Luminous quasars that harbor superm

Luminous quasars that harbor supermassive black holes (SMBHs) are now identified out to as early as the age of the Universe less than 1 Gyr. The existence of such SMBHs is intriguing since growing SMBHs under the standard Eddington-limited accretion is difficult within the short period constrained by the age of the universe at z = 6. Thus, the expectation is such that the most massive SMBHs at 10^10 Msun must be in the process of its intense growth at z ~ 6. Here, we provide an observational evidence that the most massive SMBHs are just emerging at z ~ 6 for the first time, using the rest-frame optical spectra taken with IRC on the AKARI infrared space telescope at the obervational window of 2.5 - 5.0 micron. With the AKARI IRC spectroscopy, we succeeded in detecting the redshifted H-alpha line for the first time which provides a reliable measure of SMBH mass for quasars at 3 < z < 6.42. The number density of SMBHs with 10^10 Msun quickly drops at z > 6, while the Eddington ratio of those high redshift QSOs are near at unity, suggesting that the most massive SMBHs are in the process of rapid growth, but has not reached 10^10 Msun. We will also discuss implication of our results for the search of quasars at z > 6, and briefly overview our current survey of high redshift quasars.

Results (English) 2:

明亮的类星体，港超大质量的黑洞（SMBHs）已经确定了早期宇宙的年龄小于1 GYR。这样的超大质量黑洞存在的是有趣的因为越来越多的超大质量黑洞吸积在标准的爱丁顿有限公司很难在短时间内受到宇宙的年龄在z = 6。因此，期望是这样的，在10
10 Msun最庞大的超大质量黑洞必须在Z ~ 6在其强烈的生长过程。在这里，我们提供了观测证据最庞大的SMBHs刚刚出现在Z ~ 6的第一时间，使用其余帧的光的光谱在2.5 - 5微米的obervational窗口上的“红外太空望远镜的IRC。与明IRC光谱，我们成功地在红移的H-线的第一时间提供了可靠的SMBH质量测量类星体在3≤z≤6.42检测。10
10 Msun迅速下降，在Z＞6的超大质量黑洞的数密度，而那些高红移类星体的爱丁顿比率接近一致，表明大质量黑洞正在快速成长的过程中，但还不到10
10 Msun。我们还将讨论我们在Z＞6类星体的搜索结果的意义，并简要概述我们的高红移类星体的现状调查。