MAVEN observations of energy-time dispersed electron signatures in Martian crustal magnetic fields

Y. Harada , D. L. Mitchell , J. S. Halekas , J. P. Mcfadden , C. Mazelle (1, 2) , J. E. P. Connerney , J. Espley , D. A. Brain , D. E. Larson , R. J. Lillis , T. Hara , R. Livi , G. A. Dibraccio , S. Ruhunusiri , B. M. Jakosky

1 IRAP - Institut de recherche en astrophysique et planétologie
2 UT - Université de Toulouse

Energy-time dispersed electron signatures are observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission in the vicinity of strong Martian crustal magnetic fields. Analysis of pitch angle distributions indicates that these dispersed electrons are typically trapped on closed field lines formed above strong crustal magnetic sources. Most of the dispersed electron signatures are characterized by peak energies decreasing with time rather than increasing peak energies. These properties can be explained by impulsive and local injection of hot electrons into closed field lines and subsequent dispersion by magnetic drift of the trapped electrons. In addition, the dispersed flux enhancements are often bursty and sometimes exhibit clear periodicity, suggesting that the injection and trapping processes are intrinsically time dependent and dynamic. These MAVEN observations demonstrate that common physical processes can operate in both global intrinsic magnetospheres and local crustal magnetic fields.

Keywords: energy-time dispersion; electrons; Mars; MAVEN; crustal magnetic fields

Domains: Sciences of the Universe [physics]

Y. Harada, D. L. Mitchell, J. S. Halekas, J. P. Mcfadden, C. Mazelle, et al.. MAVEN observations of energy-time dispersed electron signatures in Martian crustal magnetic fields. Geophysical Research Letters, 2016, 43, pp.939-944. ⟨10.1002/2015GL067040⟩. ⟨insu-03670547⟩