# Investigation of Relationship Between High-Energy X-ray Sources and Photospheric and Helioseismic Impacts of X1.8 Solar Flare of October 23, 2012

## TL;DR

This study investigates the connection between high-energy X-ray sources and photospheric and helioseismic impacts during the October 23, 2012, X1.8 solar flare, revealing discrepancies between observations and existing models.

## Contribution

It provides high-resolution analysis of flare energy release and highlights the need for models with higher electron energy flux to explain observed impacts.

## Key findings

- Photospheric disturbances coincide with X-ray emission regions but are delayed by less than 4 seconds.
- Observed variations are larger than those predicted by current hydrodynamic models.
- Photospheric impact and helioseismic waves may be caused by electron energy fluxes higher than current models assume.

## Abstract

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 the Helioseismic Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO), and hard X-ray observations made by the 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 the 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 caused by the flare spatially coincide with the region of hard X-ray emission, but are delayed by $\lesssim 4$ seconds. This delay is consistent with predictions of the flare hydrodynamics RADYN models. However, the models fail to explain the magnitude of variations observed by the HMI. The data indicate that the photospheric impact and helioseismic wave might be caused by the electron energy flux substantially higher than that in the current flare radiative hydrodynamic models.