Observational Studies of High Redshift Quasars

将通过对高红移类星体进行系统的观测来研究类星体的红移截止。众所周知，具有特定光度的类星体的数量随着红移的增加而增加。然而，除了2.5或3的红移之外，类星体的数量也有所下降。这一现象可能标志着宇宙中类星体的首次出现，也就是大爆炸后大约20亿年。目前，高红移时类星体数量的下降还没有得到很好的记录。这些类星体非常罕见。通常情况下，在天空中的10,000颗恒星中会发现一个高红移类星体。这项测量技术将包括用位于帕洛马的200英寸望远镜对大约100万个微弱物体的低色散光谱进行视频记录。将选择显示发射线的对象。所有发射线天体的后续光谱将显示这些天体中的哪些是类星体，并测量它们的红移。通过对调查的仔细控制和校准，将有可能评估其完整性限度，从而对高红移类星体进行定量普查。这些结果将允许评估不同的假说，这些假说被用来解释类星体在早期宇宙中突然出现的原因。这一现象很可能与星系的诞生有关。

The redshift cutoff of quasars will be studied by carrying out systematic surveys for high-redshift quasars. It is known that the number of quasars of given luminosity increases with increasing redshift. Beyond a redshift of 2.5 or 3, however, there is a drop in quasar numbers. This phenomenon probably signifies the first appearance of quasars in the universe, about 2 billion years after the Big Bang. At the present time the drop in quasar numbers at high redshift is poorly documented. These quasars are very rare. Typically one high-redshift quasar is found among 10,000 stars in the sky. The survey technique will involve video recording the low-dispersion spectra of approximately 1 million faint objects with the 200-inch telescope at Palomar. The objects that show emission lines will be selected. Follow-up spectroscopy of all the emission-line objects will show which of these objects are quasars as well as measure their redshifts. By careful control and calibration of the survey, it will be possible to evaluate its completeness limits, and thus conduct a quantitative census of high-redshift quasars. The results will allow the evaluation of different hypotheses proposed to explain the sudden appearance of quasars in the early universe. This phenomenon may well be associated with the birth of galaxies.