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12 results on '"ALFVENIC TURBULENCE"'

1. Gyrofluid simulations of turbulence and reconnection in space plasmas

Author

T. Passot, S.S. Cerri, C. Granier, D. Laveder, P.L. Sulem, and E. Tassi

Subjects
Collisionless plasmas, Alfvenic turbulence, Magnetic reconnection, Gyrofluids, Plasma physics. Ionized gases, QC717.6-718.8, Science
Abstract

A Hamiltonian two-field gyrofluid model is used to investigate the dynamics of an electron-ion collisionless plasma subject to a strong ambient magnetic field, within a spectral range extending from the magnetohydrodynamic (MHD) scales to the electron skin depth. This model isolates Alfvén, Kinetic Alfvén and Inertial Kinetic Alfvén waves that play a central role in space plasmas, and extends standard reduced fluid models to broader ranges of the plasma parameters. Recent numerical results are reviewed, including (i) the reconnection-mediated MHD turbulence developing from the collision of counter-propagating Alfvén wave packets, (ii) the specific features of the cascade dynamics in strongly imbalanced turbulence, including a possible link between the existence of a spectral transition range and the presence of co-propagating wave interactions at sub-ion scales, for which new simulations are reported, (iii) the influence of the ion-to-electron temperature ratio in two-dimensional collisionless magnetic reconnection. The role of electron finite Larmor radius corrections is pointed out and the extension of the present model to a four-field gyrofluid model is discussed. Such an extended model accurately describes electron finite Larmor radius effects at small or moderate values of the electron beta parameter, and also retains the coupling to slow magnetosonic waves.

Published
2024
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2. Formation of the small-scale structure of auroral electron precipitations.

Author

Kropotkin, A.P.

Subjects
*AURORAL electrons, *ELECTRON precipitation, *ELECTRIC fields, *MAGNETOSPHERE, *SMALL scale system
Abstract

This paper is aimed at physical causes of the small-scale transverse structure in the flows of auroral electrons, generating the corresponding small-scale structure of discrete auroras. The parallel electric field existing in the lower part of the auroral magnetosphere, in the auroral cavity region, in the presence of a strong upward field-aligned current, accelerates magnetospheric electrons to energies of ∼ 1 − 10 keV. The flow of these particles while maintaining the high density of the field-aligned current, produces a current-driven instability, which generates Alfvénic turbulence at short perpendicular wavelengths ≤ 1 km. These short-wavelength inertial Alfvén disturbances possess a nonzero parallell electric field, which modulates the electron flow velocity. The modulation occurring at high altitudes ≥ 10 4 km leads to a nonlinear effect of formation of strong density peaks at low altitudes of electron precipitation. The transverse, horizontal scales of the corresponding electron flow structure coincide with the small scales of the Alfvénic turbulence; and this structuring leads to non-uniformities in the auroral luminosity on the same scales, i.e., to small-scale structure of discrete auroras. [ABSTRACT FROM AUTHOR]

Published
2016
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3. Seasonal asymmetry in the broadband ELF electric fields observed by the FAST satellite.

Author

Golovchanskaya, I.V., Kozelov, B.V., and Despirak, I.V.

Subjects
*ELF electromagnetic fields, *ELECTRIC fields, *TURBULENCE, *IONOSPHERE, *WINTER, *COMPARATIVE studies
Abstract

Abstract: Physical mechanism of the broadband ELF (BB ELF) turbulence observed in the topside ionosphere is not fully understood as yet. One feature that could, to a certain extent, shed light on its physics is a seasonal variation in the BB ELF electric fields at frequencies up to several hundred Hz (or higher) in the spacecraft frame. Specifically, the electric fields are several times enhanced in winter season compared to summer season. Such seasonal asymmetry was first reported by Heppner et al. (1993) for the AC electric fields measured by the Dynamics Explorer 2 (DE-2) satellite at altitudes from 300km to 900km. Here we demonstrate this effect by electric field observations of the FAST satellite (altitudes up to 4000km) with a sample rate of 512s−1 and discuss its implications for the involved generation mechanism of the BB ELF fields. [Copyright &y& Elsevier]

Published
2013
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4. Relaxed states of Alfve´nic turbulence

Author

Krishan, V. and Nocera, L.

Subjects
*TURBULENCE, *ENERGY dissipation, *MATHEMATICAL invariants
Abstract

The relaxed states of Alfve´nic turbulence, represented through the derivative nonlinear Schro¨dinger equation, are investigated by invoking the differential dissipation of the first three invariants and by the inverse energy cascade during four-wave interactions. We conclude that Alfve´nic turbulence relaxes to a state with soliton type structures which can become the ‘constant &z.sfnc;b&z.sfnc;’ (magnetic field) force-free state. [Copyright &y& Elsevier]

Published
2003
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5. Nature of kinetic scale turbulence in the Earth's magnetosheath

Author

Chen, CHK, Boldyrev, S, and Science and Technology Facilities Council (STFC)

Subjects
Science & Technology, 0306 Physical Chemistry (Incl. Structural), turbulence, MAGNETIC-FIELD FLUCTUATIONS, ANISOTROPY MEASUREMENTS, Astronomy & Astrophysics, magnetic fields, plasmas, 0305 Organic Chemistry, SOLAR-WIND TURBULENCE, 0201 Astronomical And Space Sciences, solar wind, ELECTRON MAGNETOHYDRODYNAMIC TURBULENCE, Physics::Space Physics, Physical Sciences, COLLISIONLESS SHOCKS, waves, ALFVENIC TURBULENCE, CLUSTER OBSERVATIONS, TAYLOR HYPOTHESIS, DISSIPATION RANGE, ASTROPHYSICAL GYROKINETICS
Abstract

We present a combined observational and theoretical analysis to investigate the nature of plasma turbulence at kinetic scales in the Earth's magnetosheath. In the first decade of the kinetic range, just below the ion gyroscale, the turbulence was found to be similar to that in the upstream solar wind: predominantly anisotropic, low-frequency and kinetic Alfvén in nature. A key difference, however, is that the magnetosheath ions are typically much hotter than the electrons, ${T}_{{\rm{i}}}\gg {T}_{{\rm{e}}}$, which, together with ${\beta }_{{\rm{i}}}\sim 1$, leads to a change in behavior in the second decade, close to electron scales. The turbulence here is characterized by an increased magnetic compressibility, following a mode we term the inertial kinetic Alfvén wave, and a steeper spectrum of magnetic fluctuations, consistent with the prediction ${E}_{B}({k}_{\perp })\propto {k}_{\perp }^{-11/3}$ that we obtain from a set of nonlinear equations. This regime of plasma turbulence may also be relevant for other astrophysical environments with ${T}_{{\rm{i}}}\gg {T}_{{\rm{e}}}$, such as the solar corona, hot accretion flows, and regions downstream of collisionless shocks.

Published
2017

6. Planck intermediate results: XXXV. Probing the role of the magnetic field in the formation of structure in molecular clouds

Author

Ade, P. A. R., Aghanim, N., Alves, M. I. R., Arnaud, M., Arzoumanian, D., Ashdown, M., Aumont, J., Baccigalupi, C., Banday, A. J., Barreiro, R. B., Bartolo, N., Battaner, E., Benabed, K., Benoît, A., Benoit-Lévy, A., Bernard, J.-P., Bersanelli, M., Bielewicz, P., Bock, J. J., Bonavera, L., Bond, J. R., Borrill, J., Bouchet, F. R., Boulanger, F., Bracco, A., Burigana, C., Calabrese, E., Cardoso, J.-F., Catalano, A., Chiang, H. C., Christensen, P. R., Colombo, L. P. L., Combet, C., Couchot, F., Crill, B. P., Curto, A., Cuttaia, F., Danese, L., Davies, R. D., Davis, R. J., De Bernardis, P., De Rosa, A., De Zotti, G., Delabrouille, J., Dickinson, C., Diego, J. M., Dole, H., Donzelli, S., Doré, O., Douspis, M., Ducout, A., Dupac, X., Efstathiou, G., Elsner, F., Enßlin, T. A., Eriksen, H. K., Falceta-Gonçalves, D., Falgarone, E., Ferrière, K., Finelli, F., Forni, O., Frailis, M., Fraisse, A., Franceschi, E., Frejsel, A., Galeotta, S., Galli, S., Ganga, K., Ghosh, T., Giard, M., Gjerløw, E., González-Nuevo, J., Górski, K. M., Gregorio, A., Gruppuso, A., Gudmundsson, J. E., Guillet, V., Harrison, D. L., Helou, G., Hennebelle, P., Henrot-Versille, S., Hernández-Monteagudo, C., Herranz, D., Hildebrandt, S. R., Hivon, E., Holmes, W. A., Hornstrup, A., Huffenberger, K. M., Hurier, G., Jaffe, A. H., Jaffe, T. R., Jones, W. C., Juvela, M., Keihänen, E., Keskitalo, R., Kisner, T. S., Knoche, J., Kunz, M., Kurki-Suonio, H., Lagache, Guilaine, Lamarre, J.-M., Lasenby, A., Lattanzi, M., Lawrence, C. R., Leonardi, R., Levrier, F., Liguori, M., Lilje, P. B., Linden-Vørnle, M., López-Caniego, M., Lubin, P. M., Macías-Pérez, J. F., Maino, D., Mandolesi, N., Mangilli, A., Maris, M., Martin, P. G., Martínez-González, E., Masi, S., Matarrese, S., Melchiorri, A., Mendes, L., Mennella, A., Migliaccio, M., Miville-Deschênes, M.-A., Moneti, A., Montier, L., Morgante, G., Mortlock, D., Munshi, D., Murphy, J. A., Naselsky, P., Nati, F., Netterfield, C. B., Noviello, F., Novikov, D., Novikov, I., Oppermann, N., Oxborrow, C. A., Pagano, L., Pajot, F., Paladini, R., Paoletti, D., Pasian, F., Perotto, L., Pettorino, V., Piacentini, F., Piat, M., Pierpaoli, E., Pietrobon, D., Plaszczynski, S., Pointecouteau, E., Polenta, G., Ponthieu, N., Pratt, G. W., Prunet, S., Puget, J.-L., Rachen, J. P., Reinecke, M., Remazeilles, M., Renault, C., Renzi, A., Ristorcelli, I., Rocha, G., Rossetti, M., Roudier, G., Rubiño-Martín, J. A., Rusholme, B., Sandri, M., Santos, D., Savelainen, M., Savini, G., Scott, D., Soler, J. D., Stolyarov, V., Sudiwala, R., Sutton, D., Suur-Uski, A.-S., Sygnet, J.-F., Tauber, J. A., Terenzi, L., Toffolatti, L., Tomasi, M., Tristram, M., Tucci, M., Umana, G., Valenziano, L., Valiviita, J., Van Tent, B., Vielva, P., Villa, F., Wade, L. A., Wandelt, B. D., Wehus, I. K., Ysard, N., Yvon, D., Zonca, A., Banday, J., Bouchet, R., Chiang, C., Colombo, P., Crill, P., Davies, D., Davis, J., Bernard, P., Diego, M., Enßlin, A., Eriksen, K., Górski, M., Hildebrandt, R., Holmes, A., Huffenberger, M., Jaffe, R., Jones, C., Kisner, S., Lamarre, M., Rachen, P., Soler, D., Wade, A., Wandelt, D., Wehus, K., Hélium : du fondamental aux applications (HELFA), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de l'Accélérateur Linéaire (LAL), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), PLANCK, Scuola Internazionale Superiore di Studi Avanzati / International School for Advanced Studies (SISSA / ISAS), INO-CNR BEC Center and Dipartimento di Fisica, Università degli Studi di Trento (UNITN), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Fisica Nucleare [Milano] (INFN), Laboratoire Traitement et Communication de l'Information (LTCI), Télécom ParisTech-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Physique Corpusculaire et Cosmologie - Collège de France (PCC), Collège de France (CdF)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Steward Observatory, University of Arizona, Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, APC - Cosmologie, Collège de France (CdF)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-AstroParticule et Cosmologie (APC (UMR_7164)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Institut de recherche en astrophysique et planétologie (IRAP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Laboratoire Pluridisciplinaire de Recherche en Ingénierie des Systèmes, Mécanique et Energétique (PRISME), Université d'Orléans (UO)-Ecole Nationale Supérieure d'Ingénieurs de Bourges (ENSI Bourges), Spitzer Science Center, California Institute of Technology, Pasadena, California Institute of Technology (CALTECH), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Cavendish Laboratory, University of Cambridge [UK] (CAM), International Center for Relativistic Astrophysics (ICRA), Università degli Studi di Roma, Laboratoire de Modélisation Multi-échelles des Combustibles (LM2C), Service d'Etudes de Simulation du Comportement du combustibles (SESC), Département d'Etudes des Combustibles (DEC), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Dipartimento di Fisica, Università degli Studi di Roma 'La Sapienza' [Rome], Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Dipartimento di Fisica, Universita` di Roma Tor Vergata, Università degli Studi di Roma Tor Vergata [Roma], AstroParticule et Cosmologie (APC (UMR_7164)), University of Southern California (USC), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), INAF-IASF Milano, Istituto Nazionale di Astrofisica (INAF), Geophysics Centre of Évora, AUTRES, Antarctic Research a European Network for Astrophysics (ARENA), Laboratoire de Physique Théorique d'Orsay [Orsay] (LPT), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Synopsys, Universita degli Studi di Padova, Ade, P, Aghanim, N, Alves, M, Arnaud, M, Arzoumanian, D, Ashdown, M, Aumont, J, Baccigalupi, C, Banday, A, Barreiro, R, Bartolo, N, Battaner, E, Benabed, K, Benoît, A, Benoit Lévy, A, Bernard, J, Bersanelli, M, Bielewicz, P, Bock, J, Bonavera, L, Bond, J, Borrill, J, Bouchet, F, Boulanger, F, Bracco, A, Burigana, C, Calabrese, E, Cardoso, J, Catalano, A, Chiang, H, Christensen, P, Colombo, L, Combet, C, Couchot, F, Crill, B, Curto, A, Cuttaia, F, Danese, L, Davies, R, Davis, R, De Bernardis, P, De Rosa, A, De Zotti, G, Delabrouille, J, Dickinson, C, Diego, J, Dole, H, Donzelli, S, Doré, O, Douspis, M, Ducout, A, Dupac, X, Efstathiou, G, Elsner, F, Enßlin, T, Eriksen, H, Falceta Gonçalves, D, Falgarone, E, Ferrière, K, Finelli, F, Forni, O, Frailis, M, Fraisse, A, Franceschi, E, Frejsel, A, Galeotta, S, Galli, S, Ganga, K, Ghosh, T, Giard, M, Gjerløw, E, González Nuevo, J, Górski, K, Gregorio, A, Gruppuso, A, Gudmundsson, J, Guillet, V, Harrison, D, Helou, G, Hennebelle, P, Henrot Versillé, S, Hernández Monteagudo, C, Herranz, D, Hildebrandt, S, Hivon, E, Holmes, W, Hornstrup, A, Huffenberger, K, Hurier, G, Jaffe, A, Jaffe, T, Jones, W, Juvela, M, Keihänen, E, Keskitalo, R, Kisner, T, Knoche, J, Kunz, M, Kurki Suonio, H, Lagache, G, Lamarre, J, Lasenby, A, Lattanzi, M, Lawrence, C, Leonardi, R, Levrier, F, Liguori, M, Lilje, P, Linden Vørnle, M, López Caniego, M, Lubin, P, Macías Pérez, J, Maino, D, Mandolesi, N, Mangilli, A, Maris, M, Martin, P, Martínez González, E, Masi, S, Matarrese, S, Melchiorri, A, Mendes, L, Mennella, A, Migliaccio, M, Miville Deschênes, M, Moneti, A, Montier, L, Morgante, G, Mortlock, D, Munshi, D, Murphy, J, Naselsky, P, Nati, F, Netterfield, C, Noviello, F, Novikov, D, Novikov, I, Oppermann, N, Oxborrow, C, Pagano, L, Pajot, F, Paladini, R, Paoletti, D, Pasian, F, Perotto, L, Pettorino, V, Piacentini, F, Piat, M, Pierpaoli, E, Pietrobon, D, Plaszczynski, S, Pointecouteau, E, Polenta, G, Ponthieu, N, Pratt, G, Prunet, S, Puget, J, Rachen, J, Reinecke, M, Remazeilles, M, Renault, C, Renzi, A, Ristorcelli, I, Rocha, G, Rossetti, M, Roudier, G, Rubiño Martín, J, Rusholme, B, Sandri, M, Santos, D, Savelainen, M, Savini, G, Scott, D, Soler, J, Stolyarov, V, Sudiwala, R, Sutton, D, Suur Uski, A, Sygnet, J, Tauber, J, Terenzi, L, Toffolatti, L, Tomasi, M, Tristram, M, Tucci, M, Umana, G, Valenziano, L, Valiviita, J, Van Tent, B, Vielva, P, Villa, F, Wade, L, Wandelt, B, Wehus, I, Ysard, N, Yvon, D, Zonca, A, Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Istituto Nazionale di Fisica Nucleare, Sezione di Milano (INFN), Istituto Nazionale di Fisica Nucleare (INFN), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Ade, P. A. R., Aghanim, N., Alves, M. I. R., Arnaud, M., Arzoumanian, D., Ashdown, M., Aumont, J., Baccigalupi, C., Banday, A. J., Barreiro, R. B., Bartolo, N., Battaner, E., Benabed, K., Benoît, A., Benoit Lévy, A., Bernard, J. P., Bersanelli, M., Bielewicz, P., Bock, J. J., Bonavera, L., Bond, J. R., Borrill, J., Bouchet, F. R., Boulanger, F., Bracco, A., Burigana, C., Calabrese, E., Cardoso, J. F., Catalano, A., Chiang, H. C., Christensen, P. R., Colombo, L. P. L., Combet, C., Couchot, F., Crill, B. P., Curto, A., Cuttaia, F., Danese, L., Davies, R. D., Davis, R. J., De Bernardis, P., De Rosa, A., De Zotti, G., Delabrouille, J., Dickinson, C., Diego, J. M., Dole, H., Donzelli, S., Doré, O., Douspis, M., Ducout, A., Dupac, X., Efstathiou, G., Elsner, F., Enßlin, T. A., Eriksen, H. K., Falceta Gonçalves, D., Falgarone, E., Ferrière, K., Finelli, F., Forni, O., Frailis, M., Fraisse, A. A., Franceschi, E., Frejsel, A., Galeotta, S., Galli, S., Ganga, K., Ghosh, T., Giard, M., Gjerløw, E., González Nuevo, J., Górski, K. M., Gregorio, Anna, Gruppuso, A., Gudmundsson, J. E., Guillet, V., Harrison, D. L., Helou, G., Hennebelle, P., Henrot Versillé, S., Hernández Monteagudo, C., Herranz, D., Hildebrandt, S. R., Hivon, E., Holmes, W. A., Hornstrup, A., Huffenberger, K. M., Hurier, G., Jaffe, A. H., Jaffe, T. R., Jones, W. C., Juvela, M., Keihänen, E., Keskitalo, R., Kisner, T. S., Knoche, J., Kunz, M., Kurki Suonio, H., Lagache, G., Lamarre, J. M., Lasenby, A., Lattanzi, M., Lawrence, C. R., Leonardi, R., Levrier, F., Liguori, M., Lilje, P. B., Linden Vørnle, M., López Caniego, M., Lubin, P. M., Macías Pérez, J. F., Maino, D., Mandolesi, N., Mangilli, A., Maris, M., Martin, P. G., Martínez González, E., Masi, S., Matarrese, S., Melchiorri, A., Mendes, L., Mennella, A., Migliaccio, M., Miville Deschênes, M. A., Moneti, A., Montier, L., Morgante, G., Mortlock, D., Munshi, D., Murphy, J. A., Naselsky, P., Nati, F., Netterfield, C. B., Noviello, F., Novikov, D., Novikov, I., Oppermann, N., Oxborrow, C. A., Pagano, L., Pajot, F., Paladini, R., Paoletti, D., Pasian, F., Perotto, L., Pettorino, V., Piacentini, F., Piat, M., Pierpaoli, E., Pietrobon, D., Plaszczynski, S., Pointecouteau, E., Polenta, G., Ponthieu, N., Pratt, G. W., Prunet, S., Puget, J. L., Rachen, J. P., Reinecke, M., Remazeilles, M., Renault, C., Renzi, A., Ristorcelli, I., Rocha, G., Rossetti, M., Roudier, G., Rubiño Martín, J. A., Rusholme, B., Sandri, M., Santos, D., Savelainen, M., Savini, G., Scott, D., Soler, Juan D, Stolyarov, V., Sudiwala, R., Sutton, D., Suur Uski, A. S., Sygnet, J. F., Tauber, J. A., Terenzi, L., Toffolatti, L., Tomasi, M., Tristram, M., Tucci, M., Umana, G., Valenziano, L., Valiviita, J., Van Tent, B., Vielva, P., Villa, F., Wade, L. A., Wandelt, B. D., Wehus, I. K., Ysard, N., Yvon, D., Zonca, A., Science and Technology Facilities Council (STFC), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Hélium : du fondamental aux applications (NEEL - HELFA), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), European Research Council, and European Commission

Subjects
SOLAR NEIGHBORHOOD, magnetic field [ISM], Astronomy, cloud [ISM], Astrophysics, IMAGING POLARIMETRY, 01 natural sciences, ISM: clouds, INTERSTELLAR CLOUDS, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, media_common, Physics, infrared: ISM, general [ISM], Turbulence, extinction, ISM [Submillimeter], Dust, Extinction, VELOCITY ANISOTROPY, Magnetic field, Physical Sciences, Physics::Space Physics, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, symbols, submillimeter: ISM, Astrophysics::Earth and Planetary Astrophysics, ISM: magnetic fields, dust, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], clouds [ISM], FAR-INFRARED POLARIMETRY, GRAIN ALIGNMENT, NUVENS, RADIATIVE TORQUES, Astrophysics::High Energy Astrophysical Phenomena, astro-ph.GA, media_common.quotation_subject, ISM [Infrared], FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, Magnetohydrodynamic turbulence, NO, STAR-FORMATION, Dust, extinction, Infrared: ISM, ISM: general, Submillimeter: ISM, Astronomy and Astrophysics, Space and Planetary Science, symbols.namesake, ISM: magnetic field, Settore FIS/05 - Astronomia e Astrofisica, ISM: cloud, 0103 physical sciences, Planck, Astrophysics::Galaxy Astrophysics, Science & Technology, dust, extinction, 010308 nuclear & particles physics, Plane (geometry), Molecular cloud, magnetic fields [ISM], Astronomy and Astrophysic, Astrophysics - Astrophysics of Galaxies, Orientation (vector space), 0201 Astronomical And Space Sciences, NONHOMOLOGOUS CONTRACTION, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], 13. Climate action, Sky, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), ALFVENIC TURBULENCE
Abstract

Interstellar and circumstellar matter.-- et al., Within ten nearby (d < 450 pc) Gould belt molecular clouds we evaluate statistically the relative orientation between the magnetic field projected on the plane of sky, inferred from the polarized thermal emission of Galactic dust observed by Planck at 353 GHz, and the gas column density structures, quantified by the gradient of the column density, NH. The selected regions, covering several degrees in size, are analysed at an effective angular resolution of 10′ FWHM, thus sampling physical scales from 0.4 to 40 pc in the nearest cloud. The column densities in the selected regions range from NH≈ 1021 to1023 cm-2, and hence they correspond to the bulk of the molecular clouds. The relative orientation is evaluated pixel by pixel and analysed in bins of column density using the novel statistical tool called “histogram of relative orientations”. Throughout this study, we assume that the polarized emission observed by Planck at 353 GHz is representative of the projected morphology of the magnetic field in each region, i.e., we assume a constant dust grain alignment efficiency, independent of the local environment. Within most clouds we find that the relative orientation changes progressively with increasing NH, from mostly parallel or having no preferred orientation to mostly perpendicular. In simulations of magnetohydrodynamic turbulence in molecular clouds this trend in relative orientation is a signature of Alfvénic or sub-Alfvénic turbulence, implying that the magnetic field is significant for the gas dynamics at the scales probed by Planck. We compare the deduced magnetic field strength with estimates we obtain from other methods and discuss the implications of the Planck observations for the general picture of molecular cloud formation and evolution., The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 267934.

Published
2016
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7. Magnetically dominated structures as an important component of the solar wind turbulence

Author

Vincenzo Carbone, Luca Sorriso-Valvo, B. Bavassano, Raffaella D'Amicis, Roberto Bruno, and EGU, Publication

Subjects
Atmospheric Science, RADIAL EVOLUTION, Population, Wind speed, Earth and Planetary Sciences (miscellaneous), Astrophysics::Solar and Stellar Astrophysics, Interplanetary magnetic field, education, lcsh:Science, Physics, education.field_of_study, Flux tube, Magnetic energy, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Ecliptic, CROSS-HELICITY, Geology, Astronomy and Astrophysics, Geophysics, lcsh:QC1-999, Magnetic field, Computational physics, INHOMOGENEOUS MHD TURBULENCE, Solar wind, lcsh:Geophysics. Cosmic physics, Space and Planetary Science, INNER HELIOSPHERE, Physics::Space Physics, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, lcsh:Q, ALFVENIC TURBULENCE, lcsh:Physics
Abstract

This study focuses on the role that magnetically dominated fluctuations have within the solar wind MHD turbulence. It is well known that, as the wind expands, magnetic energy starts to dominate over kinetic energy but we lack of a statistical study apt to estimate the relevance of these fluctuations depending on wind speed, radial distance from the sun and heliographic latitude. Our results suggest that this kind of fluctuations can be interpreted as non-propagating structures, advected by the wind during its expansion. In particular, observations performed in the ecliptic revealed a clear radial dependence of these magnetic structures within fast wind, but not within slow wind. At short heliocentric distances (~0.3 AU) the turbulent population is largely dominated by Alfvénic fluctuations characterized by high values of normalized cross-helicity and a remarkable level of energy equipartition. However, as the wind expands, a new-born population, characterized by lower values of Alfvénicity and a clear imbalance in favor of magnetic energy becomes visible and clearly distinguishable from the Alfvénic population largely characterized by an outward sense of propagation. We estimate that more than 20% of all the analyzed intervals of hourly scale within fast wind are characterized by normalized cross-helicity close to zero and magnetic energy largely dominating over kinetic energy. Most of these advected magnetic structures result to be non-compressive and might represent the crossing of the border between adjacent flux tubes forming, as suggested in literature, the advected background structure of the interplanetary magnetic field. On the other hand, their features are also well fitted by the Magnetic Field Directional Turnings paradigm as proposed in literature.

Published
2007

8. High-resolution hybrid simulations of kinetic plasma turbulence at proton scales

Author

Lorenzo Matteini, Andrea Verdini, Petr Hellinger, Luca Franci, Simone Landi, Science and Technology Facilities Council (STFC), and Science and Technology Facilities Council [2006-2012]

Subjects
astro-ph.SR, Proton, FOS: Physical sciences, Astronomy & Astrophysics, Kinetic energy, 7. Clean energy, SOLAR-WIND TURBULENCE, ENERGY CASCADE, Physics - Space Physics, 0201 Astronomical and Space Sciences, ION, Solar and Stellar Astrophysics (astro-ph.SR), DISSIPATION, 0306 Physical Chemistry (incl. Structural), Physics, SPECTRUM, Range (particle radiation), Science & Technology, 1 AU, Turbulence, turbulence, Astronomy and Astrophysics, Plasma, CURRENT SHEETS, plasmas, plasmas, solar wind, turbulence, Space Physics (physics.space-ph), Computational physics, Solar wind, solar wind, TEMPERATURE ANISOTROPY, Astrophysics - Solar and Stellar Astrophysics, ELECTRON MAGNETOHYDRODYNAMIC TURBULENCE, physics.space-ph, 13. Climate action, Space and Planetary Science, ION SCALES, Energy cascade, Physical Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physics::Space Physics, MAGNETIC FLUCTUATIONS, ALFVENIC TURBULENCE, MAGNETOHYDRODYNAMIC TURBULENCE, Magnetohydrodynamics, DISSIPATION RANGE
Abstract

We investigate properties of plasma turbulence from magneto-hydrodynamic (MHD) to sub-ion scales by means of two-dimensional, high-resolution hybrid particle-in-cell simulations. We impose an initial ambient magnetic field, perpendicular to the simulation box, and we add a spectrum of large-scale magnetic and kinetic fluctuations, with energy equipartition and vanishing correlation. Once the turbulence is fully developed, we observe a MHD inertial range, where the spectra of the perpendicular magnetic field and the perpendicular proton bulk velocity fluctuations exhibit power-law scaling with spectral indices of -5/3 and -3/2, respectively. This behavior is extended over a full decade in wavevectors and is very stable in time. A transition is observed around proton scales. At sub-ion scales, both spectra steepen, with the former still following a power law with a spectral index of ~-3. A -2.8 slope is observed in the density and parallel magnetic fluctuations, highlighting the presence of compressive effects at kinetic scales. The spectrum of the perpendicular electric fluctuations follows that of the proton bulk velocity at MHD scales, and flattens at small scales. All these features, which we carefully tested against variations of many parameters, are in good agreement with solar wind observations. The turbulent cascade leads to on overall proton energization with similar heating rates in the parallel and perpendicular directions. While the parallel proton heating is found to be independent on the resistivity, the number of particles per cell and the resolution employed, the perpendicular proton temperature strongly depends on these parameters., 15 pages, 13 figures, submitted to ApJ

Published
2015

9. The microarcsecond sky and cosmic turbulence

Author

J. M. Cordes, T. Joseph W. Lazio, Jean-Pierre Macquart, A. G. de Bruyn, Kapteyn Astronomical Institute, and Astronomy

Subjects
Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, GALACTIC PLANE, ROTATION MEASURE VARIATIONS, IONIZED-GAS, Pulsar, 0103 physical sciences, Very-long-baseline interferometry, 010306 general physics, 010303 astronomy & astrophysics, Computer Science::Databases, Astrophysics::Galaxy Astrophysics, Physics, Scintillation, Microphysics, INTERSTELLAR-MEDIUM, Scattering, EXTRAGALACTIC RADIO-SOURCES, Astrophysics (astro-ph), Astrophysics::Instrumentation and Methods for Astrophysics, MAGNETIC-FIELD, Astronomy and Astrophysics, Interstellar medium, 13. Climate action, Space and Planetary Science, Intergalactic travel, MAGNETOHYDRODYNAMIC TURBULENCE, ALFVENIC TURBULENCE, SCINTILLATION, GAMMA-RAY EMISSION, Radio wave
Abstract

Radio waves are imprinted with propagation effects from ionized media through which they pass. Owing to electron density fluctuations, compact sources (pulsars, masers, and compact extragalactic sources) can display a wide variety of scattering effects. These scattering effects, particularly interstellar scintillation, can be exploited to provide *superresolution*, with achievable angular resolutions (, Comment: 20 pages, 8 figures in 8 PostScript files, to appear in "Science with the Square Kilometer Array," eds. C. Carilli and S. Rawlings, New Astronomy Reviews (Elsevier: Amsterdam)

Published
2004

10. Relaxed states of Alfvénic turbulence

Author

Vinod Krishan and L. Nocera

Subjects
variational principle, Physics, wave interactions, Turbulence, General Physics and Astronomy, Dissipation, self-organization, Magnetic field, Alfvenic turbulence, symbols.namesake, Classical mechanics, Variational principle, Energy cascade, Physics::Space Physics, solitons, symbols, Soliton, Constant (mathematics), Nonlinear Schrödinger equation
Abstract

By applying the Taylor's relaxation hypothesis, we investigate the relaxed states of the Alfvenic turbulence which is represented here through the Derivative Nonlinear Schroedinger Equation (DNLS). We choose the three lowest order invariants of the DNLS and demonstrate their differential dissipation. We also demonstrate the process of inverse cascade of energy through the mode-mode interaction in the DNLS with dissipation. We perform two variational problems. The variational equation derived using the two lowest-order invariants describes a `constant b', force--free state. However the relaxed state derived using the three lowest order invariants turns out to be equivalent to the steady state of the DNLS. Thus we conclude that the Alfvenic turbulence relaxes or self--organises to a state with soliton type structures which, under certain conditions, approaches the `constant b' force--free state. We believe that the solar wind may be one of physical sites of Alfvenic turbulence to have the right circumstances for the verification of some of these results.

Published
2003
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11. Weak and Strong MHD Turbulence

Author

G. Gogoberidze, S. Mahajan, S. Poedts, M. Akhalkatsi, Ivan Zhelyazkov, Todor Mishonov, Zhelyazkov, I, and Zhelyazkov, I.

Subjects
ANISOTROPY, Physics, Science & Technology, K-epsilon turbulence model, Turbulence, Wave turbulence, Turbulence modeling, Direct numerical simulation, K-omega turbulence model, Magnetohydrodynamic turbulence, SIMULATIONS, Nonlinear Sciences::Chaotic Dynamics, Physics::Fluid Dynamics, Physics, Fluids & Plasmas, turbulence modeling, Physical Sciences, Physics::Space Physics, Turbulence kinetic energy, ALFVENIC TURBULENCE, MAGNETOHYDRODYNAMIC TURBULENCE, INTERSTELLAR TURBULENCE, Statistical physics
Abstract

The general conditions for the weak and strong regimes of incompressible magnetohydrodynamic turbulence are derived and studied in the framework of the direct interaction approximation. It is shown that in the framework of the weak turbulence theory, the autocorrelation and cascade timescales are always of the same order of magnitude. This means that, contrary to the general belief, any model of turbulence which implies a large number of collisions among wave packets for an efficient energy cascade (such as the Iroshnikov–Kraichnan model), does not represent a model of weak turbulence.

Published
2011
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12. Evolution of primordial magnetic fields from phase transitions

Author

Kahniashvili, Tina, Tevzadze, Alexander G., Brandenburg, Axel, Neronov, Andrii, Kahniashvili, Tina, Tevzadze, Alexander G., Brandenburg, Axel, and Neronov, Andrii

Abstract

We consider the evolution of primordial magnetic fields generated during cosmological, electroweak, or QCD phase transitions. We assume that the magnetic field generation can be described as an injection of magnetic energy to cosmological plasma at a given scale determined by the moment of magnetic field generation. A high Reynolds number ensures strong coupling between the magnetic field and fluid motions. The subsequent evolution of the magnetic field is governed by decaying hydromagnetic turbulence. Both our numerical simulations and a phenomenological description allow us to recover "universal'' laws for the decay of magnetic energy and the growth of magnetic correlation length in the turbulent (low-viscosity) regime. In particular, we show that during the radiation-dominated epoch, the energy and correlation length of nonhelical magnetic fields scale as conformal time to the powers -1/2 and +1/2, respectively. For helical magnetic fields, the energy and correlation length scale as conformal time to the powers -1/3 and +2/3, respectively. The universal decay law of the magnetic field implies that the strength of the magnetic field generated during the QCD phase transition could reach similar to 10(-9) G with the present-day correlation length similar to 50 kpc. The fields generated at the electroweak phase transition could be as strong as similar to 10(-10) G with correlation lengths reaching similar to 0.3 kpc. These values of the magnetic fields are consistent with the lower bounds of the extragalactic magnetic fields., QC 20130523

Published
2013
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