skip to main content

DOE PAGESDOE PAGES

Title: Simulations of a dynamic solar cycle and its effects on the interstellar boundary explorer ribbon and globally distributed energetic neutral atom flux

Observations by the Interstellar Boundary Explorer (IBEX) have vastly improved our understanding of the interaction between the solar wind (SW) and local interstellar medium through direct measurements of energetic neutral atoms (ENAs); this informs us about the heliospheric conditions that produced them. An enhanced feature of flux in the sky, the so-called IBEX ribbon, was not predicted by any global models before the first IBEX observations. A dominating theory of the origin of the ribbon, although still under debate, is a secondary charge-exchange process involving secondary ENAs originating from outside the heliopause. According to this mechanism, the evolution of the solar cycle should be visible in the ribbon flux. Therefore, in this paper we simulate a fully time-dependent ribbon flux, as well as globally distributed flux from the inner heliosheath (IHS), using time-dependent SW parameters from Sokol et al. as boundary conditions for our time-dependent heliosphere simulation. After post-processing the results to compute H ENA fluxes, these results show that the secondary ENA ribbon indeed should be time dependent, evolving with a period of approximately 11 yr, with differences depending on the energy and direction. Our results for the IHS flux show little periodic change with the 11 yr solarmore » cycle, but rather with short-term fluctuations in the background plasma. And, while the secondary ENA mechanism appears to emulate several key characteristics of the observed IBEX ribbon, it appears that our simulation does not yet include all of the relevant physics that produces the observed ribbon.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4]
  1. Univ. of Alabama, Huntsville, AL (United States). Center for Space Plasma and Aeronomic Research and Dept. of Physics; Southwest Research Inst. (SwRI), San Antonio, TX (United States)
  2. Univ. of Alabama, Huntsville, AL (United States). Center for Space Plasma and Aeronomic Research and Dept. of Space Science
  3. Southwest Research Inst. (SwRI), San Antonio, TX (United States); Univ. of Texas, San Antonio, TX (United States). Dept. of Physics and Astronomy
  4. Southwest Research Inst. (SwRI), San Antonio, TX (United States)
Publication Date:
Grant/Contract Number:
SC0008334; NNX11AB48G; NNX12AH44G; NNX12AB30G; NNX13AF99G; NNX14AF43G; NNX14AP24G; NNX14AJ53G
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 804; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Univ. of Alabama, Huntsville, AL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); National Aeronautic and Space Administration (NASA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; ISM: atoms; methods: numerical; solar wind; Sun: heliosphere
OSTI Identifier:
1326075