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Home » News & Blogs » EUV-invisible reservoir of solar energetic particles by G. Fleishman et al.*

EUV-invisible reservoir of solar energetic particles by G. Fleishman et al.*

19 Sep 2017, 11:04 UTC
(200 words excerpt, click title or image to see full post)

Large-scale magnetic structures, which likely make a “bridge” between the relatively compact particle acceleration site of a flare energy release and the interplanetary medium, are of particular importance because of their potential role as an “escape route” for solar energetic particles (SEPs). Although these escape routes can sometimes be associated with jets visible in extreme ultraviolet (EUV) and/or soft X-rays (SXRs), the jet plasma must be dense enough to be detected in either EUV or SXR ranges; if tenuous, such escape routes can be undetectable for EUV and SXR instruments. Here the microwave data can help greatly, given that even a relatively low density of nonthermal electrons can render a magnetized volume filled with these particles optically thick at relatively low frequencies and, thus, bright enough to dominate the spectrum. In the optically thick case the brightness temperature from a given LOS is defined by “effective” energy $\langle E \rangle$ of the electrons responsible for emission at the given frequency, $T_{B}=T_{eff}\equiv \langle E \rangle / k_B$, where $k_B$ is the Boltzmann constant. In the Rayleigh-Jeans regime, always valid in the radio domain, the flux density of the optically thick emission is fully specified by three variables: emission frequency $f$, effective ...