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Wilson LB, Koval A, Szabo A, Stevens ML, Kasper JC, Cattell CA, Krasnoselskikh VV. Revisiting the structure of low-Mach number, low-beta, quasi-perpendicular shocks. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2017; 122:9115-9133. [PMID: 30410850 PMCID: PMC6219398 DOI: 10.1002/2017ja024352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A study of the structure of 145 low-Mach number (M ≤ 3), low-beta (β ≤ 1), quasi-perpendicular interplanetary collisionless shock waves observed by the Wind spacecraft has provided strong evidence that these shocks have large-amplitude whistler precursors. The common occurrence and large amplitudes of the precursors raise doubts about the standard assumption that such shocks can be classified as laminar structures. This directly contradicts standard models. In 113 of the 145 shocks (~78%), we observe clear evidence of magnetosonic-whistler precursor fluctuations with frequencies ~0.1-7 Hz. We find no dependence on the upstream plasma beta, or any other shock parameter, for the presence or absence of precursors. The majority (~66%) of the precursors propagate at ≤45° with respect to the upstream average magnetic field and most (~87%) propagate ≥30° from the shock normal vector. Further, most (~79%) of the waves propagate at least 20° from the coplanarity plane. The peak-to-peak wave amplitudes (δB pk-pk) are large with a range of maximum values for the 113 precursors of ~0.4-13 nT with an average of ~2 nT. When we normalize the wave amplitudes to the upstream averaged magnetic field and the shock ramp amplitude, we find average values of ~40% and ~220%, respectively.
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Affiliation(s)
- L B Wilson
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - A Koval
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Goddard Planetary Heliophysics Institute, University of Maryland, Baltimore County, Baltimore, Maryland, USA
| | - A Szabo
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - M L Stevens
- Harvard-Smithsonian Center for Astrophysics, Harvard University, Cambridge, Massachusetts, USA
| | - J C Kasper
- School of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - C A Cattell
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, USA
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Malkov MA, Diamond PH, Sagdeev RZ. Proton-helium spectral anomaly as a signature of cosmic ray accelerator. PHYSICAL REVIEW LETTERS 2012; 108:081104. [PMID: 22463513 DOI: 10.1103/physrevlett.108.081104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Indexed: 05/31/2023]
Abstract
The much-anticipated proof of cosmic ray (CR) acceleration in supernova remnants must hinge on the full consistency of acceleration theory with the observations; direct proof is impossible because of CR-orbit scrambling. Recent observations indicate deviations between helium and proton CR rigidity spectra inconsistent with the theory. By considering an initial (injection) phase of the diffusive shock acceleration, where elemental similarity does not apply, we demonstrate that the spectral difference is, in fact, a unique signature of the acceleration mechanism. Collisionless shocks inject more He(2+) when they are stronger and so produce harder He(2+) spectra. The injection bias is due to Alfvén waves driven by the more abundant protons, so the He(2+) ions are harder to trap by these waves. By fitting the p/He ratio to the PAMELA data, we bolster the diffusive shock acceleration case for resolving the century-old mystery of CR origin.
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Affiliation(s)
- M A Malkov
- CASS and Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
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Dimmock AP, Balikhin MA, Krasnoselskikh VV, Walker SN, Bale SD, Hobara Y. A statistical study of the cross-shock electric potential at low Mach number, quasi-perpendicular bow shock crossings using Cluster data. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011ja017089] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sundkvist D, Krasnoselskikh V, Bale SD, Schwartz SJ, Soucek J, Mozer F. Dispersive nature of high mach number collisionless plasma shocks: Poynting flux of oblique whistler waves. PHYSICAL REVIEW LETTERS 2012; 108:025002. [PMID: 22324692 DOI: 10.1103/physrevlett.108.025002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Indexed: 05/31/2023]
Abstract
Whistler wave trains are observed in the foot region of high Mach number quasiperpendicular shocks. The waves are oblique with respect to the ambient magnetic field as well as the shock normal. The Poynting flux of the waves is directed upstream in the shock normal frame starting from the ramp of the shock. This suggests that the waves are an integral part of the shock structure with the dispersive shock as the source of the waves. These observations lead to the conclusion that the shock ramp structure of supercritical high Mach number shocks is formed as a balance of dispersion and nonlinearity.
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Affiliation(s)
- David Sundkvist
- Space Sciences Laboratory, University of California, Berkeley, California, USA.
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Hobara Y, Balikhin M, Krasnoselskikh V, Gedalin M, Yamagishi H. Statistical study of the quasi-perpendicular shock ramp widths. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010ja015659] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Y. Hobara
- Department of Electronic Engineering and Research Station on Seismo Electromagnetics; University of Electro-Communications; Chofu Japan
- ACSE; University of Sheffield; Sheffield UK
| | | | | | - M. Gedalin
- Department of Physics; Ben-Gurion University; Beer-Sheva Israel
| | - H. Yamagishi
- National Institute of Polar Research; Tokyo Japan
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Matsukiyo S, Scholer M. On microinstabilities in the foot of high Mach number perpendicular shocks. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005ja011409] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Tsurutani BT, Smith EJ, Burton ME, Arballo JK, Galvan C, Zhou XY, Southwood DJ, Dougherty MK, Glassmeier KH, Neubauer FM, Chao JK. Oblique “1-Hz” whistler mode waves in an electron foreshock: The Cassini near-Earth encounter. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001ja900108] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Klimas AJ, Valdivia JA, Vassiliadis D, Baker DN, Hesse M, Takalo J. Self-organized criticality in the substorm phenomenon and its relation to localized reconnection in the magnetospheric plasma sheet. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999ja000319] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sckopke N, Paschmann G, Brinca AL, Carlson CW, Lühr H. Ion thermalization in quasi-perpendicular shocks involving reflected ions. ACTA ACUST UNITED AC 1990. [DOI: 10.1029/ja095ia05p06337] [Citation(s) in RCA: 186] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Burgess D, Wilkinson WP, Schwartz SJ. Ion distributions and thermalization at perpendicular and quasi-perpendicular supercritical collisionless shocks. ACTA ACUST UNITED AC 1989. [DOI: 10.1029/ja094ia07p08783] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Winske D, Quest KB. Magnetic field and density fluctuations at perpendicular supercritical collisionless shocks. ACTA ACUST UNITED AC 1988. [DOI: 10.1029/ja093ia09p09681] [Citation(s) in RCA: 157] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Scudder JD, Mangeney A, Lacombe C, Harvey CC, Wu CS, Anderson RR. The resolved layer of a collisionless, high β, supercritical, quasi-perpendicular shock wave: 3. Vlasov electrodynamics. ACTA ACUST UNITED AC 1986. [DOI: 10.1029/ja091ia10p11075] [Citation(s) in RCA: 74] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Scudder JD, Mangeney A, Lacombe C, Harvey CC, Aggson TL, Anderson RR, Gosling JT, Paschmann G, Russell CT. The resolved layer of a collisionless, high β, supercritical, quasi-perpendicular shock wave: 1. Rankine-Hugoniot geometry, currents, and stationarity. ACTA ACUST UNITED AC 1986. [DOI: 10.1029/ja091ia10p11019] [Citation(s) in RCA: 141] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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