Pulsations in solar flares matching observations and models

Pulsations in solar flares: matching observations and models The first (of two) Team Meeting at ISSI-BJ, 16 -20 October, 2017 ISSI-BJ International Team led by Dr. Ivan Zimovets & Prof. Zongjun Ning The Team focuses on comprehensive analysis of solar flare space- and ground-based observations and advanced modeling to deepen current knowledge about non-stationary processes of flare energy release manifested as pulsations (or quasi-periodic pulsations - QPP) of flare electromagnetic emission. The Team is composed of international experts in the relevant areas of solar physics and is aiming to: Team Website - develop more rigorous criteria of quasi-periodicity for solar flare light curves; - utilize new methods of analysis of nonlinear and non-stationary datasets; - develop an advanced classification of different types of pulsations in solar flares; - perform detailed multi-wavelength spatially-resolved analysis of the sources of pulsations in the large sample of solar flares using modern observational datasets (RHESSI, Fermi, SDO, IRIS, GOES, Lomonosov, Vernov, No. RH/No. RP, SSRT, etc. ); - assess adequacy and improve the existent flare models; - evaluate the possible role of pulsations in solar-terrestrial connections; - develop a strategy of exploration of pulsations in solar and stellar flares with space- and ground-based instruments in the coming years.

List of Team Meeting-1 attendees No Team Member Country Affiliation Email 1 AFANASYEV Andrei* Russia ISTP SB RAS afa@iszf. irk. ru 2 CHEN Peng-Fei* China School of Astronomy & Space Science, Nanjing University chenpf@nju. edu. cn 3 GAO Guannan* China Yunnan Observatories CAS ggn@ynao. ac. cn 4 HE Han**** China NAO CAS 5 HUANG Jing**** China NAO CAS huangj@nao. cas. cn 6 7 INGLIS Andrew* KARLICKY Marian* USA CR NASA GSFC andrew. inglis@nasa. gov Astronomical Institute, Academy karlicky@asu. cas. cz of Sciences of the Czech Republic 8 9 10 KOLOTKOV Dmitrii** KUMAR Pankaj* LI Bo* UK USA China D. Kolotkov@warwick. ac. uk ptomar 2006@gmail. com bbl@sdu. edu. cn 11 12 13 14 LI Dong*** NAKARIAKOV Valery* NING Zongjun* NISHIZUKA Naoto* China UK China Japan University of Warwick NASA GSFC School of Space Science and Physics, Shandong University PMO CAS University of Warwick PMO CAS National Institute of Information and Communications Technology 15 SRIVASTAVA Abhishek Kumar* Indian Institute of Technology (BHU) asrivastava. app@iitbhu. ac. in 16 17 SU Wei* TAKASOA Shinsuke* China Japan PMO CAS Laboratory for Theoretical Astronomy & Astrophysics, Department of Physics, Nagoya University carlosuxyz@163. com takasao@nagoya-u. jp 18 19 20 TAN Baolin* HUI Tian* YUAN Ding* China bltan@nao. cas. cn huitian@pku. edu. cn yuanding@hit. edu. cn 21 22 ZHAO Xiaozhou** ZIMOVETS Ivan* China Russia, China NAO CAS Peking University Harbin Institute of Technology, Shenzhen PMO CAS IKI RAS, NSSC CAS, ISSI-BJ lidong@pmo. ac. cn v. nakariakov@warwick. ac. uk ningzongjun@pmo. ac. cn nishizuka. naoto@nict. go. jp zhaoxz@pmo. ac. cn ivanzim@iki. rssi. ru * Official Team Member ** Official Young Scientist *** Non-official member with presentation **** Non-official member – listener, without presentation Team Statistics: Team Meeting-1 Statistics: • 19 official Team members (including 2 young scientists & 3 self-paid members from Beijing) • 19 attendees (including 16 official Team members & 2 young scientists) • Representatives of 6 countries (CN, RU, IN, JP, US, GB) • 25 Talks (including 2 given by Skype) • 50%/ 50% observations/theory

Main achievements and follow-on perspectives: • All Meeting attendees expressed the opinion that the Meeting-1 was successful, both in terms of organization and in terms of science. • Talks were given and discussions were held on all major issues related to the problem of quasi-periodic pulsations (QPPs) in solar flares (see p. 1). • The main current questions on flare QPPs were summarized and the possible ways to answer them were outlined, including several particular tasks to be solved between Meeting-1 and Meeting-2 (see p. 4). • Several collaborative researches by small groups (of 2 -5 team members) were initiated. • Possible joint publication, grant and position application activities were discussed. • Possibility to organize a Workshop (in 2019) devoted to the 50 th anniversary of the QPPs discovery in solar flares was discussed • Time slots for Meeting-2 were discussed (probably, October 2018).

Main tasks to be addressed between Team Meeting-1 & -2 [by groups] 1) Further development/exploitation of a mathematical apparatus for identification of pulsations in flare light curves [D. Kolotkov, A. Inglis, V. Nakariakov, I. Zimovets] 2) The nature of power law shape of Fourier spectra of flare light curves (physical or mathematical effect? the “trend effect”; fractal reconnection signature; etc. ) [N. Nishizuka, D. Kolotkov, I. Zimovets, M. Karlicky] 3) Participation in analysis of artificial flare light curves generated by A. -M. Broomhall for determination of the most effective methods for finding QPPs of various types [D. Kolotkov, A. Inglis, V. Nakariakov, I. Zimovets, A. Srivastava] 4) Design of the QPPs “model-property matrix” (preparation of a guidance how to choose an adequate model for QPPs possessing a set of observable properties) [D. Kolotkov, I. Zimovets, V. Nakariakov, A. Inglis] 5) The origin of pre-flare soft X-ray QPPs (e. g. , LRC-circuit model, filament oscillations; need detailed spatially-resolved observations, e. g. with AIA/SDO, HMI/SDO and RHESSI) [B. Tan, P. -F. Chen, D. Kolotkov, I. Zimovets] 6) The origin of “ 1 -min” X-ray QPPs (real or instrumental? ) [Z. Ning, A. Inglis, I. Zimovets] 7) Further modeling of 2 D effects, which can be responsible for QPPs during a flux rope eruption and magnetic reconnection (oscillating eruption, unsteady/“bursty”/fractal regimes of magnetic reconnection, “above-the-loop-top” oscillations) [S. Takasao, N. Nishizuka, X. Zhao, M. Karlicky] 8) 3 D flare modeling (incorporation of flare dynamics in the 3 rd direction, i. e. along an MPIL) for the QPP-problem (what is an along-MPIL trigger? what does determine its speed, characteristic spatial and temporal scales of flaring loops stacked into arcades? ) [S. Takasao, N. Nishizuka, X. Zhao, M. Karlicky, I. Zimovets] 9) The role of fast and slow mode waves in flare QPPs [D. Yuan, Li B. , A. Afanasyev, V. Nakariakov] 10) Exploration of the IRIS flare data base for the QPP searching [H. Tian, Z. Ning, Li D. ] 11) Searching for physical differences between flares with/without pulsations [I. Zimovets, P. Kumar] 12) Expansion of the large-scale search for flare QPPs (by different techniques) and correlative analysis of QPPs’ and parent flare regions’ properties [A. Inglis, I. Zimovets, Z. Ning, V. Nakariakov]