Hybrid-Vlasov simulation of soft X-ray emissions at the Earth’s dayside magnetospheric boundaries  

作　　者：M.Grandin H.K.Connor S.Hoilijoki M.Battarbee Y.Pfau-Kempf U.Ganse K.Papadakis M.Palmroth 

机构地区：[1]Department of Physics,University of Helsinki,Helsinki,Finland [2]NASA Goddard Space Flight Center,Greenbelt,MD,20771,USA [3]Space and Earth Observation Centre,Finnish Meteorological Institute,Helsinki,Finland

出　　处：《Earth and Planetary Physics》2024年第1期70-88,共19页地球与行星物理（英文版）

基　　金：the European Research Council for starting grant 200141-QuESpace,with which the Vlasiator model was developed;consolidator grant 682068-PRESTISSIMO awarded for further development of Vlasiator and its use in scientific investigations;Academy of Finland grant numbers 338629-AERGELC’H,339756-KIMCHI,336805-FORESAIL,and 335554-ICT-SUNVAC;The Academy of Finland also supported this work through the PROFI4 grant(grant number 3189131);support from the NASA grants,80NSSC20K1670 and 80MSFC20C0019;the NASA GSFC FY23 IRAD;HIF funds。

摘　　要：Solar wind charge exchange produces emissions in the soft X-ray energy range which can enable the study of near-Earth space regions such as the magnetopause,the magnetosheath and the polar cusps by remote sensing techniques.The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)and Lunar Environment heliospheric X-ray Imager(LEXI)missions aim to obtain soft Xray images of near-Earth space thanks to their Soft X-ray Imager(SXI)instruments.While earlier modeling works have already simulated soft X-ray images as might be obtained by SMILE SXI during its mission,the numerical models used so far are all based on the magnetohydrodynamics description of the space plasma.To investigate the possible signatures of ion-kinetic-scale processes in soft Xray images,we use for the first time a global hybrid-Vlasov simulation of the geospace from the Vlasiator model.The simulation is driven by fast and tenuous solar wind conditions and purely southward interplanetary magnetic field.We first produce global X-ray images of the dayside near-Earth space by placing a virtual imaging satellite at two different locations,providing meridional and equatorial views.We then analyze regional features present in the images and show that they correspond to signatures in soft X-ray emissions of mirrormode wave structures in the magnetosheath and flux transfer events(FTEs)at the magnetopause.Our results suggest that,although the time scales associated with the motion of those transient phenomena will likely be significantly smaller than the integration time of the SMILE and LEXI imagers,mirror-mode structures and FTEs can cumulatively produce detectable signatures in the soft X-ray images.For instance,a local increase by 30%in the proton density at the dayside magnetopause resulting from the transit of multiple FTEs leads to a 12%enhancement in the line-of-sight-and time-integrated soft X-ray emissivity originating from this region.Likewise,a proton density increase by 14%in the magnetosheath associated with mirror-mode structures can resu

关 键 词：MAGNETOSPHERE MAGNETOSHEATH numerical simulation SMILE LEXI soft X-ray emissions hybrid-Vlasov model polar cusp flux transfer events mirror-mode waves 

分 类 号：P172.2[天文地球—天文学]