Effects of fast and slow solar wind on the energetic neutral atom (ENA) spectra measured by the interstellar boundary explorer (IBEX) at the heliospheric poles

M. A. Dayeh, D. J. McComas, F. Allegrini, B. De Majistre, M. I. Desai, H. O. Funsten, P. Janzen, G. Livadiotis, B. M. Randol, D. B. Reisenfeld, N. A. Schwadron, R. Vanderspek

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

We study the energy dependence of ∼0.5-6keV energetic neutral atom (ENA) spectra in the southern heliospheric polar region obtained during five six-month sky maps measured by IBEX-Hi. We calculate the spectral slopes in the south pole in four different energy bands, namely, ∼0.7-1.1keV, 1.1-1.7keV, ∼1.7-2.7keV, and ∼2.7-4.3keV. We show (1) a persistent flattening of the ENA spectrum between ∼1 and 2keV, (2) significantly different modes (2.31, 1.58, 0.97, and 1.44) for the distributions of the slopes in the four different energy bands, and (3) a general decrease with increasing energy in the widths (FWHM) and mode fluctuations (their spread) of the slope distributions. We also compare the averaged ENA spectra measured at the south pole and at mid-latitudes. We conclude that the flattening between ∼1 and 2keV in the polar spectrum (spectral break) is produced by an enhancement of ENAs created by charge exchange between interstellar neutrals and pick-up ions in the fast solar wind.

Original languageEnglish (US)
Article number50
JournalAstrophysical Journal
Volume749
Issue number1
DOIs
StatePublished - Apr 10 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • ISM: kinematics and dynamics
  • Sun: heliosphere
  • plasmas
  • solar wind

Fingerprint Dive into the research topics of 'Effects of fast and slow solar wind on the energetic neutral atom (ENA) spectra measured by the interstellar boundary explorer (IBEX) at the heliospheric poles'. Together they form a unique fingerprint.

  • Cite this

    Dayeh, M. A., McComas, D. J., Allegrini, F., De Majistre, B., Desai, M. I., Funsten, H. O., Janzen, P., Livadiotis, G., Randol, B. M., Reisenfeld, D. B., Schwadron, N. A., & Vanderspek, R. (2012). Effects of fast and slow solar wind on the energetic neutral atom (ENA) spectra measured by the interstellar boundary explorer (IBEX) at the heliospheric poles. Astrophysical Journal, 749(1), [50]. https://doi.org/10.1088/0004-637X/749/1/50