Magnetic Field Strength Fluctuations and Temperature in the Heliosheath

Burlaga, L. F.; Ness, N. F.; Acuña, M. H.

doi:10.1088/0004-637x/691/2/l82

Cited by 32 publications

(39 citation statements)

References 32 publications

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“…(vi) Distributions corresponding to fluctuations of the magnetic field in the plasma within the solar wind in the distant heliosphere and the heliosheath, as detected through data received from the Voyager 1 have been interpreted as q-Gaussians [78,[103][104][105][106][107].…”

Section: Q-gaussian-like Distributions In Nature and Elsewherementioning

confidence: 99%

Nonadditive entropy and nonextensive statistical mechanics -an overview after 20 years

Tsallis¹

2009

Braz. J. Phys.

250

213

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Statistical mechanics constitutes one of the pillars of contemporary physics. Recognized as such -together with mechanics (classical, quantum, relativistic), electromagnetism and thermodynamics -, it is one of the mandatory theories studied at virtually all the intermediate-and advanced-level courses of physics around the world. As it normally happens with such basic scientific paradigms, it is placed at a crossroads of various other branches of knowledge. In the case of statistical mechanics, the standard theory -hereafter referred to as the Boltzmann-Gibbs (BG) statistical mechanics -exhibits highly relevant connections at a variety of microscopic, mesoscopic and macroscopic physical levels, as well as with the theory of probabilities (in particular, with the Central Limit Theorem, CLT ). In many circumstances, the ubiquitous efects of the CLT , with its Gaussian attractors (in the space of the distributions of probabilities), are present. Within this complex ongoing frame, a possible generalization of the BG theory was advanced in 1988 (C.T., J. Stat. Phys. 52, 479). The extension of the standard concepts is intended to be useful in those "pathological", and nevertheless very frequent, cases where the basic assumptions (molecular chaos hypothesis, ergodicity) for applicability of the BG theory would be violated. Such appears to be, for instance, the case in classical long-range-interacting many-body Hamiltonian systems (at the so-called quasi-stationary state). Indeed, in such systems, the maximal Lyapunov exponent vanishes in the thermodynamic limit N → ∞. This fact creates a quite novel situation with regard to typical BG systems, which generically have a positive value for this central nonlinear dynamical quantity. This peculiarity has sensible effects at all physical micro-, meso-and macroscopic levels. It even poses deep challenges at the level of the CLT . In the present occasion, after 20 years of the 1988 proposal, we undertake here an overview of some selected successes of the approach, and of some interesting points that still remain as open questions. Various theoretical, experimental, observational and computational aspects will be addressed.

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Section: Q-gaussian-like Distributions In Nature and Elsewherementioning

confidence: 99%

Nonadditive entropy and nonextensive statistical mechanics -an overview after 20 years

Tsallis¹

2009

Braz. J. Phys.

250

213

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“…Burlaga et al (2007bBurlaga et al ( , 2009a showed that the fluctuations in B observed by V2 behind the TS from 2007 DOY 245-301 ("the post-TS region") were highly variable during intervals of several hours, with large jumps in B on timescales of minutes to a few hours. They found that the distributions of the increments of B are accurately described by the q-Gaussian (Tsallis) distribution of nonextensive statistical mechanics (Balogna et al 2000, Moyno et al 2006, Tsallis 2006a, 2006b, Umarov et al 2006) on scales from 48 s to 6.8 hr, with q ≈ 1.85 -1.9.…”

Section: Introductionmentioning

confidence: 99%

COMPRESSIBLE “TURBULENCE” OBSERVED IN THE HELIOSHEATH BYVOYAGER 2

Burlaga

Ness

2009

ApJ

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This paper describes the multiscale structure of the compressible "turbulence" observed in the high-resolution (48 s) observations of the magnetic field strength B made by Voyager 2 (V2) in the heliosheath behind the termination shock from 2007 DOY 245.0-300.8 and in a unipolar region from 2008 DOY 2.9-75.6. The magnetic field strength is highly variable on scales from 48 s to several hours in both intervals. The distributions of daily averages and 48 s averages of B are lognormal in the post-termination shock (TS) region and Gaussian in the unipolar region, respectively. The amplitudes of the fluctuations were greater in the post-TS region than in the unipolar region, at scales less than several hours. The multiscale structure of the increments of B is described by the q-Gaussian distribution of nonextensive statistical mechanics on all scales from 48 s to 3.4 hr in the unipolar region and from 48 s to 6.8 hr in the post-TS region, respectively. The amplitudes of the fluctuations of increments of B are larger in the post-TS region than in the unipolar region at all scales. The probability density functions of the increments of B are non-Gaussian at all scales in the unipolar region, but they are Gaussian at the largest scales in the post-TS region. Time series of the magnitude and direction of B show that the fluctuations are highly compressive. The small-scale fluctuations are a mixture of coherent structures (semi-deterministic structures) and random structures, which vary significantly from day to day. Several types of coherent structures were identified in both regions.

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“…the entropic parameter q is related to the size of the tail in the distributions [15] and coefficients A q and B q for q > 1 are given by…”

Section: Results and Discussion -mentioning

confidence: 99%

Nonextensive triplet in a geological faults system

Freitas¹,

França²,

Scherrer³

et al. 2013

EPL

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-The San Andreas fault (SAF) in the USA is one of the most investigated selforganizing systems in nature. In this paper, we studied some geophysical properties of the SAF system in order to analyze the behavior of earthquakes in the context of Tsallis's q-Triplet. To that end, we considered 134,573 earthquake events in magnitude interval 2 ≤ m < 8, taken from the Southern Earthquake Data Center (SCEDC, 1932(SCEDC, -2012. The values obtained ("qTriplet"≡{qstat,qsen,q rel }) reveal that the qstat-Gaussian behavior of the aforementioned data exhibit long-range temporal correlations. Moreover, qsen exhibits quasi-monofractal behavior with a Hurst exponent of 0.87.

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Magnetic Field Strength Fluctuations and Temperature in the Heliosheath

Cited by 32 publications

References 32 publications

Nonadditive entropy and nonextensive statistical mechanics -an overview after 20 years

Nonadditive entropy and nonextensive statistical mechanics -an overview after 20 years

COMPRESSIBLE “TURBULENCE” OBSERVED IN THE HELIOSHEATH BYVOYAGER 2

Nonextensive triplet in a geological faults system

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