先進科学センター

大栗 真宗

オオグリ マサムネ  (Masamune Oguri)

基本情報

所属
千葉大学 先進科学センター 教授
学位
博士(理学)(2004年7月 東京大学)

研究者番号
60598572
ORCID ID
 https://orcid.org/0000-0003-3484-399X
J-GLOBAL ID
201801017753358631
researchmap会員ID
B000310867

外部リンク

学歴

 3

主要な論文

 345
  • Yoshinobu Fudamoto, Fengwu Sun, Jose M. Diego, Liang Dai, Masamune Oguri, Adi Zitrin, Erik Zackrisson, Mathilde Jauzac, David J. Lagattuta, Eiichi Egami, Edoardo Iani, Rogier A. Windhorst, Katsuya T. Abe, Franz Erik Bauer, Fuyan Bian, Rachana Bhatawdekar, Thomas J. Broadhurst, Zheng Cai, Chian Chou Chen, Wenlei Chen, Seth H. Cohen, Christopher J. Conselice, Daniel Espada, Nicholas Foo, Brenda L. Frye, Seiji Fujimoto, Lukas J. Furtak, Miriam Golubchik, Tiger Yu Yang Hsiao, Jean Baptiste Jolly, Hiroki Kawai, Patrick L. Kelly, Anton M. Koekemoer, Kotaro Kohno, Vasily Kokorev, Mingyu Li, Zihao Li, Xiaojing Lin, Georgios E. Magdis, Ashish K. Meena, Anna Niemiec, Armin Nabizadeh, Johan Richard, Charles L. Steinhardt, Yunjing Wu, Yongda Zhu, Siwei Zou
    Nature Astronomy 9(3) 428-437 2025年3月  
    Strong gravitational magnification enables the detection of faint background sources and allows researchers to resolve their internal structures and even identify individual stars in distant galaxies. Highly magnified individual stars are useful in various applications, including studies of stellar populations in distant galaxies and constraining dark matter structures in the lensing plane. However, these applications have been hampered by the small number of individual stars observed, as typically one or a few stars are identified from each distant galaxy. Here, we report the discovery of more than 40 microlensed stars in a single galaxy behind Abell 370 at redshift of 0.725 (dubbed ‘the Dragon arc’) when the Universe was half of its current age, using James Webb Space Telescope observations with the time-domain technique. These events were found near the expected lensing critical curves, suggesting that these are magnified stars that appear as transients from intracluster stellar microlenses. Through multi-wavelength photometry, we constrained their stellar types and found that many of them are consistent with red giants or supergiants magnified by factors of hundreds. This finding reveals a high occurrence of microlensing events in the Dragon arc and demonstrates that time-domain observations by the James Webb Space Telescope could lead to the possibility of conducting statistical studies of high-redshift stars.
  • Masamune Oguri, Satoshi Miyazaki
    Proceedings of the Japan Academy Series B: Physical and Biological Sciences 101(3) 129-142 2025年  
    Clusters of galaxies can be identified from the peaks in weak lensing aperture mass maps constructed from weak lensing shear catalogs. Such purely gravitational cluster selection differs considerably from traditional cluster selection based on the baryonic properties of clusters. In this review, we present the basics and applications of weak lensing shear-selected cluster samples. Detailed studies of the baryonic properties of shear-selected clusters shed new light on cluster astrophysics. The purely gravitational selection indicates that the selection function can be quantified more easily and robustly, which is crucial for deriving accurate cosmological constraints from the abundance of shear-selected clusters. Recent advances in shear-selected cluster studies are driven by the Subaru Hyper Suprime-Cam survey, in which more than 300 shear-selected clusters with a signal-to-noise ratio?> 5 were identified. It is argued that various systematic effects in cosmological analysis can be mitigated by carefully selecting the setup of the analysis, including the selection of kernel functions and the source galaxy sample.
  • Angela Adamo, Larry D. Bradley, Eros Vanzella, Adélaïde Claeyssens, Brian Welch, Jose M. Diego, Guillaume Mahler, Masamune Oguri, Keren Sharon, Abdurro’uf, Tiger Yu Yang Hsiao, Xinfeng Xu, Matteo Messa, Augusto E. Lassen, Erik Zackrisson, Gabriel Brammer, Dan Coe, Vasily Kokorev, Massimo Ricotti, Adi Zitrin, Seiji Fujimoto, Akio K. Inoue, Tom Resseguier, Jane R. Rigby, Yolanda Jiménez-Teja, Rogier A. Windhorst, Takuya Hashimoto, Yoichi Tamura
    Nature 632(8025) 513-516 2024年8月15日  
    The Cosmic Gems arc is among the brightest and highly magnified galaxies observed at redshift z ≈ 10.2 (ref. 1). However, it is an intrinsically ultraviolet faint galaxy, in the range of those now thought to drive the reionization of the Universe2–4. Hitherto the smallest features resolved in a galaxy at a comparable redshift are between a few hundreds and a few tens of parsecs (pc)5,6. Here we report JWST observations of the Cosmic Gems. The light of the galaxy is resolved into five star clusters located in a region smaller than 70 pc. They exhibit minimal dust attenuation and low metallicity, ages younger than 50 Myr and intrinsic masses of about 106M⊙. Their lensing-corrected sizes are approximately 1 pc, resulting in stellar surface densities near 105M⊙ pc−2, three orders of magnitude higher than typical young star clusters in the local Universe7. Despite the uncertainties inherent to the lensing model, they are consistent with being gravitationally bound stellar systems, that is, proto-globular clusters. We conclude that star cluster formation and feedback likely contributed to shaping the properties of galaxies during the epoch of reionization.
  • Patrick L. Kelly, Steven Rodney, Tommaso Treu, Masamune Oguri, Wenlei Chen, Adi Zitrin, Simon Birrer, Vivien Bonvin, Luc Dessart, Jose M. Diego, Alexei V. Filippenko, Ryan J. Foley, Daniel Gilman, Jens Hjorth, Mathilde Jauzac, Kaisey Mandel, Martin Millon, Justin Pierel, Keren Sharon, Stephen Thorp, Liliya Williams, Tom Broadhurst, Alan Dressler, Or Graur, Saurabh Jha, Curtis McCully, Marc Postman, Kasper Borello Schmidt, Brad E. Tucker, Anja von der Linden
    Science 380(6649) abh1322 2023年6月9日  
    The gravitationally lensed supernova Refsdal appeared in multiple images produced through gravitational lensing by a massive foreground galaxy cluster. After the supernova appeared in 2014, lens models of the galaxy cluster predicted that an additional image of the supernova would appear in 2015, which was subsequently observed. We use the time delays between the images to perform a blinded measurement of the expansion rate of the Universe, quantified by the Hubble constant (H0). Using eight cluster lens models, we infer H0 = 64:8+4.4-4.3 kilometers per second per megaparsec. Using the two models most consistent with the observations, we find H0 = 66:6+4.1-3.3 kilometers per second per megaparsec. The observations are best reproduced by models that assign dark-matter halos to individual galaxies and the overall cluster.
  • Yu Ching Chen, Xin Liu, Adi Foord, Yue Shen, Masamune Oguri, Nianyi Chen, Tiziana Di Matteo, Miguel Holgado, Hsiang Chih Hwang, Nadia Zakamska
    Nature 616(7955) 45-49 2023年4月  
    Galaxy mergers produce pairs of supermassive black holes (SMBHs), which may be witnessed as dual quasars if both SMBHs are rapidly accreting. The kiloparsec (kpc)-scale separation represents a physical regime sufficiently close for merger-induced effects to be important1 yet wide enough to be directly resolvable with the facilities currently available. Whereas many kpc-scale, dual active galactic nuclei—the low-luminosity counterparts of quasars—have been observed in low-redshift mergers2, no unambiguous dual quasar is known at cosmic noon (z ≈ 2), the peak of global star formation and quasar activity3,4. Here we report multiwavelength observations of Sloan Digital Sky Survey (SDSS) J0749 + 2255 as a kpc-scale, dual-quasar system hosted by a galaxy merger at cosmic noon (z = 2.17). We discover extended host galaxies associated with the much brighter compact quasar nuclei (separated by 0.46″ or 3.8 kpc) and low-surface-brightness tidal features as evidence for galactic interactions. Unlike its low-redshift and low-luminosity counterparts, SDSS J0749 + 2255 is hosted by massive compact disk-dominated galaxies. The apparent lack of stellar bulges and the fact that SDSS J0749 + 2255 already follows the local SMBH mass–host stellar mass relation, suggest that at least some SMBHs may have formed before their host stellar bulges. While still at kpc-scale separations where the host-galaxy gravitational potential dominates, the two SMBHs may evolve into a gravitationally bound binary system in around 0.22 Gyr.
  • Hayley Williams, Patrick L. Kelly, Wenlei Chen, Gabriel Brammer, Adi Zitrin, Tommaso Treu, Claudia Scarlata, Anton M. Koekemoer, Masamune Oguri, Yu Heng Lin, Jose M. Diego, Mario Nonino, Jens Hjorth, Danial Langeroodi, Tom Broadhurst, Noah Rogers, Ismael Perez-Fournon, Ryan J. Foley, Saurabh Jha, Alexei V. Filippenko, Lou Strolger, Justin Pierel, Frederick Poidevin, Lilan Yang
    Science 380(6643) 416-420 2023年4月  
    Ultraviolet light from early galaxies is thought to have ionized gas in the intergalactic medium. However, there are few observational constraints on this epoch because of the faintness of those galaxies and the redshift of their optical light into the infrared. We report the observation, in JWST imaging, of a distant galaxy that is magnified by gravitational lensing. JWST spectroscopy of the galaxy, at rest-frame optical wavelengths, detects strong nebular emission lines that are attributable to oxygen and hydrogen. The measured redshift is z = 9.51 ± 0.01, corresponding to 510 million years after the Big Bang. The galaxy has a radius of 16.2 +4.6-7.2 parsecs, which is substantially more compact than galaxies with equivalent luminosity at z ~ 6 to 8, leading to a high star formation rate surface density.
  • Wenlei Chen, Patrick L. Kelly, Masamune Oguri, Thomas J. Broadhurst, Jose M. Diego, Najmeh Emami, Alexei V. Filippenko, Tommaso L. Treu, Adi Zitrin
    Nature 611(7935) 256-259 2022年11月1日  
    The core-collapse supernova of a massive star rapidly brightens when a shock, produced following the collapse of its core, reaches the stellar surface. As the shock-heated star subsequently expands and cools, its early-time light curve should have a simple dependence on the size of the progenitor1 and therefore final evolutionary state. Measurements of the radius of the progenitor from early light curves exist for only a small sample of nearby supernovae2-14, and almost all lack constraining ultraviolet observations within a day of explosion. The several-day time delays and magnifying ability of galaxy-scale gravitational lenses, however, should provide a powerful tool for measuring the early light curves of distant supernovae, and thereby studying massive stellar populations at high redshift. Here we analyse individual rest-frame exposures in the ultraviolet to the optical taken with the Hubble Space Telescope, which simultaneously capture, in three separate gravitationally lensed images, the early phases of a supernova at redshift z ≈ 3 beginning within 5.8 ± 3.1 hours of explosion. The supernova, seen at a lookback time of approximately 11.5 billion years, is strongly lensed by an early-type galaxy in the Abell 370 cluster. We constrain the pre-explosion radius to be [Formula: see text] solar radii, consistent with a red supergiant. Highly confined and massive circumstellar material at the same radius can also reproduce the light curve, but because no similar low-redshift examples are known, this is unlikely.
  • Masamune Oguri, Ryuichi Takahashi
    Physical Review D 106(4) 2022年8月15日  
    We discuss how small-scale density perturbations on the Fresnel scale affect amplitudes and phases of gravitational waves that are magnified by gravitational lensing in geometric optics. We derive equations that connect the small-scale density perturbations with the amplitude and phase fluctuations to show that such perturbative wave optics effects are significantly boosted in the presence of macro model magnifications such that amplitude and phase fluctuations can easily be observed for highly magnified gravitational waves. We discuss expected signals due to microlensing by stars, dark matter substructure, fuzzy dark matter, and primordial black holes.

主要なMISC

 21

主要な書籍等出版物

 2
  • 大栗, 真宗
    朝倉書店 2025年3月 (ISBN: 9784254135336)

主要な担当経験のある科目(授業)

 11

主要な共同研究・競争的資金等の研究課題

 16