Relationship between wave processes in sunspots and quasi-periodic pulsations in active region flares

¹ Institute of Solar-Terrestrial Physics, Lermontov str., 126a, 664033 Irkutsk, Russia e-mail: [sych;anfinogentov]@iszf.irk.ru
² Physics Department, University of Warwick, Coventry, CV4 7AL, UK e-mail: V.Nakariakov@warwick.ac.uk
³ Astronomical Institute of the Academy of Sciences of the Czech Republic, 25165 Onrejov, Czech Republic e-mail: karlicky@asu.cas.cz

Received: 23 March 2009
Accepted: 17 June 2009

Abstract

A phenomenological relationship between oscillations in a sunspot and quasi-periodic pulsations (QPP) in flaring energy releases at an active region (AR) above the sunspot is established. The analysis of the microwave emission recorded by the Nobeyama Radioheliograph at 17 GHz shows a gradual increase in the power of the 3-min oscillation train in the sunspot associated with AR 10756 before flares in this AR. The flaring light curves are found to be bursty with a period of 3 min. Our analysis of the spatial distribution of the 3-min oscillation power implies that the oscillations follow from sunspots along coronal loops towards the flaring site. It is proposed that QPP in the flaring energy releases can be triggered by 3-min slow magnetoacoustic waves leaking from sunspots.