近日，日本东京大学的Xuheng Ding&Masafusa Onoue及其研究小组取得一项新进展。经过不懈努力，他们成功探测到红移6以上的类星体宿主星系中的恒星光谱。相关研究成果已于2023年6月28日在国际权威学术期刊《自然》上发表。

该研究小组报道了利用詹姆斯·韦伯太空望远镜（JWST）探测到的两个HSC-SSP类星体在z>6红移处的静态光学图像和光谱。研究人员利用NIRCam在3.6μm和1.5μm波长进行成像，并从未解析的类星体光谱中减去背景信号。结果发现，这些类星体的宿主星系具有巨大的质量（恒星质量分别为13×10¹⁰ M_⊙和3.4×10¹⁰ M_⊙），且呈现出致密的类盘状结构。通过NIRSpec的高分辨率光谱观测，研究人员成功探测到了更大质量类星体宿主星系中的恒星吸收线，进一步证实了宿主星系的存在。

同时，他们还通过测量类星体附近速度展宽的气体，推断出它们的黑洞质量（分别为1.4×10⁹和2.0×10⁸ M_⊙）。这些类星体在黑洞质量-恒星质量平面上的位置与低红移的类星体分布一致，这表明黑洞与宿主星系之间的关系在大爆炸之后的不到10亿年内已经形成。

据悉，在再电离时期（z>6），类星体宿主星系发出的星光一直难以捕捉，即使通过深度的HST观测也如此。目前探测到的最高红移类星体宿主位于z=4.5处，需要依靠前景透镜星系的放大效应才能探测到。然而，来自超主焦点相机昴星团望远镜战略计划（HSC-SSP）的低亮度类星体使得探测潜在、以前未被发现的宿主星系的挑战得到缓解。

附：英文原文

Title: Detection of stellar light from quasar host galaxies at redshifts above 6

Author: Ding, Xuheng, Onoue, Masafusa, Silverman, John D., Matsuoka, Yoshiki, Izumi, Takuma, Strauss, Michael A., Jahnke, Knud, Phillips, Camryn L., Li, Junyao, Volonteri, Marta, Haiman, Zoltan, Andika, Irham Taufik, Aoki, Kentaro, Baba, Shunsuke, Bieri, Rebekka, Bosman, Sarah E. I., Bottrell, Connor, Eilers, Anna-Christina, Fujimoto, Seiji, Habouzit, Melanie, Imanishi, Masatoshi, Inayoshi, Kohei, Iwasawa, Kazushi, Kashikawa, Nobunari, Kawaguchi, Toshihiro, Kohno, Kotaro, Lee, Chien-Hsiu, Lupi, Alessandro, Lyu, Jianwei, Nagao, Tohru, Overzier, Roderik, Schindler, Jan-Torge, Schramm, Malte, Shimasaku, Kazuhiro, Toba, Yoshiki, Trakhtenbrot, Benny, Trebitsch, Maxime, Treu, Tommaso, Umehata, Hideki, Venemans, Bram P., Vestergaard, Marianne, Walter, Fabian, Wang, Feige, Yang, Jinyi

Issue&Volume: 2023-06-28

Abstract: The detection of starlight from the host galaxies of quasars during the reionization epoch (z>6) has been elusive, even with deep HST observations. The current highest redshift quasar host detected, at z=4.5, required the magnifying effect of a foreground lensing galaxy. Low-luminosity quasars from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) mitigate the challenge of detecting their underlying, previously-undetected host galaxies. Here we report rest-frame optical images and spectroscopy of two HSC-SSP quasars at z>6 with JWST. Using NIRCam imaging at 3.6μm and 1.5μm and subtracting the light from the unresolved quasars, we find that the host galaxies are massive (stellar masses of 13×and 3.4×10¹⁰ M_⊙, respectively), compact, and disk-like. NIRSpec medium-resolution spectroscopy shows stellar absorption lines in the more massive quasar, confirming the detection of the host. Velocity-broadened gas in the vicinity of these quasars enables measurements of their black hole masses (1.4×10⁹ and 2.0×10⁸ M_⊙, respectively). Their location in the black hole mass - stellar mass plane is consistent with the distribution at low redshift, suggesting that the relation between black holes and their host galaxies was already in place less than a billion years after the Big Bang.

DOI: 10.1038/s41586-023-06345-5

Source: https://www.nature.com/articles/s41586-023-06345-5