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Hillebrand M, Katsanikas M, Wiggins S, Skokos C. Navigating phase space transport with the origin-fate map. Phys Rev E 2023; 108:024211. [PMID: 37723690 DOI: 10.1103/physreve.108.024211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/22/2023] [Indexed: 09/20/2023]
Abstract
We introduce and demonstrate the usage of the origin-fate map (OFM) as a tool for the detailed investigation of phase space transport in reactant-product-type systems. For these systems, which exhibit clearly defined start and end states, it is possible to build a comprehensive picture of the lobe dynamics by considering backward and forward integration of sets of initial conditions to index their origin and fate. We illustrate the method and its utility in the study of a two degrees of freedom caldera potential with four exits, demonstrating that the OFM not only recapitulates results from classical manifold theory but even provides more detailed information about complex lobe structures. The OFM allows the detection of dynamically significant transitions caused by the creation of new lobes and is also able to guide the prediction of the position of unstable periodic orbits (UPOs). Further, we compute the OFM on the periodic orbit dividing surface (PODS) associated with the transition state of a caldera entrance, which allows for a powerful analysis of reactive trajectories. The intersection of the manifolds corresponding to this UPO with other manifolds in the phase space results in the appearance of lobes on the PODS, which are directly classified by the OFM. This allows computations of branching ratios and the exploration of a fractal cascade of lobes as the caldera is stretched, which results in fluctuations in the branching ratio and chaotic selectivity. The OFM is found to be a simple and very useful tool with a vast range of descriptive and quantitative applications.
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Affiliation(s)
- Malcolm Hillebrand
- Nonlinear Dynamics and Chaos Group, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany
- Center for Systems Biology Dresden, Pfotenhauer Straße 108, 01307 Dresden, Germany
| | - Matthaios Katsanikas
- Research Center for Astronomy and Applied Mathematics, Academy of Athens, Soranou Efesiou 4, Athens, GR-11527, Greece
- School of Mathematics, University of Bristol, Fry Building, Woodland Road, Bristol, BS8 1UG, United Kingdom
| | - Stephen Wiggins
- School of Mathematics, University of Bristol, Fry Building, Woodland Road, Bristol, BS8 1UG, United Kingdom
- Department of Mathematics, United States Naval Academy, Chauvenet Hall, 572C Holloway Road Annapolis, Maryland 21402-5002, USA
| | - Charalampos Skokos
- Nonlinear Dynamics and Chaos Group, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
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Lemoine M. First-Principles Fermi Acceleration in Magnetized Turbulence. PHYSICAL REVIEW LETTERS 2022; 129:215101. [PMID: 36461966 DOI: 10.1103/physrevlett.129.215101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 09/02/2022] [Accepted: 09/29/2022] [Indexed: 06/17/2023]
Abstract
This Letter provides a concrete implementation of Fermi's model of particle acceleration in magnetohydrodynamic (MHD) turbulence, connecting the rate of energization to the gradients of the velocity of magnetic field lines, which it characterizes within a multifractal picture of turbulence intermittency. It then derives a transport equation in momentum space for the distribution function. This description is shown to be substantiated by a large-scale numerical simulation of strong MHD turbulence. The present general framework can be used to model particle acceleration in a variety of environments.
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Affiliation(s)
- Martin Lemoine
- Institut d'Astrophysique de Paris, CNRS-Sorbonne Université, 98 bis boulevard Arago, F-75014 Paris, France
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Mostafavi P, Burlaga LF, Cairns IH, Fuselier SA, Fraternale F, Gurnett DA, Kim TK, Kurth WS, Pogorelov NV, Provornikova E, Richardson JD, Turner DL, Zank GP. Shocks in the Very Local Interstellar Medium. SPACE SCIENCE REVIEWS 2022; 218:27. [PMID: 35574274 PMCID: PMC9085707 DOI: 10.1007/s11214-022-00893-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 04/15/2022] [Indexed: 05/08/2023]
Abstract
Large-scale disturbances generated by the Sun's dynamics first propagate through the heliosphere, influence the heliosphere's outer boundaries, and then traverse and modify the very local interstellar medium (VLISM). The existence of shocks in the VLISM was initially suggested by Voyager observations of the 2-3 kHz radio emissions in the heliosphere. A couple of decades later, both Voyagers crossed the definitive edge of our heliosphere and became the first ever spacecraft to sample interstellar space. Since Voyager 1's entrance into the VLISM, it sampled electron plasma oscillation events that indirectly measure the medium's density, increasing as it moves further away from the heliopause. Some of the observed electron oscillation events in the VLISM were associated with the local heliospheric shock waves. The observed VLISM shocks were very different than heliospheric shocks. They were very weak and broad, and the usual dissipation via wave-particle interactions could not explain their structure. Estimates of the dissipation associated with the collisionality show that collisions can determine the VLISM shock structure. According to theory and models, the existence of a bow shock or wave in front of our heliosphere is still an open question as there are no direct observations yet. This paper reviews the outstanding observations recently made by the Voyager 1 and 2 spacecraft, and our current understanding of the properties of shocks/waves in the VLISM. We present some of the most exciting open questions related to the VLISM and shock waves that should be addressed in the future.
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Affiliation(s)
- P. Mostafavi
- Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723 USA
| | - L. F. Burlaga
- NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 USA
| | - I. H. Cairns
- School of Physics, University of Sydney, Sydney, NSW 2006 Australia
| | - S. A. Fuselier
- Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249 USA
| | - F. Fraternale
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 USA
| | - D. A. Gurnett
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 USA
| | - T. K. Kim
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 USA
| | - W. S. Kurth
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 USA
| | - N. V. Pogorelov
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 USA
- Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35805 USA
| | - E. Provornikova
- Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723 USA
| | - J. D. Richardson
- Kavli Institute for Astrophysics and Space Research, Cambridge, MA USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA USA
| | - D. L. Turner
- Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723 USA
| | - G. P. Zank
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 USA
- Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35805 USA
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