Observations directly linking chorus to relativistic microbursts: Van Allen Probes and FIREBIRD II

We present observations that definitively establish that discrete whistler mode chorus packets cause relativistic electron microbursts. On Jan 20th, 2016 near 1944 UT the low Earth orbiting CubeSat FIREBIRD II observed energetic microbursts from its lower limit of 220 keV, to 1 MeV. In the outer radiation belt and magnetically conjugate, Van Allen Probe A observed rising-tone, lower band chorus waves with durations and cadences similar to the microbursts. No other waves were observed. A majority of the microbursts do not have the energy dispersion expected for trapped electrons bouncing between mirror points. This confirms that the electrons are rapidly (nonlinearly) scattered into the loss cone by a single coherent interaction with the large amplitude (up to 900 pT) chorus.