STABILITY OF A PICKUP ION RING-BEAM POPULATION IN THE OUTER HELIOSHEATH: IMPLICATIONS FOR THE<i>IBEX</i>RIBBON

Florinski, V.; Zank, G. P.; Heerikhuisen, J.; Hu, Qiang; Khazanov, Igor

doi:10.1088/0004-637x/719/2/1097

Cited by 85 publications

(82 citation statements)

References 42 publications

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“…This method allows us to produce a ribbon intensity that peaks near directions toward B · r = 0, and diminishes farther away. The dynamics of PUIs in the OHS are likely more complicated, such that parallel-propagating PUIs may not scatter as easily as PUIs with large pitch angles (e.g., Isenberg 2014), PUIs produced near B · r = 0 may scatter onto nearly full shell distributions (Florinski et al 2010;Isenberg 2014), PUIs may experience little to no net scattering (Chalov et al 2010;Möbius et al 2013), or become trapped in preexisting LISM magnetic field turbulence (Giacalone & Jokipii 2015), depending on the behavior of the PUIs and the level of turbulence in the OHS. For example, recent observations by Voyager 1 suggest that the OHS has unexpectedly low levels of turbulence (Burlaga et al , 2015.…”

Section: Simulating the Ibex Ribbonmentioning

confidence: 99%

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Effects of solar wind speed on the secondary energetic neutral source of the Interstellar Boundary Explorer ribbon

Zirnstein

Funsten

Heerikhuisen

et al. 2016

A&A

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The Interstellar Boundary EXplorer (IBEX) ribbon is an intense energetic neutral atom (ENA) emission feature encircling the sky, spanning energies ≤0.5-6 keV. The ribbon may be produced by the "secondary ENA" mechanism, where ENAs emitted from a source plasma population inside the heliosphere propagate outside the heliopause, undergo two charge-exchange events, and become secondary ENAs that may be directed back toward Earth and detected by IBEX. In this scenario, the source plasma population is governed by the interaction of the solar wind (SW) with the interstellar medium and is thus sensitive to the global SW properties. Moreover, this scenario predicts that the distance to the source of secondary ENAs depends on the ENA energy and SW speed, which in turn may affect the shape of the ribbon. In this paper, we use a computational model of the heliosphere with simplified SW boundary conditions to analyze the influence of ENA energy and SW speed, independent of time and latitude, on the global spatial and geometric properties of the ribbon. We find a strong dependence of the simulated ribbon energy spectrum and spatial symmetry on SW speed and ENA energy, and only a slight dependence on ribbon geometry. Our results suggest a significant number of primary ENAs from the inner heliosheath may contribute to the pickup ion source population outside the heliopause, depending on the ENA energy and SW speed. The lack of variation in the simulated ribbon center as a function of ENA energy and SW speed, in contrast to the observations, implies that the asymmetry of the SW plays an important role in determining the position of the ribbon. Comparisons to the IBEX data also signify the ribbon's dependence on the properties of the local interstellar medium, particularly the interstellar magnetic field.

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Section: Simulating the Ibex Ribbonmentioning

confidence: 99%

“…The details of the parent PUI dynamics in the OHS, however, are still under debate (also see Florinski et al 2010;Gamayunov et al 2010;Liu et al 2012;Summerlin et al 2014;Zank et al 2014). …”

Section: Introductionmentioning

confidence: 99%

Effects of solar wind speed on the secondary energetic neutral source of the Interstellar Boundary Explorer ribbon

Zirnstein

Funsten

Heerikhuisen

et al. 2016

A&A

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“…The exact mechanism generating the Ribbon is a conundrum, partly because the properties of turbulence upstream of the heliopause are unknown (Gamayunov et al 2010;Florinski et al 2010), so that several possible scenarios for the formation of the Ribbon have been suggested (e.g., McComas et al 2010;Schwadron et al 2011;Grzedzielski et al 2010). One possible Ribbon formation mechanism requires outflowing ENAs to escape from the heliosphere and charge exchange with interstellar protons in the outer heliosheath.…”

Section: Appendix a Heliosphere Models And The Ibex Ribbonmentioning

confidence: 99%

The Interstellar Magnetic Field Close to the Sun. Ii.

Frisch

Andersson

Berdyugin

et al. 2012

ApJ

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The magnetic field in the local interstellar medium (ISM) provides a key indicator of the galactic environment of the Sun and influences the shape of the heliosphere. We have studied the interstellar magnetic field (ISMF) in the solar vicinity using polarized starlight for stars within 40 pc of the Sun and 90 • of the heliosphere nose. In Frisch et al. (Paper I), we developed a method for determining the local ISMF direction by finding the best match to a group of interstellar polarization position angles obtained toward nearby stars, based on the assumption that the polarization is parallel to the ISMF. In this paper, we extend the analysis by utilizing weighted fits to the position angles and by including new observations acquired for this study. We find that the local ISMF is pointed toward the • 25 pc −1 . This conclusion is conditioned on the small sample of stars available for defining this rotation. Variations from the ordered component suggest a turbulent component of ∼23 • . The ordered component and standard relations between polarization, color excess, and H o column density predict a reasonable increase of N(H) with distance in the local ISM. The similarity of the ISMF directions traced by the polarizations, the IBEX Ribbon, and pulsars inside the Local Bubble in the third galactic quadrant suggest that the ISMF is relatively uniform over spatial scales of 8-200 pc and is more similar to interarm than spiral-arm magnetic fields. The ISMF direction from the polarization data is also consistent with small-scale spatial asymmetries detected in GeV-TeV cosmic rays with a galactic origin. The peculiar geometrical relation found earlier between the cosmic microwave background dipole moment, the heliosphere nose, and the ISMF direction is supported by this study. The interstellar radiation field at ∼975 Å does not appear to play a role in grain alignment for the low-density ISM studied here.

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“…The ribbon was subsequently separated from the globally distributed flux, revealing local maxima and minima in ENA intensity from the nose, tail, and flanks of the heliosphere (Schwadron et al 2011. Due to the large number of observables that the secondary ENA mechanism can explain (see Zirnstein et al 2015a, and references therein), it is widely believed that the ribbon is formed by secondary charge exchange in the outer heliosheath, with many different interpretations of the physical processes governing the parent ions (McComas et al 2009a;Chalov et al 2010;Florinski et al 2010;Gamayunov et al 2010;Heerikhuisen et al 2010;Liu et al 2012;Möbius et al 2013;Isenberg 2014Isenberg , 2015Summerlin et al 2014;Giacalone & Jokipii 2015). The ribbon's position in the sky over all energies was used to determine the pristine interstellar magnetic field (ISMF) vector (Zirnstein et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Geometry and Characteristics of the Heliosheath Revealed in the First Five Years of Interstellar Boundary Explorer Observations

Zirnstein

Funsten

Heerikhuisen

et al. 2016

ApJ

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We investigate and interpret the geometry and characteristics of the inner heliosheath (IHS) plasma and their impact on the heliotail structure as observed in energetic neutral atom (ENA) maps acquired during the first 5 yr of Interstellar Boundary Explorer (IBEX) observations. In particular, IBEX observations of the heliotail reveal distinct, localized emission features (lobes) that provide a rich set of information about the properties and evolution of the heliosheath plasma downstream of the termination shock (TS). We analyze the geometry of the heliotail lobes and find that the plane intersecting the port and starboard heliotail lobe centers is ∼6°from the solar equatorial plane, and the plane intersecting the north and south heliotail lobe centers is ∼90°from the solar equatorial plane, both indicating strong correlation with the fast-slow solar wind asymmetry, and thus reflecting the structure of the IHS flow around the Sun. We also analyze the key parameters and processes that form and shape the port and starboard lobes, which are distinctly different from the north and south lobes. By comparing IBEX ENA observations with results from a simplistic flow model of the heliosphere and a multicomponent description for pickup ions (PUIs) in the IHS, we find that the port and starboard lobe formation is driven by a thin IHS, large nose-tail asymmetry of the distance to the TS (and consequently, a large nose-tail asymmetry of the relative abundance of PUIs at the TS) and the energy-dependent removal of PUIs by charge exchange in the IHS.

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STABILITY OF A PICKUP ION RING-BEAM POPULATION IN THE OUTER HELIOSHEATH: IMPLICATIONS FOR THEIBEXRIBBON

Cited by 85 publications

References 42 publications

Effects of solar wind speed on the secondary energetic neutral source of the Interstellar Boundary Explorer ribbon

Effects of solar wind speed on the secondary energetic neutral source of the Interstellar Boundary Explorer ribbon

The Interstellar Magnetic Field Close to the Sun. Ii.

Geometry and Characteristics of the Heliosheath Revealed in the First Five Years of Interstellar Boundary Explorer Observations

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