# Observation of a Short Period Quasi-Periodic Pulsation in Solar X-ray, Microwave and EUV Emissions

## TL;DR

This study analyzes a 13-second quasi-periodic pulsation observed across X-ray, microwave, and EUV emissions during a solar flare, linking it to loop interactions and oscillations in the active region.

## Contribution

It provides a multi-wavelength analysis of QPP in a solar flare, suggesting loop interactions and sausage oscillations as possible mechanisms for the pulsations.

## Key findings

- QPP observed in X-ray, microwave, and EUV emissions.
- Loop interactions and oscillations are linked to QPP generation.
- A cool jet and narrow CME were associated with the event.

## Abstract

This paper presents the multi-wavelength analysis of a 13 s quasi-periodic pulsation (QPP) observed in hard X-ray (12-300 keV) and microwave (4.9-34 GHz) emissions during a C-class flare occurred on 21 September 2015. AIA 304 and 171 \AA~ images show an emerging loop/flux tube (L1) moving radially outward, which interacts with preexisting structures within the active region. The QPP was observed during the expansion and rising motion of L1. The Nobeyama Radioheliograph (NoRH) microwave images in 17/34 GHz channels reveal a single radio source, which was co-spatial with a neighboring loop (L2). In addition, using AIA 304 \AA~ images, we detected intensity oscillations in the legs of loop L2 with a period of about 26 s. A similar oscillation period was observed in the GOES soft X-ray flux derivative. This oscillation period seems to increase with time. We suggest that the observed QPP is most likely generated by the interaction between loops L2 and L3 observed in the AIA hot channels (131 and 94 \AA). The merging speed of loops L2 and L3 was ~35 km/s. Loop L1 destroyed possibly by its interaction with preexisting structures in the active region and produced a cool jet with the speed ~106-118 km/s associated with a narrow CME (~770 km/s). Another mechanism of the QPP in terms of a sausage oscillation of the loop (L2) is also possible.