The University of Tokyo · Physics and Astronomy
유이치 하리카네 교수의 연구실은 원시은하와 초기우주의 성간 환경을 탐색하는 데 초점을 맞춘 천체물리학 연구를 수행합니다. 특히 제임스 웹 우주망원경(JWST)을 활용한 고적색도 은하, 활성은하핵(AGN), 그리고 초기 은하의 별 형성 역사에 대한 정밀한 스펙트럼 분석을 통해 간접적으로나마 초기 우주의 물리적 조건을 규명하고자 합니다. 또한, ALMA를 통한 고주파수 방사선 및 먼 적외선 방출 측정을 통해 은하 내 가스와 먼지의 분포 및 화학 조성을 분석하는 데도 기여하고 있습니다.
Figures are computed from collected data and may differ slightly.
Abstract We conduct a comprehensive study on dropout galaxy candidates at z ∼ 9–16 using the first 90 arcmin 2 James Webb Space Telescope (JWST) Near Infrared Camera images taken by the early release observations (ERO) and early release science programs. With the JWST simulation images, we find that a number of foreground interlopers are selected with a weak photo- z determination (Δ χ 2 > 4). We thus carefully apply a secure photo -z selection criterion (Δ χ 2 > 9) and conventional color
Abstract We present the first statistical sample of faint type 1 AGNs at z > 4 identified by JWST/NIRSpec deep spectroscopy. Among the 185 galaxies at z spec = 3.8–8.9 confirmed with NIRSpec, our systematic search for broad-line emission reveals 10 type 1 AGNs at z = 4.015–6.936 whose broad component is only seen in the permitted H α line and not in the forbidden [O iii ] λ 5007 line that is detected with greater significance than H α . The broad H α line widths of FWHM ≃ 1000–6000 km s −1 su
Abstract We present new measurements of rest-UV luminosity functions and angular correlation functions from 4,100,221 galaxies at z ∼ 2–7 identified in the Subaru/Hyper Suprime-Cam survey and CFHT Large Area U -band Survey. The obtained luminosity functions at z ∼ 4–7 cover a very wide UV luminosity range of ∼ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.002</mml:mn> <mml:mo>–</mml:mo> <mml:mn>2000</mml:mn> <mml:msubsup> <mml:mrow> <mml:mi>L</mml:mi> </mm
Abstract We present our new Atacama Large Millimeter/Submillimeter Array (ALMA) observations targeting [O iii ]88 μ m, [C ii ]158 μ m, [N ii ]122 μ m, and dust-continuum emission for three Lyman break galaxies at z = 6.0293–6.2037, identified in the Subaru/Hyper Suprime-Cam survey. We clearly detect [O iii ] and [C ii ] lines from all of the galaxies at 4.3–11.8 σ levels, and identify multi-band dust-continuum emission in two of the three galaxies, allowing us to estimate infrared luminosities a
Abstract We present pure spectroscopic constraints on the UV luminosity functions and cosmic star formation rate (SFR) densities from 25 galaxies at z spec = 8.61–13.20. By reducing the JWST/NIRSpec spectra taken in multiple programs of Early Release Observation, Early Release Science, General Observer, and Director’s Discretionary Time observations with our analysis technique, we independently confirm 16 galaxies at z spec = 8.61–11.40, including new redshift determinations, and a bright interl
Abstract We present two bright galaxy candidates at z ∼ 12–13 identified in our H -dropout Lyman break selection with 2.3 deg 2 near-infrared deep imaging data. These galaxy candidates, selected after careful screening of foreground interlopers, have spectral energy distributions showing a sharp discontinuity around 1.7 μ m, a flat continuum at 2–5 μ m, and nondetections at <1.2 μ m in the available photometric data sets, all of which are consistent with a z > 12 galaxy. An ALMA program ta
We have obtained three-dimensional maps of the universe in $\sim200\times200\times80$ comoving Mpc$^3$ (cMpc$^3$) volumes each at $z=5.7$ and $6.6$ based on a spectroscopic sample of 179 galaxies that achieves $\gtrsim80$\% completeness down to the Ly$\alpha$ luminosity of $\log(L_{\rm Ly\alpha}/[\mathrm{erg\ s^{-1}}])=43.0$, based on our Keck and Gemini observations and the literature. The maps reveal filamentary large-scale structures and two remarkable overdensities made out of at least 44 an
Abstract We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at z ∼ 7–14. Our sample is composed of 60 galaxies at z spec ∼ 7–14, including recently confirmed galaxies at z spec = 12.34–14.18 with JWST, as well as new confirmations at z spec = 6.583–7.643 with −24 < M UV < −21 mag using ALMA and Keck. Our JWST/NIRSpec observations have also revealed that very bright galaxy candidates at z ∼ 10–13 identified from ground-based telescope
We investigate Lya, [OIII]5007, Ha, and [CII]158um emission from 1124 galaxies at z=4.9-7.0. Our sample is composed of 1092 Lya emitters (LAEs) at z=4.9, 5.7, 6.6, and 7.0 identified by Subaru/Hyper Suprime-Cam (HSC) narrowband surveys covered by Spitzer large area survey with Subaru/HSC (SPLASH) and 34 galaxies at z=5.148-7.508 with deep ALMA [CII]158um data in the literature. Fluxes of strong rest-frame optical lines of [OIII] and Ha (Hb) are constrained by significant excesses found in the SP
We present a first statistical sample of faint type-1 AGNs at $z>4$ identified by JWST/NIRSpec deep spectroscopy. Among the 185 galaxies at $z_\mathrm{spec}=3.8-8.9$ confirmed with NIRSpec, our systematic search for broad-line emission reveals 10 type-1 AGNs at $z=4.015-6.936$ whose broad component is only seen in the permitted H$α$ line and not in the forbidden [OIII]$λ$5007 line that is detected with greater significance than H$α$. The broad H$α$ line widths of $\mathrm{FWHM}\simeq1000-6000
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