Estimation of Reconnection Flux Using Post-eruption Arcades and Its Relevance to Magnetic Clouds at 1 AU

Abstract

We report on a new method to compute the flare reconnection (RC) flux from post-eruption arcades (PEAs) and the underlying photospheric magnetic fields. In previous works, the RC flux has been computed using the cumulative flare ribbon area. Here we obtain the RC flux as the flux in half of the area underlying the PEA in EUV imaged after the flare maximum. We apply this method to a set of 21 eruptions that originated near the solar disk center in Solar Cycle 23. We find that the RC flux from the arcade method (Φ_rA) has excellent agreement with the flux from the flare-ribbon method (Φ_rR) according to Φ_rA=1.24 (Φ^{r_R) 0.99}. We also find Φ_rA to be correlated with the poloidal flux (Φ_P) of the associated magnetic cloud at 1 AU: Φ_P=1.20 (Φ^{r_A) 0.85}. This relation is nearly identical to that obtained by Qiu et al. (Astrophys. J. 659, 758, 2007) using a set of only 9 eruptions. Our result supports the idea that flare reconnection results in the formation of the flux rope and PEA as a common process.