本文關鍵詞： 星系消光 星系質量 恒星形成率　出處：《南京大學》2015年碩士論文　論文類型：學位論文

【摘要】：我們基于簡單星族合成模型(Bruzual Charlot 2003；BC03)結合星系的恒星形成歷史,金屬豐度,塵埃消光以及速度彌散建立了模型星系庫。我們利用主成分分析法(Principle component analysis;PCA)對這些模型庫星系3700到5500埃范圍內的光譜提取本征譜。這些本征譜的線性組合即是我們得到的觀測星系擬合光譜。這些擬合光譜涵蓋了星系觀測光譜中D4000,HδA等信息。此外,我們基于這種方法來估算星系的物理參數(shù),包括：比恒星形成率(SFR/M*),z波段質光比(M*/Lz)和V波段光深(τV)等。并把估算得到的參數(shù)值與其輸入值進行比較,以此來研究影響星系基本物理參數(shù)估算的兩個因素。第一,模型星系庫輸入?yún)?shù)的先驗分布對估算星系基本物理參數(shù)的影響。我們對輸入?yún)?shù)之一τV采用兩種不同先驗分布來建立模型星系庫,分別對模擬星系參數(shù)進行估算,發(fā)現(xiàn)通常利用星云發(fā)射線得到的臨近星系τV值的分布會使計算得到的τV值在星系塵埃消光較低或較高時偏離真實分布。第二,觀測星系光譜信噪比(SNR)對估算星系基本物理參數(shù)的影響。通過對添加不同程度噪聲的模擬星系基本物理參數(shù)的估算,我們得到了SFR/M*、M*/Lz和τV這些參數(shù)的估算精度隨信噪比的變化關系。最后,我們計算了在SDSS DR7中選擇的5000個恒星形成星系的τV值,并和之前由星云發(fā)射線得到的τV值進行比較。我們發(fā)現(xiàn)由連續(xù)譜和吸收線得到的τV比由星云發(fā)射線得到的τV系統(tǒng)地小大約0.5dex,我們認為由星云發(fā)射線得到的τV反映了恒星形成區(qū)的τV,而由連續(xù)譜和吸收線得到的τV更多是恒星形成區(qū)以外恒星際介質產生的。由于恒星形成區(qū)的氣體塵埃豐富,因此具有更高的消光值。我們得到的這一結果也進一步驗證了Charlot Fall(2000)的雙參數(shù)塵埃消光模型。
[Abstract]:We based on the simple star family synthesis model Bruzual Charlot 2003; BC03) combines the galaxy's stellar formation history, metal abundance. The model galactic library is established by dust extinction and velocity dispersion. We use principal component analysis (PCA) to analyze the model galaxies. PCA). The intrinsic spectra are extracted from the spectra of these model base galaxies in the range of 3700 to 5500 A. the linear combination of these spectra is the fitting spectra of the observed galaxies. These fitting spectra cover the observed light of the galaxies. D4000 in the spectrum. In addition, we use this method to estimate the physical parameters of galaxies, including: higher star formation rate (SFR / MN). The z band mass / light ratio (MZ) and the V band light depth (蟿 V) are compared with the input values. Two factors affecting the estimation of the basic physical parameters of galaxies are studied. The influence of the prior distribution of input parameters on the estimation of the basic physical parameters of galaxies is discussed. Two different prior distributions are used to establish the model galactic library for 蟿 V, one of the input parameters. The parameters of simulated galaxies are estimated respectively. It is found that the distributions of 蟿 V values usually obtained from nebula emission lines will cause the calculated 蟿 V values to deviate from the true distribution when the extinction of galaxy dust is low or high. The influence of SNR on the estimation of the basic physical parameters of galaxies is observed. By estimating the basic physical parameters of simulated galaxies with different noise levels, we obtain SFR / M *. The estimation accuracy of the parameters M / L z and 蟿 V varies with the SNR. Finally, we calculate the 蟿 V values of 5 000 star forming galaxies selected in SDSS DR7. Compared with the previous 蟿 V values obtained from the nebula emission line, we find that 蟿 V obtained from the continuous spectrum and the absorption line is about 0.5dex smaller than the 蟿 V value obtained from the nebula emission line. We believe that 蟿 V from the emission line of the nebula reflects 蟿 V in the star forming region. The 蟿 V obtained from the continuous spectrum and absorption line is more produced by the constant interstellar media outside the star forming region, because the gas dust in the star formation region is abundant. Therefore, a higher extinction value is obtained, which further verifies the two-parameter dust extinction model of Charlot Fallt2000).
【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P152

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