| 研究課題/領域番号 |
22H01262
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| 配分区分 | 補助金 |
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| 研究機関 | 東京大学 |
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研究代表者 |
SILVERMAN John 東京大学, カブリ数物連携宇宙研究機構, 教授 (90573030)
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| 研究分担者 |
泉 拓磨 国立天文台, アルマプロジェクト, 助教 (40792932)
松岡 良樹 愛媛大学, 宇宙進化研究センター, 准教授 (60547545)
Ding Xuheng 東京大学, カブリ数物連携宇宙研究機構, 特任研究員 (60895986)
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| 研究期間 (年度) |
2022-04-01 – 2025-03-31
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| キーワード | supermassive black holes / galaxy evolution / JWST |
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| 研究実績の概要 |
Supermassive black holes (SMBHs) and their host galaxies co-evolve over the last eight billion years of cosmic time (z < 2) as evident by their non-evolving mass ratio. This coupled growth is likely due to gas regulation from the SMBH itself or supernova triggered through ongoing star formation. We are determining whether the mass ratio M_BH/M_galaxy is truly universal (i.e., constant at all redshifts) by measuring this mass ratio in the early Universe (z ~ 6). This is achieved through our approved James Webb Space Telescope (JWST) Cycle 1 Program that targets 12 SHELLQs quasars at z ~ 6 from the HSC Subaru Strategic Program, with both imaging and spectroscopy. For the first time at z ~ 6, we are determining the (1) masses (and types) of galaxies hosting the first SMBHs, (2) their black hole masses based on the Balmer emission lines, and (3) the distribution functions of black hole mass and Eddington rate, all key to understanding the growth of early SMBHs. This analysis is being combined with our study of SMBHs at later cosmic times (1 < z < 3) to construct a full picture of the growth of galaxies and their black holes. This is accomplished using the COSMOS-Web, a JWST imaging survey of the COSMOS field. Both our SHELLQs program and COSMOS-Web are playing leading roles in quasar - host galaxy studies in the distant Universe.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
In FY2022, we have developed and tested our 2D image analysis tools with JWST Near-Infrared Camera (NIRCam) images from the public early-release science program (CEERS). We successfully decomposed the quasar and galaxy emission which resulted in the detection of the host galaxies of five quasars at z > 1.5 and full characterization of the in-orbit JWST point-spread function. This work has been published and presented at the first JWST conference at Space Telescope Science Institute. We also received the complete JWST data for two SHELLQs at z ~ 6 including NIRCam and Near-Infrared Spectrograph (NIRSpec) data that have been processed for science-grade measurements. For these two targets, we significantly detect the host galaxies for both quasars thus enabling a stellar mass measurement. This is a milestone for quasar-host galaxy studies since previous Hubble observations were unsuccessful. We also detect the broad emission lines with NIRSpec and measured their black hole mass. Surprisingly, stellar absorption feature are seen in one of the quasar hosts which indicate a recent burst of star formation. This first analysis has been submitted for publication. In addition, six out of 151 NIRCam images from COSMOS-Web have been taken and allowed us to assess the effectiveness of our 2D image decomposition analysis of JWST images for 50 AGN at z>1.
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| 今後の研究の推進方策 |
We are continuing with the planned research program. All JWST observations for the 12 SHELLQS z~6 QSOs will be delivered in FY2023. These include the NIRCam and NIRSpec data. We will complete the studies on the following: (1) the relation between black hole and galaxy mass, (2) constraints on the black hole mass function and Eddington rate distribution, (3) stellar populations of quasar host galaxies at z~6 and (4) role of galaxy mergers in quasar activity in the early Universe. In addition, new proposals will be submitted to JWST and ALMA to expand the breadth of the program in terms of sample size and spectral/spatial resolution. In FY2023, all observations with JWST/NIRCam will be completed and delivered for the COSMOS-Web program. These will provide the infrared imaging to decompose the emission of quasars up to z ~ 3 into the separate quasar and host galaxy light. We will report on the properties of the host galaxies and the mass relation between black hole and their host galaxy. Followup proposals to JWST and will be submitted to study in detail their stellar populations, gas content and large-scale environments. With the addition of similar analysis based on the Hyper Suprime-Cam Subaru Strategic Survey, a comprehensive picture of the joint black hole and galaxy growth using the SHELLQs and COSMOS-Web programs will be achieved.
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