Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK.
Nature. 2011 Jun 29;474(7353):616-9. doi: 10.1038/nature10159.
The intergalactic medium was not completely reionized until approximately a billion years after the Big Bang, as revealed by observations of quasars with redshifts of less than 6.5. It has been difficult to probe to higher redshifts, however, because quasars have historically been identified in optical surveys, which are insensitive to sources at redshifts exceeding 6.5. Here we report observations of a quasar (ULAS J112001.48+064124.3) at a redshift of 7.085, which is 0.77 billion years after the Big Bang. ULAS J1120+0641 has a luminosity of 6.3 × 10(13)L(⊙) and hosts a black hole with a mass of 2 × 10(9)M(⊙) (where L(⊙) and M(⊙) are the luminosity and mass of the Sun). The measured radius of the ionized near zone around ULAS J1120+0641 is 1.9 megaparsecs, a factor of three smaller than is typical for quasars at redshifts between 6.0 and 6.4. The near-zone transmission profile is consistent with a Lyα damping wing, suggesting that the neutral fraction of the intergalactic medium in front of ULAS J1120+0641 exceeded 0.1.
星系际介质直到大爆炸后约 10 亿年才完全重新电离，这一点可以通过观测红移小于 6.5 的类星体得到证实。然而，由于类星体历史上是在光学调查中被发现的，而光学调查对红移超过 6.5 的源不敏感，因此很难探测到更高的红移。在这里，我们报告了对一个红移为 7.085 的类星体（ULAS J112001.48+064124.3）的观测结果，它是大爆炸后 0.77 亿年的时期。ULAS J1120+0641 的光度为 6.3×10(13)L(⊙)，拥有一个质量为 2×10(9)M(⊙)的黑洞（其中 L(⊙)和 M(⊙)分别是太阳的光度和质量）。测量到的 ULAS J1120+0641 周围电离近区的半径为 1.9 兆秒差距，比红移在 6.0 到 6.4 之间的类星体通常要小三倍。近区传输轮廓与 Lyα 阻尼翼一致，表明 ULAS J1120+0641 前方星系际介质的中性分数超过 0.1。
