# A New Analysis Procedure for Detecting Periodicities within Complex Solar Coronal Arcades

## TL;DR

This paper introduces a novel spatio-temporal auto-correlation analysis method to detect and study periodic oscillations in complex solar coronal arcades, revealing decayless oscillations previously observed only in non-flaring loops.

## Contribution

The paper presents a new auto-correlation based analysis procedure that effectively detects multiple periodicities in complex solar coronal structures, outperforming traditional methods in challenging conditions.

## Key findings

- Detected a dominant 12.5-minute periodicity in large-amplitude oscillations.
- Discovered 8-minute and 10-minute decayless oscillations in the same arcade.
- Validated the new method against traditional time-distance fitting results.

## Abstract

We study intensity variations, as measured by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), in a solar coronal arcade using a newly developed analysis procedure that employs spatio-temporal auto-correlations. We test our new procedure by studying large-amplitude oscillations excited by nearby flaring activity within a complex arcade and detect a dominant periodicity of 12.5 minutes. We compute this period in two ways: from the traditional time-distance fitting method and using our new auto-correlation procedure. The two analyses yield consistent results. The auto-correlation procedure is then implemented on time series for which the traditional method would fail due to the complexity of overlapping loops and a poor contrast between the loops and the background. Using this new procedure, we discover the presence of small-amplitude oscillations within the same arcade with 8-minute and 10-minute periods prior and subsequent to the large-amplitude oscillations, respectively. Consequently, we identify these as "decayless" oscillations that have only been previously observed in non-flaring loop systems.