A new 3D solar wind speed and density model based on interplanetary scintillation

Abstract

The solar wind (SW) is an outflow of the solar coronal plasma, expanding supersonically throughout the heliosphere. SW particles interact by charge exchange with interstellar neutral atoms and on one hand, they modify the distribution of this gas in interplanetary space, and on the other hand they are seed population for heliospheric pickup ions and energetic neutral atoms (ENAs). The heliolatitudinal profiles of the SW speed and density evolve during the cycle of solar activity. A model of evolution of the SW speed and density is needed to interpret observations of ENAs, pickup ions, the heliospheric backscatter glow, etc. We derive the Warsaw Heliospheric Ionization Model 3DSW (WawHelIon 3DSW) based on interplanetary scintillation (IPS) tomography maps of the SW speed. We take the IPS tomography data from 1985 until 2020, compiled by \citet{tokumaru_etal:21a}. We derive a novel statistical method of filtering these data against outliers, we present a flexible analytic formula for the latitudinal profiles of the SW speed based on Legendre polynomials of varying order with additional restraining conditions at the poles, fit this formula to the yearly filtered data, and calculate the yearly SW density profiles using the latitudinally invariant SW energy flux, observed in the ecliptic plane. Despite application of refined IPS data set, a more sophisticated data filtering method, and a more flexible analytic model, the present results mostly agree with those obtained previously, which demonstrates the robustness of IPS studies of the SW structure.

Corrected mistake in the text: all cos(phi) -> cos(Pi/2 - phi). Mistake only in text, results unchanged

References in corpus (7)

• Survival probability and energy modification of hydrogen Energetic Neutral Atoms on their way from the termination shock to Earth orbit
• Neutral interstellar He parameters in front of the heliosphere 1994--2007
• Sun-Heliosphere Observation-based Ionization Rates Model
• 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. The Large-scale Structures
• WawHelioGlow: a model of the heliospheric backscatter glow. I. Model definition
• WawHelioGlow: a model of the heliospheric backscatter glow. II. The helioglow buildup and the potential significance of the anisotropy in the solar EUV output

Cited by in corpus (11)

• The gravitational-wave background null hypothesis: Characterizing noise in millisecond pulsar arrival times with the Parkes Pulsar Timing Array
• SRG/eROSITA X-ray shadowing study of giant molecular clouds
• Bayesian Solar Wind Modeling with Pulsar Timing Arrays
• The SRG/eROSITA diffuse soft X-ray background. I. The local hot bubble in the western Galactic hemisphere
• On general correlation between 3D solar wind speed and density model and solar proxies
• Interstellar Neutral Hydrogen in the Heliosphere: New Horizons Observations in the Context of Models
• Backscattered solar Lyman-alpha emission as a tool for the heliospheric boundary exploration
• The flow direction of interstellar neutral H from SOHO/SWAN
• Determining the ionization rates of interstellar neutral species using direct-sampling observations of their direct and indirect beams
• Different polarized components of the quasar 3C 286 revealed by FAST
• Testing the Alfvén-wave model of the solar wind with interplanetary scintillation