前震扰动产生的相对论电子
Relativistic electrons produced by foreshock disturbances
摘要：
前震扰动--由超热离子（>100 eV至100 keV）[3，4]产生的大规模（~1000 km至> 30，000 km）、瞬态（每天~5-10次-持续~ 10秒至几分钟）结构[1，2] --出现在地球弓形激波的上游，弓形激波由太阳风与地球磁层碰撞形成。最近发现它们可以将离子加速到几keV的能量[5，6]。虽然土星高马赫数（M > 40）弓形激波中的电子可以被加速到相对论能量（接近1000 keV）[7]，但迄今为止人们认为，在弱得多的（M < 20）地球弓形激波中，电子的加速不可能超过几十keV [8]。在这里，我们报告的观测电子激发的前震扰动的能量至少为300千电子伏。虽然这种高能电子以前曾被报道过，但它们的存在被归因于逃逸的磁层粒子[9，10]或太阳事件[11]。这些相对论性电子与任何太阳活动都无关，也不是磁层起源的。此外，当前前震扰动中离子加速的理论不能解释加速到观测到的相对论能量的电子[12-17]。这些电子显然来自扰动，我们无法解释它们的起源。
英文摘要：
Foreshock disturbances -- large-scale (~1000 km to >30,000 km), transient (~5-10 per day - lasting ~10s of seconds to several minutes) structures [1,2] - generated by suprathermal (>100 eV to 100s of keV) ions [3,4] arise upstream of Earth's bow shock formed by the solar wind colliding with the Earth's magnetosphere. They have recently been found to accelerate ions to energies of several keV [5,6]. Although electrons in Saturn's high Mach number (M > 40) bow shock can be accelerated to relativistic energies (nearly 1000 keV) [7], it has hitherto been thought impossible to accelerate electrons at the much weaker (M < 20) Earth's bow shock beyond a few 10s of keV [8]. Here we report observations of electrons energized by foreshock disturbances to energies up to at least ~300 keV. Although such energetic electrons have been previously reported, their presence has been attributed to escaping magnetospheric particles [9,10] or solar events [11]. These relativistic electrons are not associated with any solar activity nor are they of magnetospheric origin. Further, current theories of ion acceleration in foreshock disturbances cannot account for electrons accelerated to the observed relativistic energies [12-17]. These electrons are clearly coming from the disturbances, leaving us with no explanation as to their origin.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
