表題番号：2025R-062 日付：2026/03/30
研究課題JWSTで解き明かす超巨大ブラックホールと母銀河の初期成長史
研究者所属（当時） 資格 氏名
（代表者） 高等研究所 講師 尾上　匡房
研究成果概要
This fiscal year, I focused on observational studies of the co-evolution of supermassive black holes and their host galaxies in the early universe, primarily using my PI observations of the James Webb Space Telescope (JWST), a 6.5-meter space infrared telescope. In particular, in my first-author paper published in Nature Astronomy (Onoue et al. 2025), I provided new insights into the connection between black hole growth and galaxy evolution only 900 million years after the Big Bang, based on the detection and stellar population analysis of host galaxies of low-luminosity quasars at redshift 6. This result was obtained from 12 quasars that were originally discovered by Subaru Telescope.

For one object in particular, J2236+0032, I was able to capture a phase in which the host galaxy had already matured, reaching a stellar mass of 10 billion solar masses, and its star formation had been quenched by an accreting massive black hole residing its center. This study is the first in the world to achieve such a detailed characterization of the properties of distant galaxies hidden beneath the glare of luminous quasars, which were only possible down to redshift 1-2. 

As a key result of the JWST project, we report the distribution of the distant quasars and their host galaxies, where we advocate that the stellar to BH mass relation does not largely evolve from redshift 6 to 0, namely the current universe. We are now planning to extend this study with a x4 larger sample in order to more accurately constrain the mean mass ratio and its intrinsic scatter, which may contain information of the seed black hole formation.

In addition, I led new observations with the Subaru Telescope's new instrument, Prime Focus Spectrograph (PFS). The target was a proto-cluster field around a luminous quasar at z=6.6. Taking advantage of the PFS's capability to perform multi-fiber spectroscopy over R~200 coming mega parsec at z~6, I will use this data to confirm the richest galaxy environment supplying cold gas to a monster black hole.

In recognition of these world-leading observational achievements as well as my past research activity, I was awarded the Young Astronomer Award of the Astronomical Society of Japan.