Time Dependence of the IBEX Ribbon and the Globally Distributed Energetic Neutral Atom Flux Using the First 9 Years of Observations

Schwadron, N. A.; Allegrini, F.; Bzowski, M.; Christian, E. R.; Dayeh, M. A.; Desai, M. I.; Fairchild, K.; Frisch, P. C.; Funsten, H. O.; Fuselier, S. A.; Galli, A.; Janzen, P.; Kubiak, M. A.; McComas, D. J.; Moebius, E.; Reisenfeld, D. B.; Sokół, J. M.; Swaczyna, P.; Szalay, J. R.; Wurz, P.; ... (2018). Time Dependence of the IBEX Ribbon and the Globally Distributed Energetic Neutral Atom Flux Using the First 9 Years of Observations. Astrophysical journal - supplement series, 239(1), p. 1. Institute of Physics Publishing IOP 10.3847/1538-4365/aae48e

[img]
Preview
Text
pdf.pdf - Published Version
Available under License Publisher holds Copyright.

Download (27MB) | Preview

Observations from the Interstellar Boundary Explorer (IBEX) of energetic neutral atoms (ENAs) reveal two populations, those emitted from a narrow (∼20°–40°) ribbon that is centered on the local interstellar magnetic field, and a globally distributed flux (GDF) that is controlled by processes in the heliosheath. This is a third study utilizing a previously developed technique to separate ENA emissions in the ribbon from the GDF. In the first ribbon separation study, we analyzed the first year of IBEX data at the energies of 0.7 keV and above; the second study analyzed data down to 0.2 keV using the first five years of IBEX data. Here, we utilize the separation analysis from 0.7 keV and above to study time evolution in 3 year intervals over the first nine years of IBEX data. This study is the first to reveal the global time evolution of the GDF distinct from that of the IBEX ribbon. We show that the time evolution of the GDF within 40° of the upwind pressure maximum is driven by changes in the solar wind ram pressure through compression and rarefaction in the heliosheath. In contrast, the GDF is relatively stable in the region centered on the heliotail downwind with respect to the interstellar flow. The evolution of the IBEX ribbon is observed to have a time lag with respect to the upwind GDF evolution, likely due to the secondary (neutral) solar wind source. The time lag observed in the ribbon evolution is consistent with the generation of ions retained for several years beyond the heliopause. These observations lend further support to secondary solar wind models of the IBEX ribbon, but also require that there is a significant several year time lag for reneutralization of ions that form the IBEX ribbon. We use this study of the 9 year separation of the IBEX ribbon from the globally distributed flux to prepare for a formal IBEX data release of ribbon and globally distributed flux maps to the heliophysics community.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute

UniBE Contributor:

Galli, André and Wurz, Peter

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science > 530 Physics

ISSN:

0067-0049

Publisher:

Institute of Physics Publishing IOP

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

20 Dec 2018 15:37

Last Modified:

23 Dec 2018 02:33

Publisher DOI:

10.3847/1538-4365/aae48e

BORIS DOI:

10.7892/boris.122695

URI:

https://boris.unibe.ch/id/eprint/122695

Actions (login required)

Edit item Edit item
Provide Feedback