Multiperiodicity in quasi-periodic pulsations of flare hard X-rays: a case study

TL;DR

This study analyzes a solar flare exhibiting simultaneous quasi-periodic pulsations with two distinct periods, linking them to magnetic structures and reconnection processes, and suggests multiperiodicity may be common in flare hybrids.

Contribution

It provides a detailed case study connecting observed QPPs to magnetic structures and proposes multiperiodicity as a typical feature in interacting magnetic systems during flares.

Findings

Identified two simultaneous periods in hard X-ray pulsations (26-31 s and 110 s).

Linked periods to specific magnetic structures and reconnection events.

Suggested multiperiodicity is common in flare hybrids involving interacting magnetic structures.

Abstract

We present a case study of the solar flare (SOL2001-10-02T17:31) that showed quasi-periodic pulsations (QPPs) in hard X-rays with two simultaneously excited periods, P_1 = 26-31 s and P_2 = 110 s. Complete evolution of the flare recorded by the Yohkoh telescopes, together with the patrol SOHO/EIT images, allowed us to identify magnetic structures responsible for particular periods and to propose an overall scenario which is consistent with the available observations. Namely, we suggest that emerging magnetic flux initiated the reconnection with legs of a large arcade of coronal loops that had been present in an active region for several days. The reconnection excited MHD oscillations in both magnetic structures simultaneously: period P_1 was generated in the emerging loop and in a loop being a result of the reconnection; period P_2 occurred in the arcade. Both resonators produced photons of different spectra. We anticipate that multiperiodicity in hard X-rays can be a common feature of flare hybrids, i.e. the events, in which magnetic structures of different sizes interact.