Study of multi-periodic coronal pulsations during an X-class solar flare

TL;DR

This study analyzes coronal pulsations during an X-class solar flare, identifying multiple magnetoacoustic wave harmonics and diagnosing plasma conditions through MHD seismology.

Contribution

It provides new insights into coronal pulsations by identifying multiple harmonics and applying MHD seismology to diagnose plasma conditions during a solar flare.

Findings

Multiple periodicities (53 s and 72 s) co-exist in X-ray emissions.

Oscillations are standing fast magnetoacoustic sausage waves.

Period ratio indicates longitudinal density stratification.

Abstract

We investigate quasi-periodic coronal pulsations during the decay phase of an X 3.2 class flare on 14 May 2013, using soft X-ray data from the RHESSI satellite. Periodogram analyses of soft X-ray light curves show that 53 s and 72 s periods co-exist in the 3-6, 6-12 and 12-25 KeV energy bands. Considering the typical length of the flaring loop system and observed periodicities, we find that they are associated with multiple (first two harmonics) of fast magnetoacoustic sausage waves. The phase relationship of soft X-ray emissions in different energy bands using cross-correlation technique show that these modes are standing in nature as we do not find the phase lag. Considering the period ratio, we diagnose the local plasma conditions of the flaring region by invoking MHD seismology. The period ratio P1/2P2 is found to be 0.65, which indicates that such oscillations are most likely excited in longitudinal density stratified loops.