Galaxy Astronomy by Sloan Digital Sky Survey

SDSS项目整体上没有重大问题，预计调查将于2005年完成。我们在2003年春季完成了第一次重大公开数据发布(DR1)。DR1将15%的调查提供给世界各地的天文研究人员以及普通公众。2003年春，我们已经完成了60%的成像和40%的光谱分析。我们发现了z=6.4的类星体，这是迄今为止已知的最远的类星体。它在短波区的吸收特征表明，z=6.0是宇宙由非电离向电离转变的时期。这一观测证据首次被报道。我们继续发现引力透镜类星体(GL-类星体)。到目前为止，它们都是本课题组利用SDSS数据发现的。GL-类星体的数量比理论预测的要少一些。这是一个非常有趣的问题，需要尽快研究。我们还开始寻找分离较大的GL-类星体，并且已经找到了几个很好的候选星系。我们确认了有两种特殊的星系，1)没有恒星形成的螺旋星系(我们称之为“被动螺旋”)和2)有恒星形成的椭圆星系(E+A星系)。我们的分析表明，被动螺旋星系停止形成恒星是因为它们的气体和尘埃被剥离，后来它们合并成了正常的椭圆星系。另一方面，我们认为E+A星系与星系团是孤立的，对星系团的演化没有贡献。

SDSS Project, as a whole, did not have ant major problems, foreseeing the completion of the survey in 2005. We have accomplished the first major public data release (DR1) in the spring of 2003. DR1 makes 15% of the total survey available to all astronomical researchers world wide as well as general public. In the spring of 2003, 60% of imaging and 40% of spectroscopy have completed.We have found z=6.4 QSO, the most distant QSO known to the date. Its absorption feature in short wavelength region suggests that z=6.0 is the era when the universe changed from non-ionized to ionized. This observational evidence was first reported by this observation.We continue to find gravitationally lensed QSOs (GL-QSOs). So far, all of them are found by our group using SDSS data. The number of GL-QSO is a few factor smaller than theoretical prediction. This is a very interesting problem need to be studied soon. We also stared to search GL-QSOs that have a large separation and already found several good candidates.We confirmed that there are two special kinds of galaxies, 1) spiral galaxies without star formation (we named them "passive spiral"), and 2) elliptical galaxies with star formation (E+A galaxies). Our analysis suggests that the passive spiral galaxies stopped forming stars because their gas and dust were stripped and that they later on merged into normal elliptical galaxies. On the other hand, we think, E+A galaxies are isolated from clusters and do not contribute to the cluster evolution.