Wyithe J Stuart B, Loeb Abraham
Astronomy Department, Harvard University, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
Nature. 2002 Jun 27;417(6892):923-5. doi: 10.1038/nature00794.
Exceptionally bright quasars with redshifts up to z = 6.28 have recently been discovered. Quasars are thought to be powered by the accretion of gas onto supermassive black holes at the centres of galaxies. Their maximum (Eddington) luminosity depends on the mass of the black hole, and the brighter quasars are inferred to have black holes with masses of more than a few billion solar masses. The existence of such massive black holes poses a challenge to models for the formation of structures in the early Universe, as it requires their formation within one billion years of the Big Bang. Here we show that up to one-third of known quasars with z approximately equal to 6 will have had their observed flux magnified by a factor of ten or more, as a consequence of gravitational lensing by galaxies along the line of sight. The inferred abundance of quasar host galaxies, as well as the luminosity density provided by the quasars, has therefore been substantially overestimated.
最近发现了红移高达z = 6.28的异常明亮的类星体。人们认为类星体是由气体吸积到星系中心的超大质量黑洞上提供能量的。它们的最大（爱丁顿）光度取决于黑洞的质量，据推断，较亮的类星体拥有质量超过数十亿个太阳质量的黑洞。如此巨大的黑洞的存在对早期宇宙中结构形成的模型提出了挑战，因为这需要它们在大爆炸后的十亿年内形成。我们在此表明，由于视线方向上星系的引力透镜效应，高达三分之一的已知红移约为6的类星体其观测到的流量会放大十倍或更多。因此，推断出的类星体宿主星系的丰度以及类星体提供的光度密度都被大幅高估了。
