Decrease in magnetosheath jet production due to conditions within
Coronal Mass Ejections
Abstract
Magnetosheath jets are dynamic pressure enhancements observed in the
terrestrial magnetosheath. Their generation mechanisms are currently
debated but can be linked to foreshock processes. Recent results showed
that jets are less numerous when coronal mass ejections (CME) cross the
magnetosheath. Here, we show for the first time how CMEs and their
magnetic ejecta (ME) region are related to jet production. Based on
THEMIS and OMNI data covering 2008–2021, we show the probability
distribution of jet production in 2D parameter histograms using the IMF
cone angle and Alfvén Mach number. We compare this distribution with the
values within CME-MEs. We find high cone angles and low Alfvén Mach
numbers within CME-MEs, which both are unfavorable for jet production as
they may inhibit a proper foreshock region. We predict that future
missions, measuring the magnetosheath of Mercury, will find low numbers
of jets due to low Alfvén Mach numbers.