by the publication of larger survey data in the future, such as Large Synoptic Survey Telescope / LSST) and Dark Energy Survey / DSS. These large aerial surveys can impose greater restrictions on the distribution and properties of cosmic strings.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2011
【分類號】：P111

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相關(guān)期刊論文 前2條

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本文編號：1843809