Heliospheric structure as revealed by the 3 -- 88 keV H ENA spectra
arXiv:1911.10019 · doi:10.3847/1538-4357/ab5b14
Abstract
Energetic neutral atoms (ENA) are an important tool for investigating the structure of the heliosphere. Recently, it was observed that fluxes of ENAs (with energy 55 keV) coming from the upwind and downwind regions of the heliosphere are similar in strength. This led the authors of these observations to hypothesize that the heliosphere is bubble-like rather than comet-like, meaning that it has no extended tail. We investigate the directional distribution of the ENA flux for a wide energy range (3--88 keV) including the observations from IBEX (Interstellar Boundary Explorer), INCA (Ion and Neutral Camera, on board Cassini), and HSTOF (High energy Suprathermal Time Of Flight sensor, on board SOHO, Solar and Heliospheric Observatory). An essential element is the model of pickup ion acceleration at the termination shock (TS) proposed by Zank. We use state of the art models of the global heliosphere, interstellar neutral gas density, and pickup ion distributions. The results, based on the "comet-like" model of the heliosphere, are close in flux magnitude to ENA observations by IBEX, HSTOF and partly by INCA (except for the 5.2-13.5 keV energy channel). We find that the ENA flux from the tail dominates at high energy (in agreement with HSTOF, but not INCA). At low energy, our comet-like model produces the similar strengths of the ENA fluxes from the upwind and downwind directions, which, therefore, removes this as a compelling argument for a bubble-like heliosphere.
arXiv commentAccepted for publication in The Astrophysical Journal
References in corpus (21)
- Modeling of the heliospheric interface: multi-component nature of the heliospheric plasma
- Heliolatitude and time variations of solar wind structure from in situ measurements and interplanetary scintillation observations
- Interstellar neutral helium in the heliosphere from IBEX observations. III. Mach number of the flow, velocity vector, and temperature from the first six years of measurements
- Survival probability and energy modification of hydrogen Energetic Neutral Atoms on their way from the termination shock to Earth orbit
- Density of neutral interstellar hydrogen at the termination shock from Ulysses pickup ion observations
- Revisiting Ulysses Observations of Interstellar Helium
- Solar parameters for modeling interplanetary background
- Interstellar neutral helium in the heliosphere from IBEX observations. IV. Flow vector, Mach number, and abundance of the Warm Breeze
- Modulation of neutral interstellar He, Ne, O in the heliosphere. Survival probabilities and abundances at IBEX
- Effects of interstellar and solar wind ionized helium on the interaction of the solar wind with the local interstellar medium
- The Solar Wind Energy Flux
- Neutral interstellar He parameters in front of the heliosphere 1994--2007
- Charting the Interstellar Magnetic Field causing the Interstellar Boundary Explorer (IBEX) Ribbon of Energetic Neutral Atoms
- Neutral H density at the termination shock: a consolidation of recent results
- Reconstruction of Helio-latitudinal Structure of the Solar Wind Proton Speed and Density
- Neutral interstellar hydrogen in the inner heliosphere under the influence of wavelength-dependent solar radiation pressure
- Interstellar Neutral Gas Species And Their Pickup Ions Inside The Heliospheric Termination Shock. Ionization Rates For H, O, Ne, And He
- Plasma pressures in the heliosheath from Cassini ENA and Voyager 2 measurements: Validation by the Voyager 2 heliopause crossing
- Evolution of the Solar Lyman-Alpha line profile during the solar cycle
- Interstellar Neutral Gas Species And Their Pickup Ions Inside The Heliospheric Termination Shock. The Large-scale Structures
- Evolution of the solar Ly- line profile during the solar cycle. II. How accurate is the present radiation pressure paradigm for interstellar neutral H in the heliosphere?