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arXiv 2021年

作者： Chumak, Andrii V. Kabos, P. Wu, M. Abert, C. Adelmann, C. Adeyeye, A. Åkerman, J. Aliev, F.G. Anane, A. Awad, A. Back, C.H. Barman, A. Bauer, G.E.W. Becherer, M. Beginin, E.N. Bittencourt, V.A.S.V. Blanter, Y.M. Bortolotti, P. Boventer, I. Bozhko, D.A. Bunyaev, S.A. Carmiggelt, J.J. Cheenikundil, R.R. Ciubotaru, F. Cotofana, S. Csaba, G. Dobrovolskiy, O.V. Dubs, C. Elyasi, M. Fripp, K.G. Fulara, H. Golovchanskiy, I.A. Gonzalez-Ballestero, C. Graczyk, P. Grundler, D. Gruszecki, P. Gubbiotti, G. Guslienko, K. Haldar, A. Hamdioui, S. Hertel, R. Hillebrands, B. Hioki, T. Houshang, A. Hu, C.-M. Huebl, H. Huth, M. Iacocca, E. Jungfleisch, M.B. Kakazei, G.N. Khitun, A. Khymyn, R. Kikkawa, T. Kläui, M. Klein, O. Klos, J.W. Knauer, S. Koraltan, S. Kostylev, M. Krawczyk, M. Krivorotov, I.N. Kruglyak, V.V. Lachance-Quirion, D. Ladak, S. Lebrun, R. Li, Y. Lindner, M. Macêdo, R. Mayr, S. Melkov, G.A. Mieszczak, S. Nakamura, Y. Nembach, H.T. Nikitin, A.A. Nikitov, S.A. Novosad, V. Otalora, J.A. Otani, Y. Papp, A. Pigeau, B. Pirro, P. Porod, W. Porrati, F. Qin, H. Rana, B. Reimann, T. Riente, F. Romero-Isart, O. Ross, A. Sadovnikov, A.V. Safin, A.R. Saitoh, E. Schmidt, G. Schultheiss, H. Schultheiss, K. Serga, A.A. Sharma, S. Shaw, J.M. Suess, D. Surzhenko, O. Szulc, K. Taniguchi, T. Urbánek, M. Usami, K. Ustinov, A.B. van der Sar, T. van Dijken, S. Vasyuchka, V.I. Verba, R. Viola Kusminskiy, S. Wang, Q. Weides, M. Weiler, M. Wintz, S. Wolski, S.P. Zhang, X. Faculty of Physics University of Vienna Boltzmanngasse 5 ViennaA-1090 Austria National Institute of Standards and Technology BoulderCO80305 United States Department of Physics Colorado State University Fort CollinsCO80523 United States Research Platform MMM Mathematics-Magnetism-Materials University of Vienna Oskar-Morgenstern-Platz 1 Vienna1090 Austria Imec Leuven3001 Belgium Department of Physics Durham University South Road DurhamDH1 3LE United Kingdom Department of Physics University of Gothenburg Gothenburg412 96 Sweden Universidad Autónoma de Madrid Madrid28049 Spain Unité Mixte de Physique CNRS Thales Université Paris Saclay Palaiseau91767 France Department of Physics Technical University of Munich Garching85748 Germany Department of Condensed Matter Physics and Material Sciences S N Bose National Centre for Basic Sciences Salt Lake Kolkata700106 India Advanced Institute for Materials Research Tohoku University Sendai980-8577 Japan Zernike Institute for Advanced Materials University of Groningen Netherlands Department of Electrical and Computer Engineering Technical University of Munich Munich80333 Germany Laboratory of Magnetic Metamaterials Saratov State University Saratov410012 Russia Max Planck Institute for the Science of Light Erlangen91058 Germany Department of Quantum Nanoscience Kavli Institute of Nanoscience Delft University of Technology Delft2628 CJ Netherlands Department of Physics and Energy Science University of Colorado Colorado Springs Colorado SpringsCO80918 United States Departamento de Física e Astronomia Universidade do Porto Porto4169-007 Portugal Institut de Physique et Chimie des Matériaux de Strasbourg CNRS Université de Strasbourg StrasbourgF-67000 France Department of Quantum and Computer Engineering Delft University of Technology Delft2628 CD Netherlands Faculty for Information Technology and Bionics Pazmany Peter Catholic University Prater u. 50/A BudapestH-1083 Hungary INNOVENT e.V.

Magnonics is a field of science that addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operations in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors that covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with Boolean digital data, unconventional approaches like neuromorphic computing, and the progress towards magnon-based quantum computing. The article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of the current challenges and the outlook of the further development of the research directions. © 2021, CC BY.

关键词： Spin waves

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Image Description Method Based on Generative Adversarial Networks

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Ruan Jian Xue Bao/Journal of Software 2018年 29卷 30-43页

作者： Xue, Zi-Yu Guo, Pei-Yu Zhu, Xiao-Bin Zhang, Nai-Guang Information Technology Institute Academy of Broadcasting Science National Radio and Television Administration Beijing100866 China School of Computer and Information Engineering Beijing Technology and Business University Beijing100048 China

In recent years, deep learning has gained more and more attention in image description. The existing deep learning methods using CNNs to extract features and RNNs to fold into one sentence. Nevertheless, when dealing with complex images, the feature extraction is inaccurate. And the fixed mode of sentence generation model leads to inconsistent sentences. To solve this problem, this study proposes a method combine channel-wise attention model and GANs, named CACNN-GAN. The channel-wise attention mechanism is added to each conv-layer to extract features, compare with the COCO dataset, and select the top features to generate sentence. Using GANs to generate the sentences, which is generated by the game process between the generator and the discriminator. After that, we can get a sentence generator contains the varied syntax, smooth sentence, and rich vocabulary. Experiments on real datasets illustrates that CACNN-GAN can effectively describe images, and get higher accuracy compared with the state-of-art. © Copyright 2018, Institute of Software, the Chinese Academy of Sciences. All rights reserved.

关键词： Generative adversarial networks

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Density fluctuations associated with turbulence and waves: First observations by solar orbiter

arXiv

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arXiv 2021年

作者： Khotyaintsev, Yuri V. Graham, D.B. Vaivads, A. Steinvall, K. Edberg, N.J.T. Eriksson, A.I. Johansson, E.P.G. Sorriso-Valvo, L. Maksimovic, M. Bale, S.D. Chust, T. Krasnoselskikh, V. Kretzschmar, M. Lorfèvre, E. Plettemeier, D. Souček, J. Steller, M. Štverák, Š. Trávníček, P. Vecchio, A. Horbury, T.S. O’Brien, H. Evans, V. Angelini, V. Uppsala75121 Sweden Division of Space and Plasma Physics School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm11428 Sweden Space and Plasma Physics Department of Physics and Astronomy Uppsala University Uppsala75120 Sweden LESIA Observatoire de Paris Université PSL CNRS Sorbonne Université Univ. Paris Diderot Sorbonne Paris Cité 5 place Jules Janssen Meudon92195 France Space Sciences Laboratory University of California BerkeleyCA United States Physics Department University of California BerkeleyCA United States LPP CNRS Ecole Polytechnique Sorbonne Université Observatoire de Paris Université Paris-Saclay Palaiseau Paris France LPC2E CNRS 3A avenue de la Recherche Scientifique Orléans France Université d’Orléans Orléans France CNES 18 Avenue Edouard Belin Toulouse31400 France Technische Universität Dresden Helmholtz Str. 10 DresdenD-01187 Germany Institute of Atmospheric Physics of the Czech Academy of Sciences Prague Czech Republic Space Research Institute Austrian Academy of Sciences Graz Austria Astronomical Institute of the Czech Academy of Sciences Prague Czech Republic Radboud Radio Lab Department of Astrophysics Radboud University Nijmegen Netherlands Imperial College London South Kensington Campus LondonSW7 2AZ United Kingdom

Aims. The aim of this work is to demonstrate that the probe-to-spacecraft potential measured by RPW on Solar Orbiter can be used to derive the plasma (electron) density measurement, which both has a high temporal resolution and is of high accuracy. To investigate the physical nature of the solar wind turbulence and waves we analyze the density and magnetic field fluctuations around the proton cyclotron frequency observed by Solar Orbiter during the first perihelion encounter (∼0.5 AU away from the Sun). Methods. We use the plasma density based on measurements of the probe-to-spacecraft potential in combination with magnetic field measurements by MAG to study fields and density fluctuations in the solar wind. In particular, we use the polarization of the wave magnetic field, the phase between the compressible magnetic field and density fluctuations, and the compressibility ratio (the ratio of the normalized density fluctuations to the normalized compressible fluctuations of B) to characterize the observed waves and turbulence. Results. We find that the density fluctuations are 180◦ out-of-phase (anti-correlated) with the compressible component of magnetic fluctuations for intervals of turbulence, while they are in phase for the circular-polarized waves. We analyze in detail two specific events with simultaneous presence of left- and right-handed waves at different frequencies. We compare observed wave properties to a prediction of the three-fluid (electrons, protons and alphas) model. We find a limit on the observed wavenumbers, 10-6 6 m-1, which corresponds to wavelength 7 × 106 > λ > 106 m. We conclude that most likely both the left- and right-handed waves correspond to the low-wavenumber part (close to the cut-off at ΩcHe++) proton-band electromagnetic ion cyclotron (left-handed wave in the plasma frame confined to the frequency range ΩcHe++ cH+) waves propagating in the outwards and inwards directions respectively. The fact that both wave polarizations are observ

关键词： Solar wind

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First dust measurements with the solar orbiter radio and plasma wave instrument

arXiv

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arXiv 2021年

作者： Zaslavsky, A. Mann, I. Soucek, J. Czechowski, A. Pisa, D. Vaverka, J. Meyer-Vernet, N. Maksimovic, M. Lorfèvre, E. Issautier, K. Racković Babić, K. Bale, S.D. Morooka, M. Vecchio, A. Chust, T. Khotyaintsev, Y. Krasnoselskikh, V. Kretzschmar, M. Plettemeier, D. Steller, M. Štverák, S. Trávníček, P. Vaivads, A. Lesia Observatoire de Paris Université Psl Cnrs Sorbonne Université Université de Paris France Arctic University of Norway Tromsø Norway Institute of Atmospheric Physics of the Czech Academy of Sciences Prague Czech Republic Space Research Center Polish Academy of Sciences Warsaw Poland Faculty of Mathematics and Physics Charles University Prague Czech Republic Cnes 18 Avenue Edouard Belin Toulouse31400 France Department of Astronomy Faculty of Mathematics University of Belgrade Serbia Space Sciences Laboratory University of California BerkeleyCA United States Physics Department University of California BerkeleyCA United States Swedish Institute of Space Physics Uppsala Sweden Radboud Radio Lab Department of Astrophysics Radboud University Nijmegen Netherlands Lpp Cnrs Ecole Polytechnique Sorbonne Université Observatoire de Paris Université Paris-Saclay Palaiseau Paris France LPC2E Cnrs 3A avenue de la Recherche Scientifique Orléans France Université D'Orléans Orléans France Technische Universität Dresden Würzburger Str. 35 DresdenD-01187 Germany Space Research Institute Austrian Academy of Sciences Graz Austria Astronomical Institute of the Czech Academy of Sciences Prague Czech Republic Department of Space and Plasma Physics School of Electrical Engineering and Computer Science Royal Institute of Technology Stockholm Sweden

Context. Impacts of dust grains on spacecraft are known to produce typical impulsive signals in the voltage waveform recorded at the terminals of electric antennas. Such signals are, as could be expected, routinely detected by the Time Domain Sampler (TDS) system of the radio and Plasma Waves (RPW) instrument aboard Solar Orbiter. Aims. We investigate the capabilities of RPW in terms of interplanetary dust studies and present the first analysis of dust impacts recorded by this instrument. Our purpose is to characterize the dust population observed in terms of size, flux and velocity. Methods. We briefly discuss previously developed models of voltage pulses generation after a dust impact onto a spacecraft and present the relevant technical parameters for Solar Orbiter RPW as a dust detector. Then we present the statistical analysis of the dust impacts recorded by RPW/TDS from April 20th, 2020 to February 27th, 2021 between 0.5 AU and 1 AU. Results. The study of the dust impact rate along Solar Orbiter's orbit shows that the dust population studied presents a radial velocity component directed outward from the Sun, the order of magnitude of which can be roughly estimated as vr,dust≅ 50 km.s-1. This is consistent with the flux of impactors being dominated by β-meteoroids. We estimate the cumulative flux of these grains at 1 AU to be roughly Fβ≅ 8×10-5m-2s-1, for particles of radius r 100 nm. The power law index δ of the cumulative mass flux of the impactors is evaluated by two differents methods (direct observations of voltage pulses and indirect effect on the impact rate dependency on the impact speed). Both methods give a result δ ≅ 0.3 - 0.4. Conclusions. Solar Orbiter RPW proves to be a suitable instrument for interplanetary dust studies, and the dust detection algorithm implemented in the TDS subsystem an efficient tool for fluxes estimation. These first results are promising for the continuation of the mission, in particular for the in-situ study of the dust clou

关键词： Orbits

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A clock stabilization system for CHIME/FRB Outriggers

arXiv

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arXiv 2021年

作者： Mena-Parra, Juan Leung, C. Cary, S. Masui, K.W. Kaczmarek, J.F. Amiri, M. Bandura, K. Boyle, P.J. Cassanelli, T. Cliche, J.-F. Dobbs, M. Kaspi, V.M. Landecker, T.L. Lanman, A. Sievers, J.L. MIT Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology 77 Massachusetts Ave CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology 77 Massachusetts Ave CambridgeMA02139 United States Department of Astronomy Wellesley College 106 Central Street WellesleyMA02481 United States National Research Council Canada Herzberg Astronomy and Astrophysics Research Centre Dominion Radio Astrophysical Observatory PO Box 248 PentictonBCV2A 6J9 Canada Department of Physics and Astronomy University of British Columbia 6224 Agricultural Road VancouverBCV6T 1Z1 Canada Lane Department of Computer Science and Electrical Engineering 1220 Evansdale Drive PO Box 6109 MorgantownWV26506 United States Center for Gravitational Waves and Cosmology West Virginia University Chestnut Ridge Research Building MorgantownWV26505 United States Department of Physics McGill University 3600 rue University MontréalQCH3A 2T8 Canada McGill Space Institute McGill University 3550 rue University MontréalQCH3A 2A7 Canada Dunlap Institute for Astronomy & Astrophysics University of Toronto 50 St. George Street TorontoONM5S 3H4 Canada David A. Dunlap Department of Astronomy & Astrophysics University of Toronto 50 St. George Street TorontoONM5S 3H4 Canada Dominion Radio Astrophysical Observatory Herzberg Research Centre for Astronomy and Astrophysics National Research Council Canada PO Box 248 PentictonBCV2A 6J9 Canada Perimeter Institute for Theoretical Physics 31 Caroline Street N WaterlooONN25 2YL Canada School of Chemistry and Physics University of KwaZulu-Natal 238 Mazisi Kunene Rd Glenwood Durban4041 South Africa

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has emerged as the prime telescope for detecting fast radio bursts (FRBs). CHIME/FRB Outriggers will be a dedicated very-long-baseline interferometry (VLBI) instrument consisting of outrigger telescopes at continental baselines working with CHIME and its specialized real-time transient-search backend (CHIME/FRB) to detect and localize FRBs with 50 mas precision. In this paper we present a minimally invasive clock stabilization system that effectively transfers the CHIME digital backend reference clock from its original GPS-disciplined ovenized crystal oscillator to a passive hydrogen maser. This enables us to combine the long-term stability and absolute time tagging of the GPS clock with the short and intermediate-term stability of the maser to reduce the clock timing errors between VLBI calibration observations. We validate the system with VLBI-style observations of Cygnus A over a 400 m baseline between CHIME and the CHIME Pathfinder, demonstrating agreement between sky-based and maser-based timing measurements at the 30 ps rms level on timescales ranging from one minute to up to nine days, and meeting the stability requirements for CHIME/FRB Outriggers. In addition, we present an alternate reference clock solution for outrigger stations which lack the infrastructure to support a passive hydrogen maser. © 2021, CC BY.

关键词： Hydrogen

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Joint optimization of sensing period and transmission time for energy-efficient CRSNs 11

Joint optimization of sensing period and transmission time f...

引用

11th International Conference on Ubiquitous Information Management and Communication, IMCOM 2017

作者： Jin, Zilong Jinsung, Cho Kong, Fanhua Kim, Chang-Woo Na, Sangyeob School of Computer and Software Nanjing University of Information Science and Technology Nanjing China Cho Dept. of Computer Science and Engineering Kyung Hee University Yongin17104 Korea Republic of Dept. of Electronics and Radio Engineering Kyung Hee University Yongin17104 Korea Republic of Dept. of Computer Science Namseoul University Cheonan31020 Korea Republic of

ISBN: (纸本)9781450348881

Cognitive radio technology can enable secondary users (SUs) to occupy licensed bands in a non-interference way. SUs perform spectrum sensing to determine the presence of primary user (PU). Spectrum sensing period and transmission time are the critical parameters for the sensing performance and the secondary throughput, respectively. In this paper, a joint optimization of sensing period and transmission time is proposed for cognitive radio sensor network (CRSNs). The joint optimization model is established by taking the network energy efficiency and interference caused by SU's traffic into consideration. By using the optimization model, we try to figure out the optimal sensing period and transmission time which can guarantee the network energy efficiency and maximize the network throughput jointly. The performance of the proposed optimization model is evaluated through a set of simulations, and the existence of the optimal sensing period and transmission time is verified. © 2017 ACM.

关键词： Sensor networks

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Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: The hidden circumgalactic medium

arXiv

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arXiv 2024年

作者： Lee, Minju M. Schimek, Alice Cicone, Claudia Andreani, Paola Popping, Gergö Sommovigo, Laura Appleton, Philip N. Bischetti, Manuela Cantalupo, Sebastiano Chen, Chian-Chou Dannerbauer, Helmut De Breuck, Carlos Mascolo, Luca Di Emonts, Bjorn H.C. Hatziminaoglou, Evanthia Pensabene, Antonio Rizzo, Francesca Rybak, Matus Shen, Sijing Lundgren, Andreas Booth, Mark Klaassen, Pamela Mroczkowski, Tony Cordiner, Martin A. Johnstone, Doug van Kampen, Eelco Liu, Daizhong Maccarone, Thomas Saintonge, Amélie Smith, Matthew Thelen, Alexander E. Wedemeyer, Sven Denmark DTU-Space Technical University of Denmark Elektrovej 327 Kgs. LyngbyDK2800 Denmark Institute of Theoretical Astrophysics University of Oslo PO Box 1029 Blindern Oslo0315 Norway European Southern Observatory Karl-Schwarzschild-Straße 2 Garching bei München85748 Germany Center for Computational Astrophysics Flatiron Institute 162 5th Avenue New YorkNY10010 United States Caltech/IPAC MC 314-6 1200 E. California Blvd. PasadenaCA91125 United States Astronomy Unit Department of Physics University of Trieste via Tiepolo 11 Trieste34131 Italy INAF – Osservatorio Astronomico di Trieste via Tiepolo 11 Trieste34131 Italy Department of Physics University of Milan Bicocca Piazza della Scienza 3 MilanoI-20126 Italy No. 1 Sec. 4 Roosevelt Road Taipei10617 Taiwan Tenerife La LagunaE-38205 Spain Universidad de La Laguna Dpto. Astrofísica Tenerife La LagunaE-38206 Spain Laboratoire Lagrange Université Côte d’Azur Observatoire de la Côte d’Azur CNRS Blvd de l’Observatoire CS 34229 Nice06304 cedex 4 France IFPU Institute for Fundamental Physics of the Universe Via Beirut 2 Trieste34014 Italy National Radio Astronomy Observatory 520 Edgemont Road CharlottesvilleVA22903 United States Niels Bohr Institute University of Copenhagen Jagtvej 128 Copenhagen N2200 Denmark Leiden Observatory Leiden University PO Box 9513 Leiden2300-RA Netherlands Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technology Mekelweg 4 Delft2628 CD Netherlands SRON - Netherlands Institute for Space Research Niels Bohrweg 4 CA Leiden2333 Netherlands Aix Marseille Univ CNRS CNES LAM Marseille France UK Astronomy Technology Centre Royal Observatory Edinburgh Blackford Hill EdinburghEH9 3HJ United Kingdom Astrochemistry Laboratory Code 691 NASA Goddard Space Flight Center GreenbeltMD20771 United States NRC Herzberg Astronomy and Astrophysics 5071 West Saanich Rd VictoriaBCV9E 2E7 Canada Department of

Our knowledge of galaxy formation and evolution has incredibly progressed through multi-wavelength observational constraints of the interstellar medium (ISM) of galaxies at all cosmic epochs. However, little is known about the physical properties of the more diffuse and lower surface brightness reservoir of gas and dust that extends beyond ISM scales and fills dark matter haloes of galaxies up to their virial radii, the circumgalactic medium (CGM). New theoretical studies increasingly stress the relevance of the latter for understanding the feedback and feeding mechanisms that shape galaxies across cosmic times, whose cumulative effects leave clear imprints into the CGM. Recent studies are showing that a – so far unconstrained – fraction of the CGM mass may reside in the cold (T 4 K) molecular and atomic phase, especially in high-redshift dense environments. These gas phases, together with the warmer ionised phase, can be studied in galaxies from z ∼ 0 to z ∼ 10 through bright far-infrared and sub-millimeter emission lines such as [C II] 158µm, [O III] 88 µm, [C I] 609µm, [C I] 370µm, and the rotational transitions of CO. Imaging such hidden cold CGM can lead to a breakthrough in galaxy evolution studies but requires a new facility with the specifications of the proposed Atacama Large Aperture Submillimeter Telescope (AtLAST). In this paper, we use theoretical and empirical arguments to motivate future ambitious CGM observations with AtLAST and describe the technical requirements needed for the telescope and its instrumentation to perform such science. © 2024, CC BY.

关键词： Galaxies

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A survey on high-capacity OFDM-based passive optical networks

arXiv

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arXiv 2018年

作者： Ghanbarisabagh, Mohammad Vetharatnam, Gobi Giacoumidis, Elias Rouzegar, Hossein Mallouki, Nasreddine Department of Electrical Engineering Faculty of Electrical Engineering and Computer Sciences Islamic Azad University North Tehran Branch Hakimieh Tehran Iran Department of Electrical and Electronic Engineering Lee Kong Chian Faculty of Engineering and Science University Tunku Abdul Rahman Malaysia Dublin City University School of Electronic Engineering Radio and Optical Communications Lab Glasnevin 9 Dublin Ireland Department of Electrical and Computer Engineering Babol Noshirvani University of Technology Babol Iran Sys’comLab ENIT BP.37 Le Belvédère 1002Tunis Tunisia

The exponential growth of demand for high-speed internet and high bandwidth applications such as interactive entertainment in access networks mandates the requirement for higher optical signal speeds. On the other hand, since cost and energy efficiency should be concurrently preserved in access networks, passive optical networks (PONs) have emerged as a breakthrough solution. Currently, the 10 Gb/s (10GE-PON) standard which employs time division multiplexing is not sufficient to fulfill users’ requirements, and therefore, more advanced and spectrally efficient modulation formats are required. A potential solution is the implementation of hybrid wavelength division multiplexing (WDM) with orthogonal frequency-division multiplexing (OFDM), in which a specific wavelength and electronic subcarriers are assigned to each optical network unit according to users’ bandwidth requirements. This survey shows that future-proof PONs should be supported by an adaptively modulated WDM-OFDM architecture to maximize signal capacity and transmission-reach in PONs, while the employment of reflective semiconductor optical amplification and remodulation can potentially prevent the employment of an additional light source. Copyright © 2018, The Authors. All rights reserved.

关键词： Passive optical networks

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ALESS-JWST: Joint (sub-)kiloparsec JWST and ALMA imaging of z ∼ 3 submillimeter galaxies reveals heavily obscured bulge formation events

arXiv

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arXiv 2024年

作者： Hodge, Jacqueline A. da Cunha, Elisabete Kendrew, Sarah Li, Juno Smail, Ian Westoby, Bethany A. Nayak, Omnarayani Swinbank, Mark A. Chen, Chian-Chou Walter, Fabian van der Werf, Paul Cracraft, Misty Battisti, Andrew Brandt, Willian N. Rivera, Gabriela Calistro Chapman, Scott C. Cox, Pierre Dannerbauer, Helmut Decarli, Roberto Castillo, Marta Frias Greve, Thomas R. Knudsen, Kirsten K. Leslie, Sarah Menten, Karl M. Rybak, Matus Schinnerer, Eva Wardlow, Julie L. Weiss, Axel Leiden Observatory Leiden University P.O. Box 9513 Leiden2300 RA Netherlands International Centre for Radio Astronomy Research University of Western Australia 35 Stirling Hwy Crawley26WA 6009 Australia Australia ESA Office Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Centre for Extragalactic Astronomy Department of Physics Durham University South Road DurhamDH1 3LE United Kingdom NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD United States No. 1 Sec. 4 Roosevelt Road Taipei106216 Taiwan Max–Planck Institut für Astronomie Königstuhl 17 Heidelberg69117 Germany Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Research School of Astronomy and Astrophysics Australian National University Cotter Road Weston CreekACT2611 Australia Department of Astronomy and Astrophysics 525 Davey Lab The Pennsylvania State University University ParkPA16802 United States Institute for Gravitation and the Cosmos The Pennsylvania State University University ParkPA16802 United States Department of Physics 104 Davey Laboratory The Pennsylvania State University University ParkPA16802 United States Institute of Communications and Navigation Wessling Germany Karl-Schwarzschild-Straße 2 M¨unchen Garching85748 Germany Department of Physics and Atmospheric Science Dalhousie University 6310 Coburg Road HalifaxB3H 4R2 Canada National Research Council Herzberg Astronomy and Astrophysics 5071 West Saanich Road VictoriaV9E 2E7 Canada Department of Physics and Astronomy University of British Columbia 6225 Agricultural Road VancouverV6T 1Z1 Canada Eureka Scientific Inc OaklandCA94602 United States Sorbonne Université UPMC Université Paris 6 CNRS UMR 7095 Institut d’Astrophysique de Paris 98bis boulevard Arago Paris75014 France 39020 Spain INAF Osservatorio di Astrofisica e Scienza dello Spazio di Bologna via Gobetti 93/3 BolognaI-40129 Italy De

We present JWST NIRCam imaging targeting 13 z∼3 infrared-luminous (LIR ∼ 5×1012L) galaxies from the ALESS survey with uniquely deep, high-resolution (0.08′′–0.16′′) ALMA 870µm imaging. The 2.0-4.4µm (observed frame) NIRCam imaging reveals the rest-frame near-infrared stellar emission in these submillimeter-selected galaxies (SMGs) at the same (sub-)kpc resolution as the 870µm dust continuum. The newly revealed stellar morphologies show striking similarities with the dust continuum morphologies at 870µm, with the centers and position angles agreeing for most sources, clearly illustrating that the spatial offsets reported previously between the 870µm and HST morphologies were due to strong differential dust obscuration. The F444W sizes are 78±21% larger than those measured at 870µm, in contrast to recent results from hydrodynamical simulations that predict larger 870µm sizes. We report evidence for significant dust obscuration in F444W for the highest-redshift sources, emphasizing the importance of longer-wavelength MIRI imaging. The majority of the sources show evidence that they are undergoing mergers/interactions, including tidal tails/plumes—some of which are also detected at 870µm. We find a clear correlation between NIRCam colors and 870µm surface brightness on ∼1 kpc scales, indicating that the galaxies are primarily red due to dust—not stellar age—and we show that the dust structure on ∼kpc-scales is broadly similar to that in nearby galaxies. Finally, we find no strong stellar bars in the rest-frame near-infrared, suggesting the extended bar-like features seen at 870µm are highly obscured and/or gas-dominated structures that are likely early precursors to significant bulge growth. © 2024, CC BY.

关键词： Dust

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Whistler waves observed by Solar Orbiter / RPW between 0.5 AU and 1 AU

arXiv

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arXiv 2021年

作者： Kretzschmar, Matthieu Chust, T. Krasnoselskikh, V. Graham, D. Colomban, L. Maksimovic, M. Khotyaintsev, Yu V. Soucek, J. Steinvall, K. Santolík, O. Jannet, G. Brochot, J.-Y. Le Contel, O. Vecchio, A. Bonnin, X. Bale, S.D. Froment, C. Larosa, A. Bergerard-Timofeeva, M. Fergeau, P. Lorfevre, E. Plettemeier, D. Steller, M. Štverák, Š. Trávníček, P. Vaivads, A. Horbury, T.S. O’Brien, H. Evans, V. Angelini, V. Owen, C. Louarn, P. LPC2E UMR7328 CNRS University of Orléans 3A avenue de la recherche scientifique Orléans France LPP CNRS Ecole Polytechnique Sorbonne Université Observatoire de Paris Université Paris-Saclay Palaiseau Paris France Uppsala Sweden LESIA Observatoire de Paris Université PSL CNRS Sorbonne Université Université de Paris Meudon France Institute of Atmospheric Physics Czech Academy of Sciences Prague Czech Republic CNES 18 Avenue Edouard Belin Toulouse31400 France Technische Universität Dresden Würzburger Str. 35 DresdenD-01187 Germany Space Research Institute Austrian Academy of Sciences Graz Austria Astronomical Institute of the Czech Academy of Sciences Prague Czech Republic Radboud Radio Lab Department of Astrophysics Radboud University Nijmegen Netherlands Space Sciences Laboratory University of California BerkeleyCA United States Physics Department University of California CA United States Stellar Scientific BerkeleyCA United States Department of Space and Plasma Physics School of Electrical Engineering and Computer Science Royal Institute of Technology Stockholm Sweden Department of Physics Imperial College LondonSW7 2AZ United Kingdom Mullard Space Science Laboratory University College London Holmbury St. Mary Dorking SurreyRH5 6NT United Kingdom Institut de Recherche en Astrophysique et Planétologie 9 Avenue du Colonel ROCHE BP 4346 Toulouse Cedex 431028 France

Context. The solar wind evolution differs from a simple radial expansion and wave-particle interactions are supposed to be the major cause for the observed dynamics of the electron distribution function. In particular, whistler waves are thought to inhibit the electron heat flux and ensure the diffusion of the field aligned energetic electrons (Strahl) to replenish the halo population. Aims. The goal of our study is to detect and characterize the electromagnetic waves that can modify the electron distribution functions, with a special attention to whistler waves. Methods. We analyse in details the electric and magnetic field fluctuations observed by the Solar Orbiter spacecraft during its first orbit around the Sun between 0.5 and 1 AU. Using data of the Search Coil Magnetometer and electric antenna, both parts of the radio and Plasma Waves (RPW) instrumental suite, we detect the electromagnetic waves with frequencies above 3 Hz and determine the statistical distribution of their amplitudes, frequencies, polarization and k-vector as a function of distance. We also discuss relevant instrumental issues regarding the phase between the electric and magnetic measurements and the effective length of the electric antenna. Results. An overwhelming majority of the observed waves are right hand circularly polarized in the solar wind frame and identified as outward propagating and quasi parallel whistler waves. Their occurrence rate increases by a least a factor two from 1 AU to 0.5 AU. These results are consistent with the regulation of the heat flux by the whistler heat flux instability. Near 0.5 AU, whistler waves are found to be more field-aligned and to have smaller normalized frequency (f/ fce), larger amplitude, and larger bandwidth than at 1 AU. © 2021, CC BY-NC-ND.

关键词： Electromagnetic waves

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