Spatial and temporal analysis of 3-minute oscillations in the chromosphere associated with the X2.2 Solar Flare on 2011 February 15

TL;DR

This study analyzes the spatial and temporal behavior of 3-minute chromospheric oscillations around a major solar flare, revealing localized power increases linked to energy injection by nonthermal particles, supporting the acoustic cutoff response theory.

Contribution

It provides detailed spatial-temporal analysis of chromospheric oscillations during a solar flare, highlighting localized power enhancements and their relation to energy injection mechanisms.

Findings

Higher 3-minute power during the flare, concentrated in small areas.

Localized oscillations suggest non-global chromospheric response.

Correlation between oscillation sites and nonthermal particle energy injection.

Abstract

3-minute oscillations in the chromosphere are attributed to both slow magnetoacoustic waves propagating from the photosphere, and to oscillations generated within the chromosphere itself at its natural frequency as a response to a disturbance. Here we present an investigation of the spatial and temporal behavior of the chromospheric 3-minute oscillations before, during, and after the SOL2011-02-15T01:56 X2.2 flare. Observations in ultraviolet emission centered on 1600 and 1700 Angstroms obtained at 24- second cadence from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory are used to create power maps as functions of both space and time. We observe higher 3-minute power during the flare, spatially concentrated in small areas 10 pixels (4 arcseconds) across. This implies that the chromospheric plasma is not oscillating globally as a single body. The locations of increased 3-minute power are consistent with observations of HXR flare emission from previous studies, suggesting that these small areas are manifestations of the chromosphere responding to injection of energy by nonthermal particles. This supports the theory that the chromosphere oscillates at the acoustic cutoff frequency in response to a disturbance.