Universality in solar flare, magnetic storm and earthquake dynamics using Tsallis statistical mechanics

The universal character of the dynamics of various extreme phenomena is an outstanding scientific challenge. We show that X-ray flux and D_st time series during powerful solar flares and intense magnetic storms, respectively, obey a nonextensive energy distribution function for earthquake dynamics with similar values for the Tsallis entropic index q. Thus, evidence for universality in solar flares, magnetic storms and earthquakes arise naturally in the framework of Tsallis statistical mechanics. The observed similarity suggests a common approach to the interpretation of these diverse phenomena in terms of driving physical mechanisms that have the same character.     

Spectra of solar neutrons with energies of ~10–1000 MeV in the PAMELA experiment in the flare events of 2006–2015

The first results from measuring the spectra of solar neutrons with energies of ~10–1000 MeV in the solar flares of 2006–2015 observed by the PAMELA international space experiment are presented. The PAMELA neutron detector with ³He counters and a moderator with an area of 0.18 m² allows us to estimate the flux of solar neutrons during solar flares. Solar neutrons with energies of ~10–1000 MeV likely occurred in 21 out of the 24 analyzed flares of 2006–2015.     

Relativistic SCRs during the events of solar cycle 19

Two major ground-level SCR events in solar cycle 19 are analyzed: the events of May 4 and November 12, 1960. The characteristics of relativistic solar protons (RSPs) have been obtained using the up-to-date method based on the data from the ground based network of neutron monitors. The event of May 4, 1960, occurred against a quiet background, and during the event of 12.11.1960 two shocks, caused by previous flares in the same active region, approached the Earth. The RSP dynamics, related to disturbances in the interplanetary medium, is studied. The solar proton spectra, obtained from the ground-based measurements, are compared to the direct balloon measurements performed at that time.     

Study of dynamics of global disturbances of the Earth’s magnetosphere using muon detectors

Amethod is developed, whichmakes it possible to predict in advance disturbances in the Earth’s magnetosphere, caused by solar flares or changes in the heliospheric magnetic field, since the cosmic particle flux reaches the Earth much earlier than coronal plasma bursts. To scan the celestial hemisphere, wide-aperture muon detectors are used. A unique system of muon hodoscopes was developed at the NEVOD Science and Education Center (MEPhI, Moscow). The data of the URAGAN muon hodoscope on two-dimensional dynamics of the muon flux during the Forbush effect of November 14, 2006 are analyzed. Changes in the muon flux intensity, measured at various directions with an interval of 30 min are shown. The results obtained demonstrate the muon flux sensitivity to solar plasma cloud motion, which offers prospects to use muon detectors to probe interplanetary space at long distances from the Earth and to predict geomagnetic disturbances.     

Solar neutrons and entropy criterion

The start times of solar X-ray flares of class higher than M1, recorded at the GOES satellite, were superimposed on the time series of experimental data obtained at the high-altitude Alma-Ata neutron monitor during 1976–2005. A search for direct solar neutrons by means of the entropy criterion has been performed in the vicinity of the start times of X-ray flares in the monitor data and a statistically significant effect has been found.     

The influence of solar flares on the near-Earth space radiation environment in March and April 2013: Possibilities of operational monitoring

This paper deals with the operational analysis of the influence of solar flares, which produced solar cosmic rays, on the near-Earth radiation environment in space during the period from March 1 to April 18, 2013.     

Study of solar features causing GMSs with 250γ<<Emphasis Type="Italic">H</Emphasis><400γ

The effect of solar features on geospheric conditions leading to geomagnetic storms (GMSs) with planetary index,A ^P ≥ 20 and the range of horizontal component of the Earth’s magnetic fieldH such that 250γ <H < 400γ has been investigated using interplanetary magnetic field (IMF), solar wind plasma (SWP) and solar geophysical data (SGD) during the period 1978–99. Statistically, it is observed that maximum number of GMSs have occurred during the maximum solar activity years of 21st and 22nd solar cycles. A peculiar result has been observed during the years 1982, 1994 when sunspot numbers (SSNs) decrease very rapidly while numbers of GMSs increase. No distinct association between yearly occurrence of disturbed days and SSNs is observed. Maximum number of disturbed days have occurred during spring and rainy seasons showing a seasonal variation of disturbed days. No significant correlation between magnitude (intensity) of GMSs and importance ofH _α , X-ray solar flares has been observed. Maximum number of GMSs is associated with solar flares of lower importance, i.e., SF during the period 1978-93.H _α , X-ray solar flares occurred within lower helio-latitudes, i.e., (0–30)°N to (0–30)°S are associated with GMSs. NoH _α , X-ray solar flares have occurred beyond 40°N or 40°S in association with GMSs. In helio-latitude range (10–40)°N to (10–40)°S, the 89.5% concentration of active prominences and disappearing filaments (APDFs) are associated with GMSs. Maximum number of GMSs are associated with solar flares. Coronal mass ejections (CMEs) are related with eruptive prominences, solar flares, type IV radio burst and they occur at low helio-latitude. It is observed that CMEs related GMS events are not always associated with high speed solar wind streams (HSSWSs). In many individual events, the travel time between the explosion on the Sun and maximum activity lies between 58 and 118 h causing GMSs at the Earth.     

Investigating the characteristics of X-ray flares of a quiet sun using the PINGVIN-M polarimeter aboard the KORONAS-FOTON Satellite

The PINGVIN-M polarimeter was launched into orbit on January 31, 2009, as a part of the equipment of the KORONAS-FOTON Satellite. We discuss the results from recording solar flares using the PINGVIN-M polarimeter in the year 2009. We also consider the statistical characteristics of the recorded B- and C-class solar flares in terms of time, plasma temperature, and volume of emission.     

Solar flare neutrinos

Summary The theory of high-energy neutrinos generation in the solar atmosphere during the flares is developed. A possible effect in different neutrino detectors is discussed.     

Magnetic reconnection and acceleration of particles on the sun

The present-day state of the problem regarding the acceleration of high-energy particles in solar flares is reviewed briefly. It is shown that an analytical solution to the equation of charged-particle motion in a reconnecting current layer with a 3D magnetic field and the electric field caused by magnetic reconnection allows us to offer an explanation for the acceleration of electrons and protons to relativistic energies over very short time intervals. The theoretical results are compared to recent observations of accelerated particles in solar flares.     

Heat-transfer mechanisms in solar flares. 1: Classical and anomalous heat conduction

In the context of the problem of energy transport in solar flares, simplified analytical models have been developed that describe plasma heating in the solar atmosphere by heat fluxes from the super-hot (T _e ≳ 10⁸ K) reconnecting current layer. It is shown that the applicability conditions of common heat conduction produced by Coulomb collisions of electrons in plasma are not fulfilled in solar flares. The heat flux calculated using the classical Fourier’s law proves to be significantly higher than the real energy fluxes known from modern multi-wavelength observations of flares. The so called anomalous flux produced by interaction of free electrons with ion acoustic waves in a plasma is critically analyzed. The question of what the dominant mechanism of heat transfer in solar flares is requires additional consideration [1].     

Solar cosmic rays

Summary This report is a brief overview of the energetic-particle phenomena related to solar activity discussed at the XXIV International Cosmic-Ray Conference. In the rapporteur's opinion, the most significant results to be highlighted are: 1) the new higher-energy measurements of the solar energetic ion charge state which seem to be consistent with the older measurements at ∼1 MeV/nucleon, and 2) the many reports of extended gamma-ray production during solar flares with multiple episodes of emission implying multiple episodes of particle acceleration. Rapporteur talk given at the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Bremsstrahlung of relativistic electrons accelerated in solar flares: The intensity and degree of polarization

The generation of bremsstrahlung by relativistic electrons accelerated in solar flares is considered. The electron distribution function is calculated numerically using the relativistic Fokker-Planck equation. The intensity and degree of polarization of hard X rays are calculated as functions of the energy, observation angle, and electron distributions in pitch angle and energy. The degree of polarization does not exceed 40% and depends most strongly on the observation angle and hardness of the electron energy spectra. The results of model computation are compared with data for solar flares observed July 23, 2002 and October 28, 2003.     

Medium energy neutrinos from solar flares

The production of neutrinos with energies higher than 0.1 GeV in the solar atmosphere during solar flares is discussed. Neutrinos and muons are generated in decays of π^+- mesons produced in nuclear interactions of accelerated solar flare protons with matter of the Sun. Muons themselves decay yielding neutrinos. These neutrinos could come to the Earth and be detected with neutrino telescopes. Estimations of fluxes of such neutrinos are given.     

Detection of solar neutrons by ground-based neutron monitors

Summary The analysis of the Rome NM-64 data, performed on the occasion of 8 solar flares accompanied by gamma-bursts and 10 solar flares accompanied by large X-ray fluxes, shows that the solar energetic neutron events could be detected by ground-based stations particularly when they are located at mountain altitude and middle-low latitudes. Suggestions for improving the neutron monitor efficiency for detecting solar neutron events are given. Paper presented at the 2^o Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May-2 June 1984.     

Search for solar neutrons using the data of neutron detector of the PAMELA spectrometer

The study is devoted to the development of the technique for searching for neutrons of solar origin during solar flares using the neutron detector of the PAMELA magnetic spectrometer onboard the RESURS-DK1 satellite. The study of the neutron detector counting rates showed that it operates properly and background conditions are stable in the geomagnetic equator region. 27 solar events from December 2006 to September 2014 were analyzed. Some events contain indications of solar neutron detection. The final conclusion on the nature of these neutrons requires an increase in statistics; to this end, background conditions in polar regions should be analyzed to increase the observation interval.     

太阳大耀斑期间甚高能粒子流强增加的一种机制

近年来,在太阳大耀班期间,由地面中子记录装置及地下不同深度μ子记录器记录到宇宙线粒子的短期增长(GLE)现象,其能量范围已达几百GeV,甚至可达TeV能区.本文讨论了TeV能区的增长现象可能是银河宇宙线部分粒子获得再加速,由于宇宙线粒子能谱很陡,几百GeV的再加速能量能使TeV以上能区宇宙线流强有明显增长.     

A simple 2D SOC model for one of the main sources of geomagnetic disturbances: Flares

We introduce a simple model for solar flares, one of the main sources of geomagnetic disturbances. We have obtained power-laws for the probability distribution functions of some relevant physical characteristics of flares which could serve as the fingerprint of a critical state at the base of such phenomena and, given that we have not introduced a fine tune mechanism, of self-organized criticality. We compare our results with some recent experimental work on the statistics of flares and analyze the possible connection of these power laws with others already found by our group in geomagnetic disturbances distributions. We also present some limitations of our model as well as possible extensions and corrections to be taken into account in future works.     

Hard X-ray compton polarimetry with the PENGUIN-M instrument in the spaceborne experiment CORONAS-PHOTON

We describe the main parameters of the PENGUIN-MD detector unit of the PENGUIN-M instrument designed to measure the degree of linear polarization of X-ray radiation from solar flares in the energy range 20–150 keV and the X-ray spectra of solar flares in the energy range 2–500 keV. The method for measuring the X-ray polarization employed in the PENGUIN-MD unit is based on registration of coincidences in an active scatterer and scattered-radiation detectors. This method makes it possible to substantially reduce the background and to increase the sensitivity and reliability of the measurements.     

Possibilities of VLBI observation of solar spike-like events

Modern theoretical and experimental investigations of energy release fragmentation in solar flares show the necessity of observations with high space and time resolution. In this paper, we analyze earlier interferometric observations of solar radio spikes and discuss the first results of the Radiophysical Research Institute of Nizhny Novgorod (NIRFI) in this field. We describe the NIRFI's receiving and analyzing equipment, which is part of the measuring complex for solarflare investigation with high space and time resolution and enables one to analyze the form of the interference signal and its amplitude spectrum with time and frequency resolutions of up to 16.7 sec and 100 Hz, respectively. The prospects for VLBI observation of solar flares with high space resolution are discussed.Radiophysical Research Institute, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 10, pp. 1046–1056, October, 1995.