On Recurrent Active Region Jets: Coronal Geyser Magnetic Triggers and Their Link to Electron Beams

Recurrent active region jets are small-scale collimated eruptions observed in active region penumbra. Both the leading cause and implications of the recurrence are not yet fully understood. We started by analyzing the eruption mechanism responsible for at least ten observed recurrent jets, all occurring at the south-eastern penumbral boundary of AR11302. The analysis lead to the discovery of a peculiar lower corona arched structure. We introduce the terminology “Coronal Geyser” to define its properties. The relation between the jet origin and other dynamic plasma features, such as pre/post flare magnetic configuration, low lying coronal loops, non-thermal electrons, is amply discussed. The identified events were observed in EUV and were correlated with corresponding low-lying magnetic features using vector magnetograms. The accurate detection of local magnetic fields is essential. We report that the two widely debated magnetic jet trigger processes, namely magnetic flux cancellation and magnetic flux emergence, appear to be responsible on a case by case basis for generating each eruption in our set. We then expanded our dataset to contain 6 independent Geysers. Jet eruptions have been associated with Type-III radio bursts that are manifestations of traveling non-thermal electron beams. We examine the assumed link, as the coronal sources of interplanetary Type-III bursts are still open for debate. We temporally correlated and then causally linked the six Geysers that released at least 50 recurrent jets with correspondent Type-III radio bursts detected in the interplanetary medium, showing that Geysers act as coronal sources for Type-III bursts, and, implicitly, upward accelerated electron beams.