标题： 一个QSO宿主星系及其在z=6.43时的Lyα发射 显示英文标题

标题： A QSO host galaxy and its Lyalpha emission at z=6.43

摘要： 我们报告了在 z=6.43（CFHQSJ2329-0301，目前所知最遥远的类星体）周围扩展结构的光学探测结果，这些探测基于斯巴鲁/超广角相机在深 z' 和 z_r 波段图像中的数据。 经过仔细的点扩散函数（PSF，针对类星体）减除处理后，在 z' 波段中，该结构在天空上延伸超过 4'' （R_e=11 kpc），因此得到了很好的分辨（16σ 检测）。减去 PSF 后的 z_r 波段结构形状与 z' 波段相似，但显著性较低（3σ 检测）。在 z' 波段中，类星体加宿主星系的径向分布显示出在 0.8-3'' 半径范围内明显高于平均 PSF 的超额。 由于 z' 波段包含了 z=6.43 处的 Lyα 发射线，z' 流量可能是宿主（连续光）和其 Lyα 发射线的混合物，而 z_r 波段的流量则来自宿主。通过谱能量分布建模，我们估计 PSF 减除后的 z' 波段光中有 40% 来自宿主（连续光），60% 来自 Lyα 发射线。宿主的绝对星等为 M_{1450}=-23.9 （与之相比，M_{1450}=-26.4 对于类星体）。假设年龄为 100 百万年时，Lyα 发射对应的恒星形成率（SFR）下限为 1.6 Msun yr^{-1}，恒星质量范围为 6.2 x 10^8 至 1.1 x 10^10 Msun。 这一发现表明，在宇宙早期大爆炸后约 8.4 亿年，一个明亮的类星体已经存在于一个大型的恒星形成星系中。宿主可能是正在形成的巨型星系，与超大质量黑洞共同演化。 显示英文摘要

摘要： We report an optical detection of an extended structure around a QSO at z=6.43 (CFHQSJ2329-0301, the highest redshift QSO currently known) in deep z' and z_r-band images of the Subaru/Suprime-Cam. After a careful PSF (QSO) subtraction, a structure in the z'-band extends more than 4'' on the sky (R_e=11 kpc), and thus, is well-resolved (16sigma detection). The PSF-subtracted z_r-band structure is in a similar shape to that in the z'-band, but less significant with a 3 sigma detection. In the z'-band, a radial profile of the QSO+host shows a clear excess over that of the averaged PSF in 0.8-3'' radius. Since the z'-band includes a Lya emission at z=6.43, the z' flux is perhaps a mixture of the host (continuum light) and its Lya emission, whereas the z_r-band flux is from the host. Through a SED modeling, we estimate 40% of the PSF-subtracted z'-band light is from the host (continuum) and 60% is from Lya emission. The absolute magnitude of the host is M_{1450}=-23.9 (c.f. M_{1450}=-26.4 for the QSO). A lower limit of the SFR(Lya) is 1.6 Msun yr^{-1} with stellar mass ranging 6.2 x 10^8 to 1.1 x 10^10 Msun when 100 Myrs of age is assumed. The detection shows that a luminous QSO is already harbored by a large, star-forming galaxy in the early Universe only after ~840 Myr after the big bang. The host may be a forming giant galaxy, co-evolving with a super massive black hole.