检索结果-内蒙古大学图书馆

Correction: An electrodeposited superaerophobic nickel catalyst on pencil-drawn paper: a novel approach for highly efficient and stable hydrogen evolution

学校读者我要写书评

暂无评论

Inorganic Chemistry Frontiers 2024年第12期11卷 3654-3654页

作者： Qian Sun Xiaoyu Hao Tianyi Zhang Zelin Ma Kui Hu Ming Yang Xiaolei Huang Xuqing Liu State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical University Xi'an Shaanxi 710072 P. R. China Department of Chemistry University of Manchester Manchester UK Department of Applied Physics The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong SAR China Research Centre on Data Sciences & Artificial Intelligence The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong SAR China Institute of Material and Chemistry Ganjiang Innovation Academy Chinese Academy of Sciences Ganzhou China Shandong Laboratory of Yantai Advanced Materials and Green Manufacture Yantai China

Correction for ‘An electrodeposited superaerophobic nickel catalyst on pencil-drawn paper: a novel approach for highly efficient and stable hydrogen evolution’ by Qian Sun et al., Inorg. Chem. Front., 2024, https://...

Correction for ‘An electrodeposited superaerophobic nickel catalyst on pencil-drawn paper: a novel approach for highly efficient and stable hydrogen evolution’ by Qian Sun et al., Inorg. Chem. Front., 2024, https://***/10.1039/D4QI00101J.

关键词：

Exoplanet: Gradient-based probabilistic inference for exoplanet data & other astronomical time series

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Foreman-Mackey, Daniel Luger, Rodrigo Agol, Eric Barclay, Thomas Bouma, Luke G. Brandt, Timothy D. Czekala, Ian David, Trevor J. Dong, Jiayin Gilbert, Emily A. Gordon, Tyler A. Hedges, Christina Hey, Daniel R. Morris, Brett M. Price-Whelan, Adrian M. Savel, Arjun B. Center for Computational Astrophysics Flatiron Institute New YorkNY United States Virtual Planetary Laboratory University of Washington SeattleWA United States Department of Astronomy University of Washington SeattleWA United States Center for Space Sciences and Technology University of Maryland Baltimore County BaltimoreMD United States Department of Astrophysical Sciences Princeton University PrincetonNJ United States Department of Physics University of California Santa Barbara Santa BarbaraCA United States Department of Astronomy and Astrophysics Pennsylvania State University University ParkPA United States Center for Exoplanets and Habitable Worlds Pennsylvania State University University ParkPA United States Center for Astrostatistics Pennsylvania State University University ParkPA United States Institute for Computational and Data Sciences Pennsylvania State University University ParkPA United States Department of Astrophysics American Museum of Natural History New YorkNY United States Department of Astronomy and Astrophysics University of Chicago ChicagoIL United States Nasa Ames Research Center Moffett FieldCA United States Bay Area Environmental Research Institute Moffett FieldCA United States Sydney Institute for Astronomy School of Physics University of Sydney CamperdownNSW Australia Stellar Astrophysics Centre Department of Physics and Astronomy Aarhus University Aarhus Denmark Center for Space and Habitability University of Bern Bern Switzerland Department of Astronomy University of Maryland College ParkMD United States

exoplanet is a toolkit for probabilistic modeling of astronomical time series data, with a focus on observations of exoplanets, using PyMC3 (Salvatier et al., 2016). PyMC3 is a flexible and high-performance model-building language and inference engine that scales well to problems with a large number of parameters. exoplanet extends PyMC3's modeling language to support many of the custom functions and probability distributions required when fitting exoplanet datasets or other astronomical time series. While it has been used for other applications, such as the study of stellar variability (e.g., Gillen et al., 2020;Medina et al., 2020), the primary purpose of exoplanet is the characterization of exoplanets (e.g., Gilbert et al., 2020;Plavchan et al., 2020) or multiple-star systems (e.g., Czekala et al., 2021) using time-series photometry, astrometry, and/or radial velocity. In particular, the typical use case would be to use one or more of these datasets to place constraints on the physical and orbital parameters of the system, such as planet mass or orbital period, while simultaneously taking into account the effects of stellar variability. © 2021, CC BY.

关键词： Stars

GOODS-ALMA 2.0: Starbursts in the main sequence reveal compact star formation regulating galaxy evolution prequenching

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Gómez-Guijarro, Carlos Elbaz, D. Xiao, M. Kokorev, V.I. Magdis, G.E. Magnelli, B. Daddi, E. Valentino, F. Sargent, M.T. Dickinson, M. Béthermin, M. Franco, M. Pope, A. Kalita, B.S. Ciesla, L. Demarco, R. Inami, H. Rujopakarn, W. Shu, X. Wang, T. Zhou, L. Alexander, D.M. Bournaud, F. Chary, R. Ferguson, H.C. Finkelstein, S.L. Giavalisco, M. Iono, D. Juneau, S. Kartaltepe, J.S. Lagache, G. Le Floc'h, E. Leiton, R. Leroy, L. Lin, L. Motohara, K. Mullaney, J. Okumura, K. Pannella, M. Papovich, C. Treister, E. AIM CEA CNRS Université Paris-Saclay Université Paris Diderot Sorbonne Paris Cité Gif-sur-Yvette F-91191 France School of Astronomy and Space Science Nanjing University Nanjing210093 China Denmark Niels Bohr Institute University of Copenhagen Jagtvej 128 Copenhagen N DK-2200 Denmark DTU-Space Technical University of Denmark Elektrovej 327 Kgs. Lyngby DK-2800 Denmark Astronomy Centre Department of Physics and Astronomy University of Sussex BrightonBN1 9QH United Kingdom Hallerstrasse 6 BernCH-3012 Switzerland Community Science and Data Center NSF's NOIRLab 950 N. Cherry Ave. TucsonAZ85719 United States Aix Marseille Université CNRS LAM Laboratoire d'Astrophysique de Marseille Marseille France Centre for Astrophysics Research University of Hertfordshire HatfieldAL10 9AB United Kingdom Astronomy Department University of Massachusetts AmherstMA01003 United States Departamento de Astronomía Facultad de Ciencias Fsicas y Matemáticas Universidad de Concepción Concepción Chile Hiroshima Astrophysical Science Center Hiroshima University 1-3-1 Kagamiyama Hiroshima Higashi-Hiroshima 739-8526 Japan Department of Physics Faculty of Science Chulalongkorn University 254 Phayathai Road Pathumwan Bangkok10330 Thailand Don Kaeo Mae Rim Chiang Mai50180 Thailand UTIAS The University of Tokyo Chiba Kashiwa277-8583 Japan Department of Physics Anhui Normal University Anhui Wuhu241000 China Key Laboratory of Modern Astronomy and Astrophysics Nanjing University Ministry of Education Nanjing210093 China Centre for Extragalactic Astronomy Department of Physics Durham University DurhamDH1 3LE United Kingdom Infrared Processing and Analysis Center MS314-6 California Institute of Technology PasadenaCA91125 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Department of Astronomy The University of Texas at Austin AustinTX78712 United States National Astronomical Observatory of Jap

Compact star formation appears to be generally common in dusty star-forming galaxies (SFGs). However, its role in the framework set by the scaling relations in galaxy evolution remains to be understood. In this work we follow up on the galaxy sample from the GOODS-ALMA 2.0 survey, an ALMA blind survey at 1.1 mm covering a continuous area of 72.42 arcmin2 using two array configurations. We derived physical properties, such as star formation rates, gas fractions, depletion timescales, and dust temperatures for the galaxy sample built from the survey. There exists a subset of galaxies that exhibit starburst-like short depletion timescales, but they are located within the scatter of the so-called main sequence of SFGs. These are dubbed starbursts in the main sequence and display the most compact star formation and they are characterized by the shortest depletion timescales, lowest gas fractions, and highest dust temperatures of the galaxy sample, compared to typical SFGs at the same stellar mass and redshift. They are also very massive, accounting for ∼ 60% of the most massive galaxies in the sample (log(M∗/M ) > 11.0). We find trends between the areas of the ongoing star formation regions and the derived physical properties for the sample, unveiling the role of compact star formation as a physical driver of these properties. Starbursts in the main sequence appear to be the extreme cases of these trends. We discuss possible scenarios of galaxy evolution to explain the results drawn from our galaxy sample. Our findings suggest that the star formation rate is sustained in SFGs by gas and star formation compression, keeping them within the main sequence even when their gas fractions are low and they are presumably on the way to quiescence. Copyright © 2022, The Authors. All rights reserved.

关键词： Galaxies

Evaluation of planar silicon pixel sensors with the RD53A readout chip for the Phase-2 Upgrade of the CMS Inner Tracker

学校读者我要写书评

暂无评论

Journal of Instrumentation 2023年第11期18卷 P11015页

作者： Adam, W. Bergauer, T. Damanakis, K. Dragicevic, M. Frühwirth, R. Steininger, H. Beaumont, W. Darwish, M.R. Janssen, T. Rejeb Sfar, H. Van Mechelen, P. Breugelmans, N. Delcourt, M. De Moor, A. D’Hondt, J. Heyen, F. Lowette, S. Makarenko, I. Muller, D. Sahasransu, A.R. Vannerom, D. Van Putte, S. Allard, Y. Clerbaux, B. Dansana, S. De Lentdecker, G. Evard, H. Favart, L. Hohov, D. Khalilzadeh, A. Lee, K. Mahdavikhorrami, M. Malara, A. Paredes, S. Postiau, N. Robert, F. Thomas, L. Vanden Bemden, M. Vanlaer, P. Yang, Y. Benecke, A. Bruno, G. Bury, F. Caputo, C. De Favereau, J. Delaere, C. Donertas, I.S. Giammanco, A. Jaffel, K. Jain, S. Lemaitre, V. Mondal, K. Szilasi, N. Tran, T.T. Wertz, S. Brigljević, V. Chitroda, B. Ferenček, D. Mishra, S. Starodumov, A. Šuša, T. Brücken, E. Lampén, T. Martikainen, L. Tuominen, E. Karadzhinova-Ferrer, A. Luukka, P. Petrow, H. Tuuva, T. Agram, J.-L. Andrea, J. Apparu, D. Bloch, D. Bonnin, C. Brom, J.-M. Chabert, E. Charles, L. Collard, C. Dangelser, E. Falke, S. Goerlach, U. Gross, L. Haas, C. Krauth, M. Ollivier-Henry, N. Baulieu, G. Bonnevaux, A. Boudoul, G. Caponetto, L. Chanon, N. Contardo, D. Dupasquier, T. Galbit, G. Marchisone, M. Mirabito, L. Nodari, B. Schibler, E. Schirra, F. Vander Donckt, M. Viret, S. Botta, V. Ebisch, C. Feld, L. Karpinski, W. Klein, K. Lipinski, M. Louis, D. Meuser, D. Özen, I. Pauls, A. Pierschel, G. Röwert, N. Teroerde, M. Wlochal, M. Dziwok, C. Fluegge, G. Pooth, O. Stahl, A. Ziemons, T. Agah, A. Bhattacharya, S. Blekman, F. Campbell, A. Cardini, A. Cheng, C. Consuegra Rodriguez, S. Eckerlin, G. Eckstein, D. Gallo, E. Guthoff, M. Kleinwort, C. Mankel, R. Maser, H. Muhl, C. Mussgiller, A. Nürnberg, A. Otarid, Y. Perez Adan, D. Petersen, H. Pitzl, D. Rastorguev, D. Reichelt, O. Schütze, P. Sreelatha Pramod, L. Stever, R. Velyka, A. Ventura Barroso, A. Walsh, R. Zuber, A. Albrecht, A. Antonello, M. Biskop, H. Buhmann, P. Connor, P. Feindt, F. Garutti, E. Institut für Hochenergiephysik Wien Austria Universiteit Antwerpen Antwerpen Belgium Vrije Universiteit Brussel Brussel Belgium Université Libre de Bruxelles Bruxelles Belgium Université Catholique de Louvain Louvain-la-Neuve Belgium Institut Ruđer Bošković Zagreb Croatia Department of Physics University of Helsinki Helsinki Finland Helsinki Institute of Physics Helsinki Finland Lappeenranta-Lahti University of Technology Lappeenranta Finland Université de Strasbourg CNRS IPHC UMR 7178 Strasbourg France Université de Lyon Université Claude Bernard Lyon 1 CNRS IN2P3 IP2I Lyon UMR 5822 Villeurbanne France RWTH Aachen University I. Physikalisches Institut Aachen Germany RWTH Aachen University III. Physikalisches Institut B Aachen Germany Deutsches Elektronen-Synchrotron Hamburg Germany University of Hamburg Hamburg Germany Institut für Experimentelle Teilchenphysik KIT Karlsruhe Germany NCSR Demokritos Aghia Paraskevi Greece Wigner Research Centre for Physics Budapest Hungary National Institute of Science Education and Research HBNI Bhubaneswar India University of Delhi Delhi India Saha Institute of Nuclear Physics HBNI Kolkata India Indian Institute of Technology Madras Madras India INFN Sezione di Bari Bari Italy Università di Bari Bari Italy Politecnico di Bari Bari Italy INFN Sezione di Catania Catania Italy Università di Catania Catania Italy INFN Sezione di Firenze Firenze Italy Università di Firenze Firenze Italy INFN Sezione di Genova Genova Italy INFN Sezione di Milano-Bicocca Milano Italy Università di Milano-Bicocca Milano Italy INFN Sezione di Padova Padova Italy Università di Padova Padova Italy INFN Sezione di Pavia Pavia Italy Università di Bergamo Pavia Italy Bergamo Università di Pavia Pavia Italy INFN Sezione di Perugia Perugia Italy Università di Perugia Perugia Italy CNR-IOM Perugia Perugia Italy INFN Sezione di Pisa Siena Italy Università di Pisa Siena Italy Scuola Normale Superiore di Pisa Sien

The Large Hadron Collider at CERN will undergo an upgrade in order to increase its luminosity to 7.5 × 1034 cm-2s-1. The increased luminosity during this High-Luminosity running phase, starting around 2029, means a higher rate of proton-proton interactions, hence a larger ionizing dose and particle fluence for the detectors. The current tracking system of the CMS experiment will be fully replaced in order to cope with the new operating conditions. Prototype planar pixel sensors for the CMS Inner Tracker with square 50 μm × 50 μm and rectangular 100 μm × 25 μm pixels read out by the RD53A chip were characterized in the lab and at the DESY-II testbeam facility in order to identify designs that meet the requirements of CMS during the High-Luminosity running phase. A spatial resolution of approximately 3.4 μm (2 μm) is obtained using the modules with 50 μm×50 μm (100 μm × 25 μm) pixels at the optimal angle of incidence before irradiation. After irradiation to a 1MeV neutron equivalent fluence of Φeq = 5.3 × 1015 cm-2, a resolution of 9.4 μm is achieved at a bias voltage of 800V using a module with 50 μm × 50 μm pixel size. All modules retain a hit efficiency in excess of 99% after irradiation to fluences up to 2.1 × 1016 cm-2. Further studies of the electrical properties of the modules, especially crosstalk, are also presented in this paper. © 2023 institute of physics Publishing. All rights reserved.

关键词： Pixels

RUBIES Reveals a Massive Quiescent Galaxy at z=7.3

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Weibel, Andrea de Graaff, Anna Setton, David J. Miller, Tim B. Oesch, Pascal A. Brammer, Gabriel Lagos, Claudia D.P. Whitaker, Katherine E. Williams, Christina C. Baggen, Josephine F.W. Bezanson, Rachel Boogaard, Leindert A. Cleri, Nikko J. Greene, Jenny E. Hirschmann, Michaela Hviding, Raphael E. Kuruvanthodi, Adarsh Labbé, Ivo Leja, Joel Maseda, Michael V. Matthee, Jorryt McConachie, Ian Naidu, Rohan P. Roberts-Borsani, Guido Schaerer, Daniel Suess, Katherine A. Valentino, Francesco van Dokkum, Pieter Wang, Bingjie Department of Astronomy University of Geneva Chemin Pegasi 51 Versoix1290 Switzerland Max-Planck-Institut für Astronomie Königstuhl 17 HeidelbergD-69117 Germany Department of Astrophysical Sciences Princeton University 4 Ivy Lane PrincetonNJ08544 United States Northwestern University 1800 Sherman Ave EvanstonIL60201 United States Denmark Niels Bohr Institute University of Copenhagen Jagtvej 128 København NDK-2200 Denmark M468 University of Western Australia 35 Stirling Hwy CrawleyWA6009 Australia Australia Department of Astronomy University of Massachusetts AmherstMA01003 United States NSF’s National Optical-Infrared Astronomy Research Laboratory 950 North Cherry Avenue TucsonAZ85719 United States Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721 United States Department of Astronomy Yale University New HavenCT06511 United States Department of Physics and Astronomy PITT PACC University of Pittsburgh PittsburghPA15260 United States Leiden Observatory Leiden University PO Box 9513 LeidenNL-2300 RA Netherlands Department of Astronomy & Astrophysics The Pennsylvania State University University ParkPA16802 United States Institute for Computational & Data Sciences The Pennsylvania State University University ParkPA16802 United States Institute for Gravitation and the Cosmos The Pennsylvania State University University ParkPA16802 United States Institute of Physics Laboratory for galaxy evolution EPFL Observatory of Sauverny Chemin Pegasi 51 Versoix1290 Switzerland Centre for Astrophysics and Supercomputing Swinburne University of Technology MelbourneVIC3122 Australia Department of Astronomy University of Wisconsin-Madison 475 N. Charter St. MadisonWI53706 United States Am Campus 1 Klosterneuburg3400 Austria MIT Kavli Institute for Astrophysics and Space Research 77 Massachusetts Ave. CambridgeMA02139 United States CNRS IRAP 14 Avenue E. Belin Toulouse31400 France Departmen

We report the spectroscopic discovery of a massive quiescent galaxy at zspec = 7.29 ± 0.01, just ∼ 700 Myr after the Big Bang. RUBIES-UDS-QG-z7 was selected from public JWST/NIRCam and MIRI imaging from the PRIMER survey and observed with JWST/NIRSpec as part of RUBIES. The NIRSpec/PRISM spectrum reveals one of the strongest Balmer breaks observed thus far at z > 6, no emission lines, but tentative Balmer and Ca absorption features, as well as a Lyman break. Simultaneous modeling of the NIRSpec/PRISM spectrum and NIRCam and MIRI photometry (spanning 0.9−18 µm) shows that the galaxy formed a stellar mass of log(M∗/M☉) = 10.23+0.04−0.04 before z ∼ 8, and ceased forming stars 50−100 Myr prior to the time of observation, resulting in log(sSFR/Gyr−1) +33−24 pc, which implies a high stellar mass surface density within the effective radius of log(Σ∗,e/M☉ kpc−2) = 10.85+0.11−0.12 comparable to the highest densities measured in quiescent galaxies at z ∼ 2 − 5. The 3D stellar mass density profile of RUBIES-UDS-QG-z7 is remarkably similar to the central densities of local massive ellipticals, suggesting that at least some of their cores may have already been in place at z > 7. The discovery of RUBIES-UDS-QG-z7 has strong implications for galaxy formation models: the estimated number density of quiescent galaxies at z ∼ 7 is > 100× larger than predicted from any model to date, indicating that quiescent galaxies have formed earlier than previously expected. © 2024, CC BY.

关键词： Galaxies

Common explanation of the behavior of some e+e− annihilation processes around s=1.9 GeV

学校读者我要写书评

暂无评论

Physical Review D 2018年第11期98卷 113011-113011页

作者： Peter Lichard Institute of Physics and Research Centre for Computational Physics and Data Processing Silesian University in Opava 746 01 Opava Czech Republic and Institute of Experimental and Applied Physics Czech Technical University in Prague 128 00 Prague Czech Republic

We show that the behavior of the excitation curves of some e+e− annihilation processes close to the nucleon-antinucleon threshold can be explained either by the ρ(1900) resonance itself or by its interference with other resonances. Besides the six-pion annihilation and the e+e−→K+K−π+π− and e+e−→ϕπ0 processes, we also analyze the final states ηπ+π−, K+K−π+π−π0, and K+K−π0π0, the behavior of which around 1.9 GeV has not yet attracted attention. Analysis of the data on the e+e−→pp¯ and e+e−→nn¯ reactions clearly shows that the ρ(1900) resides above the nn¯ threshold.

关键词： Particle interactions

A new approximation of photon geodesics in Schwarzschild spacetime

学校读者我要写书评

暂无评论

arXiv 2019年

作者： la Placa, Riccardo Bakala, Pavel Stella, Luigi Falanga, Maurizio INAF - Osservatorio Astronomico di Roma Monte Porzio Catone Italy Research Centre for Computational Physics and Data Processing Silesian University in Opava Czech Republic M. R. Štefánik Observatory and Planetarium Hlohovec Slovakia Bern Switzerland International Space Science Institute Beijing China

Deep ASKAP EMU Survey of the GAMA23 field: Properties of radio sources

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Uygun, Gulay Gurkan Prandoni, I. O'Brien, A. Raja, W. Marchetti, L. Vaccari, M. Driver, S. Taylor, E. Franzen, T. Brown, M.J.I. Shabala, S. Andernach, H. Hopkins, A.M. Norris, R.P. Leahy, D. Bilicki, M. Farajollahi, H. Galvin, T. Heald, G. Koribalski, B.S. An, T. Warhurst, K. Thüringer Landessternwarte Sternwarte 5 TautenburgD-07778 Germany CSIRO Space and Astronomy ATNF PO Box 1130 BentleyWA6102 Australia INAF-IRA Via P. Gobetti 101 BolognaI-40129 Italy Department of Physics University of Wisconsin-Milwaukee P.O. Box 413 MilwaukeeWI53201 United States CSIRO Space and Astronomy ATNF P.O. Box 76 EppingNSW1710 Australia Department of Astronomy University of Cape Town Rondebosch Cape Town7701 South Africa Inter-University Institute for Data Intensive Astronomy Department of Astronomy University of Cape Town Rondebosch Cape Town7701 South Africa International Centre for Radio Astronomy Research University of Western Australia Perth Australia Centre for Astrophysics and Supercomputing Swinburne University of Technology Hawthorn3122 Australia ASTRON: the Netherlands Institute for Radio Astronomy PO Box 2 Dwingeloo7990 AA Netherlands School of Physics and Astronomy Monash University ClaytonVIC3800 Australia School of Natural Sciences University of Tasmania Private Bag 37 HobartTAS7001 Australia Depto. de Astronomía DCNE Universidad de Guanajuato Callejón. de Jalisco s/n GuanajuatoCP 36023 Mexico Australian Astronomical Optics Macquarie University 105 Delhi Rd North RydeNSW2113 Australia Western Sydney University Locked Bag 1797 PenrithNSW2751 Australia Dept. Physics and Astronomy University of Calgary CalgaryABT2N 1N4 Canada Center for Theoretical Physics Polish Academy of Sciences al. Lotników 32/46 Warsaw02-668 Poland International Centre for Radio Astronomy Research Curtin University 1 Turner Avenue BentleyWA6102 Australia Shanghai Astronomical Observatory Chinese Academy of Sciences Nandan road 80 Shanghai200030 China Key Laboratory of Cognitive Radio and Information Processing Guilin University of Electronic Technology Guilin541004 China

We present the Australian Square Kilometre Array Pathfinder (ASKAP) observations of the Galaxy and Mass Assembly (GAMA)23h field. The survey was carried out at 887.5 MHz and covers a ∼83 square degree field. We imaged the calibrated visibility data, taken as part of the Evolutionary Mapping of Universe (EMU) Early Science Programme, using the latest version of the ASKAPSoft pipeline. The final mosaic has an angular resolution of 10 arcsec and a central rms noise of around 38 μJy beam−1. The derived radio source catalogue has 39812 entries above a peak flux density threshold of 5σ. We searched for the radio source host galaxy counterparts using the GAMA spectroscopic (with an i-band magnitude limit of 19.2 mag) and multi-wavelength catalogues that are available as part of the collaboration. We identified hosts with GAMA spectroscopic redshifts for 5934 radio sources. We describe the data reduction, imaging, and source identification process, and present the source counts. Thanks to the wide area covered by our survey, we obtain very robust counts down to 0.2 mJy. ASKAP's exceptional survey speed, providing efficient, sensitive and high resolution mapping of large regions of the sky in conjunction with the multi-wavelength data available for the GAMA23 field, allowed us to discover 63 giant radio galaxies. The data presented here demonstrate the excellent capabilities of ASKAP in the pre-SKA era. Copyright © 2022, The Authors. All rights reserved.

关键词： Galaxies

Evidence for X-ray emission in excess to the jet afterglow decay 3.5 yrs after the binary neutron star merger GW 170817: A new emission component

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Hajela, Aprajita Margutti, R. Bright, J.S. Alexander, K.D. Metzger, B.D. Nedora, V. Kathirgamaraju, A. Margalit, B. Radice, D. Guidorzi, C. Berger, E. Macfadyen, A. Giannios, D. Chornock, R. Heywood, I. Sironi, L. Gottlieb, O. Coppejans, D. Laskar, T. Cendes, Y. Barniol Duran, R. Eftekhari, T. Fong, W. McDowell, A. Nicholl, M. Xie, X. Zrake, J. Bernuzzi, S. Broekgaarden, F.S. Kilpatrick, C.D. Terreran, G. Villar, V.A. Blanchard, P.K. Gomez, S. Hosseinzadeh, G. Matthews, D.J. Rastinejad, J.C. Center for Interdisciplinary Exploration and Research in Astrophysics Department of Physics and Astronomy Northwestern University 2145 Sheridan Road Evanston IL60208-3112 United States Department of Astronomy University of California BerkeleyCA94720-3411 United States Department of Physics Columbia University New YorkNY10027 United States Center for Computational Astrophysics Flatiron Institute 162 W. 5th Avenue New YorkNY10011 United States Max Planck Institute for Gravitational Physics Albert Einstein Institute Am Mühlenberg 1 Potsdam14476 Germany Institute for Physics and Astronomy University of Potsdam Potsdam14476 Germany Division of Physics Mathematics and Astronomy California Institute of Technology PasadenaCA91125 United States Astronomy Department and Theoretical Astrophysics Center University of California Berkeley BerkeleyCA94720 United States Institute for Gravitation and the Cosmos The Pennsylvania State University University ParkPA16802 United States Department of Physics The Pennsylvania State University University ParkPA16802 United States Department of Astronomy & Astrophysics The Pennsylvania State University University ParkPA16802 United States Department of Physics and Earth Science University of Ferrara via Saragat 1 FerraraI-44122 Italy INFN - Sezione di Ferrara via Saragat 1 FerraraI-44122 Italy INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna Via Piero Gobetti 101 BolognaI-40129 Italy Center for Astrophysics Harvard & Smithsonian 60 Garden St. CambridgeMA02138 United States Center for Cosmology and Particle Physics Physics Department New York University New YorkNY10003 United States Department of Physics and Astronomy Purdue University West LafayetteIN47907 United States Department of Physics University of Oxford Keble Road OxfordOX1 3RH United Kingdom Department of Physics and Electronics Rhodes University PO Box 94 Makhanda 6140 South Africa South African Radio Astronomy

For the first ∼ 3 years after the binary neutron star merger event GW 170817 the radio and X-ray radiation has been dominated by emission from a structured relativistic off-axis jet propagating into a low-density medium with n −3. We report on observational evidence for an excess of X-ray emission at δt > 900 days after the merger. With Lx ≈ 5 × 1038 erg s−1 at 1234 days, the recently detected X-ray emission represents a ≥ 3.2 σ (Gaussian equivalent) deviation from the universal post jet-break model that best fits the multi-wavelength afterglow at earlier times. In the context of JetFit afterglow models, current data represent a departure with statistical significance ≥ 3.1 σ, depending on the fireball collimation, with the most realistic models showing excesses at the level of ≥ 3.7 σ. A lack of detectable 3 GHz radio emission suggests a harder broad-band spectrum than the jet afterglow. These properties are consistent with the emergence of a new emission component such as synchrotron radiation from a mildly relativistic shock generated by the expanding merger ejecta, i.e. a kilonova afterglow. In this context, we present a set of ab-initio numerical-relativity BNS merger simulations that show that an X-ray excess supports the presence of a high-velocity tail in the merger ejecta, and argues against the prompt collapse of the merger remnant into a black hole. Radiation from accretion processes on the compact-object remnant represents a viable alternative. Neither a kilonova afterglow nor accretion-powered emission have been observed before, as detections of BNS mergers at this phase of evolution are unprecedented. Copyright © 2021, The Authors. All rights reserved.

关键词： Merging