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Fermi surface of PtCoO2 from quantum oscillations and electronic structure calculations

Physical Review B 2020年第19期101卷 195101-195101页

作者： F. Arnold M. Naumann H. Rosner N. Kikugawa D. Graf L. Balicas T. Terashima S. Uji H. Takatsu S. Khim A. P. Mackenzie E. Hassinger Max Planck Institute for Chemical Physics of Solids 01187 Dresden Germany Physik-Department Technische Universität München 85748 Garching Germany National Institute for Materials Science Tsukuba Ibaraki 305-0003 Japan National High Magnetic Field Laboratory Florida State University Tallahassee Florida 32310 USA Graduate School of Pure and Applied Sciences University of Tsukuba Tsukuba 305-8577 Japan Department of Physics Tokyo Metropolitan University Tokyo 192-0397 Japan Scottish Universities Physics Alliance School of Physics and Astronomy University of St. Andrews St. Andrews Fife KY16 9SS United Kingdom

The delafossite series of layered oxides includes some of the highest conductivity metals ever discovered. Of these, PtCoO2, with a room-temperature resistivity of 1.8 μΩcm for in-plane transport, is the most conducting of all. The high conduction takes place in triangular lattice Pt layers, separated by layers of Co-O octahedra, and the electronic structure is determined by the interplay of the two types of layers. We present a detailed study of quantum oscillations in PtCoO2, at temperatures down to 35 mK and magnetic fields up to 30 T. As for PdCoO2 and PdRhO2, the Fermi surface consists of a single cylinder with mainly Pt character and an effective mass close to the free-electron value. Due to Fermi-surface warping, two close-lying high frequencies are observed. Additionally, a pronounced difference frequency appears. By analyzing the detailed angular dependence of the quantum-oscillation frequencies, we establish the warping parameters of the Fermi surface. We compare these results to the predictions of first-principles electronic-structure calculations including spin-orbit coupling on Pt and Co and on-site correlation U on Co, and hence demonstrate that electronic correlations in the Co-O layers play an important role in determining characteristic features of the electronic structure of PtCoO2.

关键词： Electronic structure Fermi surface Transition metal oxides DFT+U Magnetization measurements de Haas-van Alphen effect

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High-efficiency and ultrastable solvent-free curable perovskite quantum dot inks for microLED and LED backlighting applications

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Nano Energy 2025年 142卷

作者： Loan Thi Ngo Yu-Ting Huang Cheng-Chieh Chang Hemant Verma Yen-Huei Lin Ching-Tai Kuo Ying-Chih Liao Chao-Cheng Kaun Ren-Jei Chung Ru-Shi Liu Department of Chemistry National Taiwan University Taipei 106 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica and National Taiwan University Academia Road 128 Nankang Taipei 115 Taiwan Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei 106 Taiwan Department of Physics National Taiwan University Taipei 106 Taiwan Research Center for Applied Sciences Academia Sinica Academia Road 128 Section 2 Nangang Taipei 11529 Taiwan Department of Chemical Engineering National Taiwan University Taipei 106 Taiwan

Metal lead halide perovskite quantum dots (PeQDs) exhibit exceptional optoelectronic properties, showing promise as components for solar cells, lighting, display, and anticounterfeiting devices. However, the instability of PeQDs, along with synthesis and storage methods that rely on hazardous solvents, has limited their potential for commercial applications. To overcome these obstacles, we introduce a solvent-free method for fabricating high-quality green and red CsPbX 3 PeQD (X = Br, I) ink. Using a fluidic system, we first obtained super-high photoluminescence quantum yield PeQDs (92 % for red CsPb(Br,I) 3 , and nearly 100 % for green CsPbBr 3 PeQDs). The uniform nonsolvent PeQD ink is fabricated by modifying the as-formed PeQD surface with a mixture of trimethoxysilane and 3-(trimethoxysilyl)propyl methacrylate silane coupling agents to form PeQDs@silane, then dispersing the PeQDs@silane in a UV-curable 1,6-hexanediol diacrylate monomer. Our solvent-free PeQD ink exhibits bright and stable green and red emissions with long-term stability, retaining 100 % PL intensity after 115 days for CsPbBr 3 and 78 days for CsPb(Br,I) 3 . The environment-friendly ink enables highly uniform and bright films for LED backlighting and patterns for micro-LED applications. With color coordinates near the red and green reference values, the PeQD films demonstrate a remarkable 100.28 % color gamut coverage in comparison with Rec. 2020. This scalable and environmentally friendly method provides a safer alternative than conventional solvent-based PeQD ink.

关键词： Nanocrystals

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Quantum criticality in Ising chains with random hyperuniform couplings

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Physical Review B 2019年第13期100卷 134206-134206页

作者： P. J. D. Crowley C. R. Laumann S. Gopalakrishnan Physics Department Boston University Boston Massachusetts 02215 USA Department of Physics and Astronomy CUNY College of Staten Island Staten Island New York 10314 USA Physics Program and Initiative for the Theoretical Sciences The Graduate Center CUNY New York New York 10016 USA

We study quantum phase transitions in transverse-field Ising spin chains in which the couplings are random but hyperuniform, in the sense that their large-scale fluctuations are suppressed. We construct a one-parameter family of disorder models in which long-wavelength fluctuations are increasingly suppressed as a parameter α is tuned. For α=0, one recovers the familiar infinite-randomness critical point. For 0<α<1, we find a line of infinite-randomness critical points with continuously varying critical exponents; however, the Griffiths phases that flank the critical point at α=0 are absent at any α>0. When α>1, randomness is a dangerously irrelevant perturbation at the clean Ising critical point, leading to a state we call the critical Ising insulator. In this state, thermodynamics and equilibrium correlation functions behave as in the clean system. However, all finite-energy excitations are localized, thermal transport vanishes, and autocorrelation functions remain finite in the long-time limit. We characterize this line of hyperuniform critical points using a combination of perturbation theory, renormalization-group methods, and exact diagonalization.

关键词： Magnetic phase transitions Quantum criticality Random & disordered media Critical exponents Critical phenomena Ising model Random field Ising model

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The Astrometric Animation of Water Masers towards the Mira Variable BX Cam

arXiv

引用

arXiv 2022年

作者： Xu, Shuangjing Imai, Hiroshi Yun, Youngjoo Zhang, Bo Rioja, María J. Dodson, Richard Cho, Se-Hyung Kim, Jaeheon Cui, Lang Sobolev, Andrey M. Chibueze, James O. Kim, Dong-Jin Amada, Kei Nakashima, Jun-Ichi Orosz, Gabor Oyadomari, Miyako Oh, Sejin Yonekura, Yoshinori Sun, Yan Mai, Xiaofeng Zhang, Jingdong Wen, Shiming Jung, Taehyun Korea Astronomy and Space Science Institute 776 Daedeok-daero Yuseong-gu Daejeon34055 Korea Republic of Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Graduate School of Science and Engineering Kagoshima University 1-21-35 Korimoto Kagoshima890-0065 Japan Amanogawa Galaxy Astronomy Research Center Graduate School of Science and Engineering Kagoshima University 1-21-35 Korimoto Kagoshima890-0065 Japan Center for General Education Institute for Comprehensive Education Kagoshima University 1-21-30 Korimoto Kagoshima890-0065 Japan ICRAR M468 The University of Western Australia 35 Stirling Hwy CrawleyWA6009 Australia CSIRO Astronomy and Space Science PO Box 1130 BentleyWA6102 Australia Alfonso XII 3 y 5 Madrid28014 Spain Astronomy program Department of Physics and Astronomy Seoul National University Seoul08826 Korea Republic of Republic of Korea Korea Astronomy and Space Science Institute Yuseonggu Daejeon34055 Korea Republic of Xinjiang Astronomical Observatory Chinese Academy of Sciences 150 Science 1-Street Urumqi830011 China Ural Federal University 19 Mira Street Ekaterinburg620002 Russia Centre for Space Research North-West University Potchefstroom2520 South Africa Department of Physics and Astronomy Faculty of Physical Sciences University of Nigeria Carver Building 1 University Road Nsukka Nigeria Massachusetts Institute of Technology Haystack Observatory 99 Millstone Road WestfordMA01886 United States Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany School of Physics and Astronomy Sun Yat-sen University 2 Daxue Road Tangjia Guangdong Province Zhuhai China Joint Institute for VLBI ERIC Oude Hoogeveensedijk 4 Dwingeloo7991PD Netherlands Center for Astronomy Ibaraki University 2-1-1 Bunkyo Ibaraki Mito310-8512 Japan Yuquan Rd. Shijingshan Beijing100049 China

We report VLBI monitoring observations of the 22 GHz water (H2O) masers around the Mira variable BX Cam, which were carried out as a part of the EAVN Synthesis of Stellar Maser Animations (ESTEMA) project. Data of 37 epochs in total were obtained from 2018 May to 2021 June with a time interval of 3–4 weeks, spanning approximately three stellar pulsation periods (P =∼440 d). In particular, the dual-beam system equipped on the VERA stations was used to measure the kinematics and parallaxes of the H2O maser features. The measured parallax, π = 1.79 ± 0.08 mas, is consistent with Gaia EDR3 and previously measured VLBI parallaxes within a 1-σ error level. The position of the central star was estimated, based on both the Gaia EDR3 data and the center position of the ring-like 43 GHz silicon-monoxide (SiO) maser distribution imaged with the KVN. The three-dimensional H2O maser kinematics indicates that the circumstellar envelope is expanding at a velocity of 13 ± 4 km s−1, while there are asymmetries in both the spatial and velocity distributions of the maser features. Furthermore, the H2O maser animation achieved by our dense monitoring program manifests the propagation of shock waves in the circumstellar envelope of BX Cam. © 2022, CC BY.

关键词： Stars

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High Resolution Imaging of Hg/Se Aggregates in the Brain of Wild Terrestrial Species (Small Indian Mongoose) – Insight into Intracellular Hg Detoxification

SSRN

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SSRN 2023年

作者： Devabathini, Pavani Fischer, Darrell L. Chen, Si Pattammattel, Ajith Bury, Gabriel Antipova, Olga Huang, Xiaojing Chu, Yong S. Horai, Sawako Pushkar, Yulia Department of Physics and Astronomy Purdue University West LafayetteIN47907 United States National Synchrotron Light Source II Brookhaven National Laboratory UptonNY11973 United States XSD Argonne National Laboratory 9700 S. Cass Ave. ArgonneIL60439 United States Department of Life and Environmental Agricultural Science Tottori University Tottori680-8550 Japan Harvard Graduate Program in Biophysics Harvard 2 University HMS Campus 240/250 Longwood Avenue Seeley G. Mudd Bldg. C Room 204c BostonMA02115 United States Environmental Health Section Dept. Environment and Public Health National Institute for Minamata Disease Ministry of the Environment 4058-18 Hama Minamata City Kumamoto867-0008 Japan

Exposure to Hg in humans is highly neurotoxic. However, Hg biomagnification in marine mammals and predatory fish seems not to affect the species health. Significantly less is known about the response of wild terrestrial species to elevated environmental Hg. Elevated Hg content on par with organ level concentrations in marine mammals has been found in the liver of wild small Indian mongoose. This indicates high levels of exposure and potential biomagnification in analysed animal populations. Synchrotron X-ray fluorescence microscopy revealed significant Hg content in the mongoose brain, where micron-sized Hg-rich deposits were preferentially detected in the cells of the choroid plexus and astrocytes of the subventricular wall. Hg content in these aggregates exhibited significant spatial correlation (r ~ 0.9-0.8) with selenium (Se), suggesting the interaction of two elements. Hg aggregates do not co-localize with lysosomes. The low Hg density inside aggregates indicates diffuse Hg binding to a Se-containing biomolecule rather than much denser HgSe nanoparticles proposed to form in other species. Se K-edge XANES did not match spectra of HgSe material. Our data highlight the susceptibility of small Indian mongoose population to Hg pollution and provide evidence on the adaptation in the form of a Se-based detoxification mechanism sequestering Hg into intracellular aggregates. © 2023, The Authors. All rights reserved.

关键词： Selenium

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International comparison of optical frequencies with transportable optical lattice clocks

arXiv

引用

arXiv 2024年

作者： Amy-Klein, Anne Benkler, Erik Blondé, Pascal Bongs, Kai Cantin, Etienne Chardonnet, Christian Denker, Heiner Dörscher, Sören Feng, Chen-Hao Gaudron, Jacques-Olivier Gill, Patrick Hill, Ian R. Huang, Wei Johnson, Matthew Y.H. Kale, Yogeshwar B. Katori, Hidetoshi Klose, Joshua Kronjäger, Jochen Kuhl, Alexander Targat, Rodolphe Le Lisdat, Christian Lopez, Olivier Lücke, Tim Mazouth, Maxime Mukherjee, Shambo Nosske, Ingo Pointard, Benjamin Pottie, Paul-Eric Schioppo, Marco Singh, Yeshpal Stahl, Kilian Takamoto, Masao Tønnes, Mads Tunesi, Jacob Ushijima, Ichiro Vishwakarma, Chetan Université Sorbonne Paris Nord CNRS 99 Avenue Jean-Baptiste Clément Villetaneuse93430 France Physikalisch-Technische Bundesanstalt Bundesallee 100 Braunschweig38116 Germany LNE-SYRTE Observatoire de Paris PSL Research University CNRS Sorbonne Universités UPMC University of Paris 06 61 Avenue de l'Observatoire Paris75014 France Institut für Quantentechnologien Wilhelm-Runge-Straße 10 Ulm89081 Germany Institut für Erdmessung Leibniz Universität Hannover Schneiderberg 50 Hannover30167 Germany National Physical Laboratory Hampton Road TeddingtonTW11 0LW United Kingdom School of Physics and Astronomy University of Birmingham BirminghamB15 2TT United Kingdom Department of Applied Physics Graduate School of Engineering The University of Tokyo Bunkyo-ku Tokyo113-8656 Japan Quantum Metrology Laboratory RIKEN Saitama Wako351-0198 Japan Space-Time Engineering Research Team RIKEN Center for Advanced Photonics Saitama Wako351-0198 Japan

Optical clocks have improved their frequency stability and estimated accuracy1,2,3,4,5,6,7 by more than two orders of magnitude over the best caesium microwave clocks that realise the SI second. Accordingly, an optical redefinition of the second has been widely discussed8,9,10, prompting a need for the consistency of optical clocks to be verified worldwide8,10. While satellite frequency links are sufficient to compare microwave clocks, a suitable method for comparing high-performance optical clocks over intercontinental distances is missing. Furthermore, remote comparisons over frequency links face fractional uncertainties of a few 10−18 due to imprecise knowledge of each clock’s relativistic redshift, which stems from uncertainty in the geopotential determined at each distant location. Here, we report a landmark campaign towards the era of optical clocks, where, for the first time, state-of-the-art transportable optical clocks from Japan and Europe are brought together to demonstrate international comparisons that require neither a high-performance frequency link nor information on the geopotential difference between remote sites. Conversely, the reproducibility of the clocks after being transported between countries was sufficient to determine geopotential height offsets at the level of 4 cm. Our campaign paves the way for redefining the SI second and has a significant impact on various applications, including tests of general relativity11, geodetic sensing for geosciences, precise navigation, and future timing networks. Copyright © 2024, The Authors. All rights reserved.

关键词： Relativity

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North Ecliptic Pole merging galaxy catalogue

arXiv

引用

arXiv 2022年

作者： Pearson, William J. Suelves, L.E. Ho, S.C.-C. Oi, N. Brough, S. Holwerda, B.W. Hopkins, A.M. Huang, T.-C. Hwang, H.S. Kelvin, L.S. Kim, S.J. López-Sánchez, Á.R. Malek, K. Pearson, C. Poliszczuk, A. Pollo, A. Rodriguez-Gomez, V. Shim, H. Toba, Y. Wang, L. National Centre for Nuclear Research Pasteura 7 Warszawa02-093 Poland Institute of Astronomy National Tsing Hua University 101 Section 2. Kuang-Fu Road Hsinchu30013 Taiwan Faculty of Science Division II Liberal Arts Tokyo University of Science 1-3 Kagurazaka Shinjuku-ku Tokyo162-8601 Japan School of Physics University of New South Wales NSW2052 Australia Department of Physics and Astronomy University of Louisville 102 Natural Science Building LouisvilleKY40292 United States Australian Astronomical Optics Macquarie University 105 Delhi Rd North RydeNSW2113 Australia Department of Space and Astronautical Science Graduate University for Advanced Studies SOKENDAI Shonankokusaimura Hayama Miura District Kanagawa240-0193 Japan Institute of Space and Astronautical Science Japan Aerospace Exploration Agency 3-1-1 Yoshinodai Chuo-ku Kanagawa Sagamihara252-5210 Japan Astronomy Program Department of Physics and Astronomy Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of Department of Astrophysical Sciences Princeton University 4 Ivy Lane Princeton NJ08544 United States Department of Physics and Astronomy Macquarie University NSW2109 Australia Australia Aix Marseille Univ. CNRS CNES LAM Marseille France The Open University Milton KeynesMK7 6AA United Kingdom RAL Space Rutherford Appleton Laboratory Chilton Didcot Oxfordshire OX11 0QX United Kingdom Oxford Astrophysics University of Oxford Keble Rd OxfordOX1 3RH United Kingdom Instituto de Radioastronomía y Astrofísica Universidad Nacional Autónoma de México A.P. 72-3 Morelia58089 Mexico Department of Earth Science Education Kyungpook National University Daegu41566 Korea Republic of Department of Astronomy Kyoto University Kitashirakawa-Oiwake-cho Sakyo-ku Kyoto606-8502 Japan Academia Sinica Institute of Astronomy and Astrophysics 11F of Astronomy-Mathematics Building AS/NTU No.1 Section 4 Roosevelt Road Taipei10617 Taiwan Research Center

关键词： Merging

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Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES 2344+514

arXiv

引用

arXiv 2023年

作者： Abe, H. Abe, S. Acciari, V.A. Agudo, I. Aniello, T. Ansoldi, S. Antonelli, L.A. Arbet Engels, A. Arcaro, C. Artero, M. Asano, K. Baack, D. Babić, A. Baquero, A. Barres de Almeida, U. Batković, I. Baxter, J. Becerra González, J. Bernardini, E. Bernete, J. Berti, A. Besenrieder, J. Bigongiari, C. Biland, A. Blanch, O. Bonnoli, G. Bošnjak, Ž. Burelli, I. Busetto, G. Campoy-Ordaz, A. Carosi, A. Carosi, R. Carretero-Castrillo, M. Castro-Tirado, A.J. Chai, Y. Cifuentes, A. Cikota, S. Colombo, E. Contreras, J.L. Cortina, J. Covino, S. D’Amico, G. D’Ammando, F. D’Elia, V. Da Vela, P. Dazzi, F. De Angelis, A. De Lotto, B. Del Popolo, A. Delfino, M. Delgado, J. Delgado Mendez, C. Depaoli, D. Di Pierro, F. Di Venere, L. Dominis Prester, D. Dorner, D. Doro, M. Elsaesser, D. Emery, G. Escudero, J. Fariña, L. Fattorini, A. Foffano, L. Font, L. Fukami, S. Fukazawa, Y. García López, R.J. Gasparyan, S. Gaug, M. Giesbrecht Paiva, J.G. Giglietto, N. Giordano, F. Gliwny, P. Grau, R. Green, J.G. Hadasch, D. Hahn, A. Heckmann, L. Herrera, J. Hrupec, D. Hütten, M. Imazawa, R. Inada, T. Iotov, R. Ishio, K. Jiménez Martínez, I. Jormanainen, J. Kerszberg, D. Kluge, G.W. Kobayashi, Y. Kouch, P.M. Kubo, H. Kushida, J. Láinez Lezáun, M. Lamastra, A. Leone, F. Lindfors, E. Linhoff, L. Lombardi, S. Longo, F. López-Moya, M. López-Oramas, A. Loporchio, S. Lorini, A. Machado de Oliveira Fraga, B. Majumdar, P. Makariev, M. Maneva, G. Mang, N. Manganaro, M. Mariotti, M. Martínez, M. Martínez-Chicharro, M. Mas-Aguilar, A. Mazin, D. Menchiari, S. Mender, S. Miceli, D. Miener, T. Miranda, J.M. Mirzoyan, R. Molero González, M. Molina, E. Mondal, H.A. Moralejo, A. Morcuende, D. Nakamori, T. Nanci, C. Neustroev, V. Nigro, C. Nikolić, L. Nishijima, K. Njoh Ekoume, T. Noda, K. Nozaki, S. Ohtani, Y. Okumura, A. Otero-Santos, J. Paiano, S. Palatiello, M. Paneque, D. Paoletti, R. Paredes, J.M. Pavlović, D. Persic, M. Pihet, M. Pirola, G. Podobnik, F. Prada Moroni, P.G. The University of Tokyo Chiba Kashiwa277-8582 Japan Instituto de Astrofísica de Canarias Dpto. de Astrofísica Universidad de La Laguna Tenerife La LagunaE-38200 Spain Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n Granada18008 Spain RomeI-00136 Italy Università di Udine INFN Trieste UdineI-33100 Italy Max-Planck-Institut für Physik MünchenD-80805 Germany Università di Padova INFN PadovaI-35131 Italy The Barcelona InsINAF - Istituto di Radioastronomia Via Gobetti 101 BolognaI-40129 Italy Bellaterra BarcelonaE-08193 Spain Technische Universität Dortmund DortmundD-44221 Germany Zagreb10000 Croatia IPARCOS Institute EMFTEL Department Universidad Complutense de Madrid MadridE-28040 Spain Rio de Janeiro22290-180 Brazil Centro de Investigaciones Energéticas Medioambientales y Tecnológicas MadridE-28040 Spain ETH Zürich ZürichCH-8093 Switzerland Departament de Física CERES-IEEC Universitat Autònoma de Barcelona BellaterraE-08193 Spain Università di Pisa INFN Pisa PisaI-56126 Italy Universitat de Barcelona ICCUB IEEC-UB BarcelonaE-08028 Spain Department for Physics and Technology University of Bergen Norway INFN MAGIC Group: INFN Sezione di Catania Dipartimento di Fisica e Astronomia University of Catania CataniaI-95123 Italy INFN MAGIC Group: INFN Sezione di Torino Università degli Studi di Torino TorinoI-10125 Italy INFN MAGIC Group: INFN Sezione di Bari Dipartimento Interateneo di Fisica Università e del Politecnico di Bari BariI-70125 Italy Croatian MAGIC Group University of Rijeka Faculty of Physics Rijeka51000 Croatia University of Geneva Chemin d’Ecogia 16 VersoixCH-1290 Switzerland Japanese MAGIC Group: Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima739-8526 Japan Armenian MAGIC Group: ICRANet-Armenia Yerevan0019 Armenia University of Lodz Faculty of Physics and Applied Informatics Department of Astrophysics Lodz90-236 Pola

Aims. The BL Lac 1ES 2344+514 is known for temporary extreme properties (e.g., a shift of the synchrotron spectral energy distribution (SED) peak energy νsynch,p above 1 keV). While those extreme states were so far observed only during high flux levels, additional multi-year observing campaigns are required to achieve a coherent picture. Here, we report the longest investigation of the source from radio to very high energy (VHE) performed so far, focusing on a systematic characterisation of the intermittent extreme states. Methods. We organised a monitoring campaign covering a 3-year period from 2019 to 2021. More than ten instruments participated in the observations in order to cover the emission from radio to VHE. In particular, sensitive X-ray measurements by XMM-Newton, NuSTAR, and AstroSat took place simultaneously with multi-hour MAGIC observations, providing an unprecedented constraint of the two SED components for this blazar. Results. While our results confirm that 1ES 2344+514 typically exhibits νsynch,p > 1 keV during elevated flux periods, we also find periods where the extreme state coincides with low flux activity. A strong spectral variability thus happens in the quiescent state, and is likely caused by an increase of the electron acceleration efficiency without a change in the electron injection luminosity. On the other hand, we also report a strong X-ray flare (among the brightest for 1ES 2344+514) without a significant shift of νsynch,p. During this particular flare, the X-ray spectrum is among the softest of the campaign. It unveils complexity in the spectral evolution, where the common "harder-when-brighter" trend observed in BL Lacs is violated. By combining Swift-XRT and Swift-UVOT measurements during a low and hard X-ray state, we find an excess of the UV flux with respect to an extrapolation of the X-ray spectrum to lower energies. This "UV excess" implies that at least two regions contribute significantly to the infrared/optical/ultraviolet/

关键词： Galaxies

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Performance evaluation of the high-voltage CMOS active pixel sensor AstroPix for gamma-ray space telescopes

arXiv

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arXiv 2024年

作者： Suda, Yusuke Caputo, Regina Steinhebel, Amanda L. Striebig, Nicolas Jadhav, Manoj Fukazawa, Yasushi Hashizume, Masaki Kierans, Carolyn Leys, Richard Metcalfe, Jessica Negro, Michela Perić, Ivan Perkins, Jeremy S. Shin, Taylor Tajima, Hiroyasu Violette, Daniel Nakano, Norito Physics Program Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashihiroshima Hiroshima739-8526 Japan NASA Goddard Space Flight Center 8800 Greenbelt Rd GreenbeltMDMD 20771 United States 8800 Greenbelt Rd GreenbeltMDMD 20771 United States ASIC and Detector Laboratory Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 Karlsruhe Baden-WürttembergD-76344 Germany Argonne National Laboratory 9700 S. Cass Avenue LemontILIL 60439 United States Department of Physics and Astronomy Louisiana State University 202 Nicholson Hall Baton RougeLALA 70803 United States University of California Santa Cruz 1156 High Street Santa CruzCACA 95064 United States Institute for Space–Earth Environmental Research Nagoya University Furo-cho Chikusa-ku Aichi Nagoya464-8601 Japan Kobayashi-Maskawa Institute for the Origin of Particles and the Universe Nagoya University Furo-cho Chikusa-ku Aichi Nagoya464-8602 Japan

AstroPix is a novel monolithic high-voltage CMOS active pixel sensor proposed for next generation medium-energy gamma-ray observatories like the All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X). For AMEGO-X AstroPix must maintain a power consumption of less than 1.5 mW/cm2 while having a pixel pitch of up to 500 µm. We developed the second and third versions of AstroPix, namely AstroPix2 and AstroPix3. AstroPix2 and AstroPix3 exhibit power consumptions of 3.4 mW/cm2 and 4.1 mW/cm2, respectively. While AstroPix2 has a pixel pitch of 250 µm, AstroPix3 achieves the desired size for AMEGO-X with a pixel pitch of 500 µm. Performance evaluation of a single pixel in an AstroPix2 chip revealed a dynamic range from 13.9 keV to 59.5 keV, with the energy resolution meeting the AMEGO-X target value (60Co source. The chip was fully operational after irradiation although a decrease in gain by approximately 4% was observed. Copyright © 2024, The Authors. All rights reserved.

关键词： CMOS integrated circuits

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First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way

arXiv

引用

arXiv 2023年

作者： Akiyama, Kazunori Alberdi, Antxon Alef, Walter Algaba, Juan Carlos Anantua, Richard Asada, Keiichi Azulay, Rebecca Bach, Uwe Baczko, Anne-Kathrin Ball, David Baloković, Mislav Barrett, John Bauböck, Michi Benson, Bradford A. Bintley, Dan Blackburn, Lindy Blundell, Raymond Bouman, Katherine L. Bower, Geoffrey C. Boyce, Hope Bremer, Michael Brinkerink, Christiaan D. Brissenden, Roger Britzen, Silke Broderick, Avery E. Broguiere, Dominique Bronzwaer, Thomas Bustamante, Sandra Byun, Do-Young Carlstrom, John E. Ceccobello, Chiara Chael, Andrew Chan, Chi-Kwan Chatterjee, Koushik Chatterjee, Shami Chen, Ming-Tang Chen, Yongjun Cheng, Xiaopeng Cho, Ilje Christian, Pierre Conroy, Nicholas S. Conway, John E. Cordes, James M. Crawford, Thomas M. Crew, Geoffrey B. Cruz-Osorio, Alejandro Cui, Yuzhu Davelaar, Jordy De Laurentis, Mariafelicia Deane, Roger Dempsey, Jessica Desvignes, Gregory Dexter, Jason Dhruv, Vedant Doeleman, Sheperd S. Dougal, Sean Dzib, Sergio A. Eatough, Ralph P. Emami, Razieh Falcke, Heino Farah, Joseph Fish, Vincent L. Fomalont, Ed Ford, H. Alyson Fraga-Encinas, Raquel Freeman, William T. Friberg, Per Fromm, Christian M. Fuentes, Antonio Galison, Peter Gammie, Charles F. García, Roberto Gentaz, Olivier Georgiev, Boris Goddi, Ciriaco Gold, Roman Gómez-Ruiz, Arturo I. Gómez, José L. Gu, Minfeng Gurwell, Mark Hada, Kazuhiro Haggard, Daryl Haworth, Kari Hecht, Michael H. Hesper, Ronald Heumann, Dirk Ho, Luis C. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Huang, Lei Hughes, David H. Ikeda, Shiro Impellizzeri, C.M. Violette Inoue, Makoto Issaoun, Sara James, David J. Jannuzi, Buell T. Janssen, Michael Jeter, Britton Jiang, Wu Jiménez-Rosales, Alejandra Johnson, Michael D. Jorstad, Svetlana Joshi, Abhishek V. Jung, Taehyun Karami, Mansour Karuppusamy, Ramesh Kawashima, Tomohisa Keating, Garrett K. Kettenis, Mark Kim, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kino, Motoki Koay, Jun Yi Kocherlakota, Prashant Kofuji, Yutaro Koch, Patrick M. Koyama, Shoko Kramer, Carsten Kramer, Michael Krichbaum, Thomas P. Ku Massachusetts Institute of Technology Haystack Observatory 99 Millstone Road WestfordMA01886 United States National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Black Hole Initiative Harvard University 20 Garden Street CambridgeMA02138 United States Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n GranadaE-18008 Spain Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Department of Physics Faculty of Science Universiti Malaya Kuala Lumpur50603 Malaysia Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Department of Physics & Astronomy The University of Texas at San Antonio One UTSA Circle San AntonioTX78249 United States Institute of Astronomy and Astrophysics Academia Sinica 11F of Astronomy-Mathematics Building AS/NTU No. 1 Sec. 4 Roosevelt Rd Taipei10617 Taiwan Departament d'Astronomia i Astrofísica Universitat de València C. Dr. Moliner 50 Burjassot ValènciaE-46100 Spain Observatori Astronòmic Universitat de València C. Catedrático José Beltrán 2 Paterna ValènciaE-46980 Spain Steward Observatory Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Yale Center for Astronomy & Astrophysics Yale University 52 Hillhouse Avenue New HavenCT06511 United States Department of Physics University of Illinois 1110 West Green Street UrbanaIL61801 United States Fermi National Accelerator Laboratory MS209 P.O. Box 500 BataviaIL60510 United States Department of Astronomy and Astrophysics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States East Asian Observatory 660 N. A'ohoku Place HiloHI96720 United States 660 N. A'ohoku Place HiloHI96720 United States California Institute of Technology 1200 East California Boulevard PasadenaCA91125 United States Institute of Astronomy and Astrophysics Academia Sinica 645 N. A'ohoku Place HiloHI

We present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A∗), the Galactic center source associated with a supermassive black hole. These observations were conducted in 2017 using a global interferometric array of eight telescopes operating at a wavelength of λ = 1.3 mm. The EHT data resolve a compact emission region with intrahour variability. A variety of imaging and modeling analyses all support an image that is dominated by a bright, thick ring with a diameter of 51.8 ± 2.3 µas (68% credible interval). The ring has modest azimuthal brightness asymmetry and a comparatively dim interior. Using a large suite of numerical simulations, we demonstrate that the EHT images of Sgr A∗ are consistent with the expected appearance of a Kerr black hole with mass ∼4 × 106 M☉, which is inferred to exist at this location based on previous infrared observations of individual stellar orbits as well as maser proper motion studies. Our model comparisons disfavor scenarios where the black hole is viewed at high inclination (i > 50◦), as well as non-spinning black holes and those with retrograde accretion disks. Our results provide direct evidence for the presence of a supermassive black hole at the center of the Milky Way galaxy, and for the first time we connect the predictions from dynamical measurements of stellar orbits on scales of 103 − 105 gravitational radii to event horizon-scale images and variability. Furthermore, a comparison with the EHT results for the supermassive black hole M87∗ shows consistency with the predictions of general relativity spanning over three orders of magnitude in central mass. © 2023, CC BY.

关键词： Telescopes

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