Investigation of Relationship Between High-Energy X-ray Sources and Photospheric Impact of X1.8 Solar Flare of October 23, 2012 [SSA]

The X-class solar flare of October 23, 2012, generated continuum photospheric emission and a strong helioseismic wave (“sunquake”) that points to an intensive energy release in the dense part of the solar atmosphere. We study properties of the energy release with high temporal and spatial resolutions, using photospheric data from Helioseismic Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO), and hard X-ray observations made by Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). For this analysis we use level-1 HMI data (filtergrams), obtained by scanning the Fe I line (6731 \AA) with time cadence of$\sim 3.6$ s and spatial resolution of $\sim 0.5^{\prime\prime}$ per pixel. It is found that the photospheric disturbances spatially coincide with the region of the hard X-ray emission but are delayed by $\lesssim 4$ seconds. This delay is consistent with predictions of the RADYN models. However, the models fail to explain the magnitude of the observed variations of the HMI lines. The data indicate that the photospheric impact might be caused by the electron energy flux substantially higher than that in the current flare radiative hydrodynamic models.

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I. Sharykin, A. Kosovichev, V. Sadykov, et. al.
Mon, 13 Mar 17

Comments: 19 pages, 5 figures