Evolutionary Transition of Galaxies

星系的演化转变

基本信息

批准号：
09640311
负责人：
ARIMOTO Nobuo
金额：
$ 2.3万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

An evolutionary transition of galaxies is defined as a sudden decline of star forming activity in young galaxies. We have built up an evolutionary model of galaxy spectra and have applied it to elliptical galaxies in clusters. We find that color-magnitude (CM) relation of elipticals is due to a systematic variation of mean stellar metallicity as a function of galaxy luminosity which could be best explained by a galactic wind model. We find that evolution of the CM relation strongly depends on an epoch of major star formation. A detailed comparison of our model CM relation with those of elliptical galaxies in clusters at different redshifts strongly suggests that these galaxies should have formed at zィイD2FィエD2 > 2.5 - 4.We measured equibalent widths of several metallic lines in high redshift (z 〜 3 - 4) quasars and found very strong iron emission there. This suggests that at least interstellar matter of host galaxies of these quasars was already enriched by ejecta of type Ia supernovae. … More Thus, galaxies at these redshifts are older than SNIa progenitors, a typical lifetime of which is around 1.5 Gyr. This means the host galaxies of these quasars, very likely elliptical galaxies, formed at zィイD2FィエD2 > 5 - 9.Simple calculation of CO luminosity of cluster ellipticals, based on our CM relation analysis, indicates that CO luminosity during actively star forming phase must be high enough to be detected by radio telescope. This reasonablly explains why we can detect CO in a quasar at z = 4.6, if the host galaxy is an elliptical before the onset of evolutionary transition.From these results, we conclude that the evolutionary transition in elliptical galaxies occurred at z 〜 4 - 5, possibly due to a galactic wind.With a hope that in near future submillimeter observations will become more easier and we will be able to get more spectra of galaxies in these wavelength region, we have newly built up an evolutionary model of galaxy spectra in which effects of dust absorption and re-emission are fully taken into account. We have applied the model to nearby star burst galaxies and are successful in desentagling age and dutiness from the observed optical-nearinfrared and farinfrared colours. Since primeval galaxies at high redshifts would be very similar to those nearby starburst galaxies, we believe that we have established a way to derive the age of these high redshift galaxies without any uncertainties. This would eventually lead us to estimate the epoch of formation of these primival galaxies. Less

星系的进化过渡被定义为年轻星系中恒星形成活性的突然下降。我们已经建立了一个星系光谱的进化模型，并将其应用于簇中的椭圆星系。我们发现，Elipticals的颜色障碍（CM）关系是由于平均恒星金属性的系统变化是星系光度的函数，这可以通过银河风模型来最好地解释。我们发现CM关系的演变很大程度上取决于主要恒星形成的时期。我们的模型CM关系与不同红移簇中的椭圆星系的详细比较表明，这些星系应该在ZII D2FIE D2> 2.5-2.5-4中形成。4。我们测量了高红移（Z〜3-4 4）Quasars（Z〜3-4）的数量（Z〜3-4）Quasars和非常强的Irions Sissions的几种金属线的同等宽度。这表明，这些类星体的宿主星系中至少星际问题……更多的是，这些红移的星系比SNIA祖细胞更古老，SNIA祖细胞的典型寿命约为1.5 gyr。这意味着根据我们的CM关系分析，在ZII D2FIE D2> 5-9中形成的这些类星体的宿主星系，非常可能的椭圆星系，在ZII D2FIE D2> 5-9.集群椭圆形的CO亮度计算中，这表明在星形阶段期间的CO亮度必须足够高，必须足够高以在无线电望远镜的范围内检测到足够高。这个合理地解释了为什么我们可以在z = 4.6中检测到CO，如果主机星系在进化过渡开始之前是椭圆形，从这些结果中包括，我们包括在Z〜4-5发生的椭圆形星系中的进化过渡，这可能是由于近来的构建模型而变得更加近代的构建模型。在这些波长区域中的星系，我们新建立了一个星系光谱的进化模型，其中充分考虑了粉尘吸收和重新排放的影响。我们已经将模型应用于近恒星爆发星系，并从观察到的光学北非和法林河颜色中成功地发出了年龄和责任。由于高红移的原始星系与近乎星际星系非常相似，因此我们相信我们已经建立了一种方法来推导这些高红移星系的年龄而没有任何不确定性。这最终将导致我们估计这些主要星系的形成时代。较少的