Formation and Evolution of Elliptical Galaxies and Globular Cluster Systems

我们通过分析椭圆星系内部和周围恒星群的性质、热x射线气体以及星系周围球状星团系统的特征，研究了椭圆星系的形成和演化。首先，我们建立了一个新的化学和光谱演化模型，适用于任何恒星形成历史的星系。2将该模型应用于室女星团中椭圆星系周围球状星团的光度和颜色函数，发现这些星团形成于12-18 Gyrs之前的2-3 Gyrs。2接下来，我们编制了射电选择椭圆星系的光谱能量分布数据，发现z >= 2的星系显示出明显的大尺度恒星形成的证据，而更近的星系则没有。我们取得了28个螺旋星系凸起的光谱，令人信服地表明凸起的光度-金属丰度关系与椭圆星系的相同。在宇宙演化的早期，更多的弛豫以原星系坍缩和耗散恒星形成为主。5 .椭圆星系周围热x射线气体的铁丰度应该至少等于甚至超过椭圆星系的平均铁丰度，但我们利用ASCA x射线卫星获得的铁丰度要低得多。通过对天体物理学知识的详细调查，我们得出结论，用于数据还原的等离子体代码中铁l线的基本原子物理数据一定有问题。我们仔细地重新估计了星系团内介质中元素的相对丰度比，通过正确地使用太阳陨石铁丰度，发现ICM中铁的来源应该主要是Ia型超新星，而不是II型，这与最近文献中的说法相反。5-6从化学进化的角度支持了2-4的结论。最后，我们认为直接探测恒星形成时期的椭圆星系是最重要的，这在CO光度峰中可以得到最好的探测。为了将CO光度的演化纳入我们的模型，我们研究了盘状星系中CO和HI气体的空间分布，并获得了CO到H2分子的转换因子，该转换因子与气体金属丰度成反比。这一新知识可以应用于我们下一步通过CO射电观测寻找恒星形成的椭圆。少

We have studied the formation and evolution of elliptical galaxies by analysing the nature of stellar populations and the hot X-ray gas in and around elliptical galaxies as well as the characteristics of globular cluster systems around galaxies. 1 First, we have built a new chemical and spectral evolution model for galaxies of any star formation history. 2 By appling this model to the luminosity and color function of globular clusters around elliptical galaxies in Virgo cluster, we find that these cluster formed about 12-18 Gyrs ago in 2-3 Gyrs. 2 Next, we have compiled the spectral energy distribution data of radio-selected elliptical galaxies, and find that galaxies at z >= 2 show a conspicuous evidence for large scale star formation, while those nearer do not. 4 We have taken spectra of 28 bulges of spiral galaxies and convincingly show that the luminosity-metallicity relation of bulges is identical to that of elliptical galaxies. 2-4 strongly suggest that formation of elliptical ga … More laxies was dominated by protogalactic collapse and dissipational star formation early in the evolution of the universe. 5 The iron abundance of the hot X-ray gas around elliptical galaxies should be at least equal to or even more than the mean stellar iron abundance of ellipticals, and yet we have obtained much lower iron abundances by using ASCA X-ray satelite. Through a detailed investigation based on our knowledges on astrophysics, we reach to a conclusion that there must be something wrong in the fundamental atomic physics data of iron L-lines in the plasma code used for data reduction. 6 We have carefully re-estimated the relative abundance ratios of elements in the intracluster medium, by correctly using the solar meteoritic iron abundance, and find that the origin of iron in the ICM should be mainly in type Ia supernovae and not in type II,contrary to the recent claims in the literature. 5-6 give another support from chemical evolution approach to the conclusion reached by 2-4. Finally, we believe it is of prime importance to detect directly elliptical galaxies at star formation epoch, which could be best detected in CO luminosity peak. 7 To involve the evolution of CO luminosity in our model, we study the spatial distribution of CO and HI gas in disk galaxies and obtain the conversion factor from CO to H2 molecules that is inversely proportinal to the gas metallicity. This new knowledge could be applied to our next step for a search of star forming ellipticals by CO radio observation. Less