Low Energy Neutral Atoms From the Heliosheath

Fuselier, S. A.; Allegrini, F.; Bzowski, M.; Dayeh, M. A.; Desai, M. I.; Funsten, H. O.; Galli, André; Heirtzler, D.; Janzen, P. H.; Kubiak, M. A.; Kucharek, H.; Lewis, W. S.; Livadiotis, G.; McComas, D. J.; Möbius, E.; Petrinec, S. M.; Quinn, M.; Schwadron, N. A.; Sokół, J. M.; Trattner, K. J.; Wood, Brian E.; Würz, Peter

doi:10.1088/0004-637x/784/2/89

Cited by 58 publications

(77 citation statements)

References 53 publications

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“…Journal of Geophysical Research: Space Physics 10.1002/2017JA024978 attains its value closest to 1. Figure 4c demonstrates this behavior by coplotting 2 Á P(κ 0max ) À 1 (red) and χ 2 red κ 0 max ð ÞÀ1 (blue), where we observe that they follow a similar path (as explained in Livadiotis, 2014; see also the examples in Frisch et al, 2013;Fuselier et al, 2014), both maximized at κ 0max ≈ 4.5. Nevertheless, the upper limit of kappa indices has not only statistical meaning.…”

Section: Potential Exponentmentioning

confidence: 56%

Using Kappa Distributions to Identify the Potential Energy

Livadiotis

2018

JGR Space Physics

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This paper reports on the properties of kappa distributions in the presence of a potential energy. The constructed phase space kappa distribution leads to a polytropic relationship between the local density and temperature. The kappa and polytropic indices are connected via a characteristic and universal relationship: their sum is a constant depending specifically on the potential features. Determining this constant comprises a method essential for revealing the functional form and understanding the nature of the particle potential energy. The method is applied to the solar wind proton plasma at 1 AU. It is shown that a satisfactory physical interpretation of the potential affecting solar wind protons can be given by the interplanetary radial electric field.

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Section: Potential Exponentmentioning

confidence: 56%

Using Kappa Distributions to Identify the Potential Energy

Livadiotis

2018

JGR Space Physics

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“…The ENA spectral distribution can be generally characterized as a power law (McComas et al 2009b;Livadiotis et al 2011;Dayeh et al 2011;Desai et al 2012Desai et al , 2014Fuselier et al 2014), and the ENA flux likely reaches a maximum near 100 eV ). Variability of spectra over the ENA sky maps indicates the spectra follow the general latitudinal ordering of the solar wind (Funsten et al 2009a;Dayeh et al 2012;McComas et al 2012b;, are influenced by heliospheric pickup ion populations (Livadiotis et al 2012), and may be composed of multiple source ion populations (Desai et al 2014).…”

Section: Introductionmentioning

confidence: 99%

SYMMETRY OF THEIBEXRIBBON OF ENHANCED ENERGETIC NEUTRAL ATOM (ENA) FLUX

Funsten

Bzowski

Cai

et al. 2015

ApJ

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The circular ribbon of enhanced energetic neutral atom (ENA) emission observed by the Interstellar Boundary Explorer (IBEX) mission remains a critical signature for understanding the interaction between the heliosphere and the interstellar medium. We study the symmetry of the ribbon flux and find strong, spectrally dependent reflection symmetry throughout the energy range 0.7-4.3 keV. The distribution of ENA flux around the ribbon is predominantly unimodal at 0.7 and 1.1 keV, distinctly bimodal at 2.7 and 4.3 keV, and a mixture of both at 1.7 keV. The bimodal flux distribution consists of partially opposing bilateral flux lobes, located at highest and lowest heliographic latitude extents of the ribbon. The vector between the ribbon center and heliospheric nose (which defines the so-called BV plane) appears to play an organizing role in the spectral dependence of the symmetry axis locations as well as asymmetric contributions to the ribbon flux. The symmetry planes at 2.7 and 4.3 keV, derived by projecting the symmetry axes to a great circle in the sky, are equivalent to tilting the heliographic equatorial plane to the ribbon center, suggesting a global heliospheric ordering. The presence and energy dependence of symmetric unilateral and bilateral flux distributions suggest strong spectral filtration from processes encountered by an ion along its journey from the source plasma to its eventual detection at IBEX.

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“…In addition to these heliospheric sources, a substantial fraction of the <0.5 keV ENAs in the GDF observed by IBEX-Lo could also originate from suprathermal ions and/or PUIs that exist near the heliopause or beyond in the disturbed LISM region just outside the heliopause known as the outer heliosheath (see Izmodenov et al 2009;Chalov et al 2010;Heerikhuisen et al 2010Heerikhuisen et al , 2014Heerikhuisen & Pogorelov 2011;Fuselier et al 2012Fuselier et al , 2014Opher et al 2013;Desai et al 2014;Zirnstein et al 2014).…”

Section: Introductionmentioning

confidence: 99%

LATITUDINAL AND ENERGY DEPENDENCE OF ENERGETIC NEUTRAL ATOM SPECTRAL INDICES MEASURED BY THEINTERSTELLAR BOUNDARY EXPLORER

Desai

Allegrini

Dayeh

et al. 2015

ApJ

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We investigate the latitudinal and energy dependence of the globally distributed 0.5-6 keV energetic neutral atom (ENA) spectra measured by the Interstellar Boundary Explorer (IBEX) during the first 3 yrs of the mission. Our results are: (1) the ENA spectral indices at the two lowest energies (0.89 and 1.47 keV) exhibit no clear trend with ecliptic latitude θ, while those at ∼2.29 and ∼3.41 keV exhibit a clear latitudinal pattern; flatter spectra occur above 60°latitude and steeper spectra occur ±30°of the equator. with unique offsets, amplitudes, and phase angles; the higher energy ENA indices transition to successively larger amplitudes within ±45°of the equator. Our results confirm the previously reported latitudinal organization of the ENA spectra and their remarkable similarity to that of the solar wind (SW) speed observed by Ulysses in the inner heliosphere. While earlier studies showed that the ∼0.5-6 keV globally distributed ENA spectral indices could be represented as single power laws over much of the sky, our new results indicate that this is an over-simplification because the spectral indices have an energy and latitude dependence. This dependence is an important factor that must be taken into consideration by models and simulations that seek to map the IBEX ENA observations back to the latitudinal profile of the SW speed structure observed in the inner heliosphere.

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Low Energy Neutral Atoms From the Heliosheath

Cited by 58 publications

References 53 publications

Using Kappa Distributions to Identify the Potential Energy

Using Kappa Distributions to Identify the Potential Energy

SYMMETRY OF THEIBEXRIBBON OF ENHANCED ENERGETIC NEUTRAL ATOM (ENA) FLUX

LATITUDINAL AND ENERGY DEPENDENCE OF ENERGETIC NEUTRAL ATOM SPECTRAL INDICES MEASURED BY THEINTERSTELLAR BOUNDARY EXPLORER

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