Lower hybrid waves at comet 67P/Churyumov–Gerasimenko

M. Andre (1) , E. Odelstad (1) , D. B. Graham (1) , A. Eriksson (1) , T. Karlsson (2) , G. Stenberg Wieser (1) , E. Vigren (1) , C. Norgren (1) , F. L. Johansson (1) , Pierre Henri (3) , M. Rubin (4) , I. Richter (5)

1 IRF - Swedish Institute of Space Physics [Uppsala]
2 Department of Space and Plasma Physics [Stockholm]
3 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
4 Physikalisches Institut [Bern]
5 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]

We investigate the generation of waves in the lower hybrid frequency range by density gradients in the near plasma environment of comet 67P/Churyumov–Gerasimenko. When the plasma is dominated by water ions from the comet, a situation with magnetized electrons and unmagnetized ions is favourable for the generation of lower hybrid waves. These waves can transfer energy between ions and electrons and reshape the plasma environment of the comet. We consider cometocentric distances out to a few hundred km. We find that when the electron motion is not significantly interrupted by collisions with neutrals, large average gradients within tens of km of the comet, as well as often observed local large density gradients at larger distances, are often likely to be favourable for the generation of lower hybrid waves. Overall, we find that waves in the lower hybrid frequency range are likely to be common in the near plasma environment.

Keywords: plasmas –waves – comets: general

Domains: Sciences of the Universe [physics]

M. Andre, E. Odelstad, D. B. Graham, A. Eriksson, T. Karlsson, et al.. Lower hybrid waves at comet 67P/Churyumov–Gerasimenko. Monthly Notices of the Royal Astronomical Society, 2017, 469 (Suppl_2), pp.S29 - S38. ⟨10.1093/mnras/stx868⟩. ⟨insu-01670484⟩