Are CME ``interactions'' really important for accelerating major solar energetic particle events?
Szabo, Adam; Richardson, Ian G.; Haggerty, Dennis K.; Kucera, Therese A.; Lawrence, Gareth R.
Abstract
Recent studies have proposed that the presence or absence of an ``interaction'' with a preceding coronal mass ejection (CME) or other coronal structure within ~50 Rs of the Sun discriminates large, fast CMEs associated with major solar energetic particle (SEP) events from those that are not. We conclude that there is no compelling evidence that, if such interactions take place, they play an important role in SEP acceleration. Reasons include: The reported statistical results are consistent with a chance association between interacting CMEs and SEP events; Energetic SEPs are detected at Earth typically before or around the time when the ``primary'' CME enters the LASCO C2 field of view - interactions higher in the corona cannot play a role in acceleration of these particles; For ~60% of major SEP events in 1997-2001, the preceding CME fades into the background corona or is relatively narrow (<40°), suggesting any interaction will be weak; Radio signatures attributed to CME interaction occur after SEP acceleration has commenced.