HELIOSPHERIC ASYMMETRIES AND 2-3 kHz RADIO EMISSION UNDER STRONG INTERSTELLAR MAGNETIC FIELD CONDITIONS

Pogorelov, N. V.; Heerikhuisen, J.; Mitchell, J. J.; Cairns, Iver H.; Zank, G. P.

doi:10.1088/0004-637x/695/1/l31

Cited by 80 publications

(50 citation statements)

References 29 publications

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“…In their model, ENA emission comes primarily from those regions where the local interstellar (LISM) magnetic field is nearly perpendicular to the line of sight, i.e., B ·r 0 (see also Schwadron et al 2009). The model-predicted ribbon is consistent with both the ENA observations and the magnetic field orientation based on studies of the field draping around the heliopause (Pogorelov et al 2009). The peak in intensity enhancement at 1 keV is explained by the fact that OHS PUIs produced from solar wind ENAs would have approximately that energy (1 keV corresponds to a proton speed of 438 km s −1 ).…”

Section: Introductionsupporting

confidence: 77%

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

Florinski

Zank

Heerikhuisen

et al. 2010

ApJ

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First results from NASA's Interplanetary Boundary Explorer mission showed an unexpected "ribbon" of enhanced energetic neutral atom (ENA) flux spanning most of the sky. One explanation put forward suggests that the ribbon may be produced by secondary ENAs originating from pickup ions (PUIs) in the outer heliosheath (OHS). These PUIs are generated when primary ENAs born in the solar wind and inner heliosheath cross the heliopause and charge exchange in the nearby interstellar medium. One of the core assumptions underpinning this theory is that the newly born PUI ring is relatively stable with respect to wave generation, so that it can undergo charge exchange before becoming isotropized. We test this assumption using a linear kinetic theory and hybrid simulations of a low-density PUI ring interacting with instability-generated waves in a warm plasma of the OHS. It is shown that a broadband spectrum of waves is excited as a result of the cyclotron instability that efficiently scatters the ring ions. We also show that the ambient fluctuations in the OHS are unlikely to produce a measurable degree of resonant scattering of PUIs because their intensity is too low compared with the waves excited by the instability.

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Section: Introductionsupporting

confidence: 77%

“…According to MHD models (e.g., Pogorelov et al 2009) the width of the OHS is on the order of 200 AU, which can be used for Δl above. The PUI differential intensity is f PUI p 2 , which for a ring distribution of thickness Δp in momentum and pitch-angle width ΔΩ may be approximated as…”

Section: Pui Densities In the Outer Heliosheath From Ibex Ena Measurementioning

confidence: 99%

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

Florinski

Zank

Heerikhuisen

et al. 2010

ApJ

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“…Heliosphere models predict the density and ionization of the LIC and the ISMF that shapes the heliosphere (e.g., Opher et al 2009;Pogorelov et al 2009;Ratkiewicz et al 2008;Prested et al 2010) and originally showed that the Ribbon forms where the sight line is perpendicular to the direction of the interstellar field draping over the heliosphere (Schwadron et al 2009;Heerikhuisen et al 2010;Chalov et al 2010;Grygorczuk et al 2011;Heerikhuisen & Pogorelov 2011;Ratkiewicz et al 2012). 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).…”

Section: Appendix a Heliosphere Models And The Ibex Ribbonmentioning

confidence: 99%

“…These models suggest that the Ribbon is formed roughly ∼100 AU beyond the heliopause, by a local ISMF that is directed away from the galactic coordinates The global heliosphere provides an in situ diagnostic of the magnetic field and plasma shaping the heliosphere. The ∼48 • offset between the ISMF direction given by the Ribbon arc center and the velocity of the inflowing neutral interstellar gas creates asymmetries that can be predicted using MHD models (e.g., Pogorelov et al 2009;Opher et al 2009;Ratkiewicz et al 2008;Prested et al 2010). The data tracing the heliosphere asymmetries include the different distances of the solar wind termination shock found by Voyager 1 in the northern ecliptic hemisphere and by Voyager 2 in the south (94 AU versus 84 AU; Stone et al 2008;Richardson & Stone 2009), the ∼8 • offset between the upwind directions of the neutral interstellar H o and He o flowing into the heliosphere (using data from Lallement et al 2010;McComas et al 2012), and the preferential alignment exhibited by the 3 kHz plasma emissions from the ISM beyond the heliopause that were detected by both Voyagers (e.g., Kurth & Gurnett 2003).…”

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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“…Global MHD simulations by Pogorelov et al (2009) confirm this assumption. According to their simulations, the TS is nearly perpendicular, even at higher latitudes.…”

Section: Mhd Simulations Of the Global Shape Of The Termination Shockmentioning

confidence: 54%

The Solar Wind as a Possible Source of Fast Temporal Variations of the Heliospheric Ribbon

Kucharek

Fuselier

Würz

et al. 2013

ApJ

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We present a possible source of pickup ions (PUIs) the ribbon observed by the Interstellar Boundary EXplorer (IBEX). We suggest that a gyrating solar wind and PUIs in the ramp and in the near downstream region of the termination shock (TS) could provide a significant source of energetic neutral atoms (ENAs) in the ribbon. A fraction of the solar wind and PUIs are reflected and energized during the first contact with the TS. Some of the solar wind may be reflected propagating toward the Sun but most of the solar wind ions form a gyrating beamlike distribution that persists until it is fully thermalized further downstream. Depending on the strength of the shock, these gyrating distributions can exist for many gyration periods until they are scattered/thermalized due to wave-particle interactions at the TS and downstream in the heliosheath. During this time, ENAs can be produced by charge exchange of interstellar neutral atoms with the gyrating ions. In order to determine the flux of energetic ions, we estimate the solar wind flux at the TS using pressure estimates inferred from in situ measurements. Assuming an average path length in the radial direction of the order of a few AU before the distribution of gyrating ions is thermalized, one can explain a significant fraction of the intensity of ENAs in the ribbon observed by IBEX. With a localized source and such a short integration path, this model would also allow fast time variations of the ENA flux.

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HELIOSPHERIC ASYMMETRIES AND 2-3 kHz RADIO EMISSION UNDER STRONG INTERSTELLAR MAGNETIC FIELD CONDITIONS

Cited by 80 publications

References 29 publications

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

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

The Interstellar Magnetic Field Close to the Sun. Ii.

The Solar Wind as a Possible Source of Fast Temporal Variations of the Heliospheric Ribbon

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