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1.
Yoshimori  M.  Takahashi  K.  Wada  M.  Kusunose  M.  Kondo  I. 《Solar physics》1987,113(1-2):319-325
Solar Physics - Possible solar neutron emission associated with five SMM gamma-ray events on 7 June 1980, 21 June 1980, 6 November 1980, 26 November 1982 and 25 April 1984 was found from analysis...  相似文献   

2.
The SONG instrument onboard the CORONAS-F satellite recorded gamma-ray emission with energy above 500 keV in 28 solar flares over three years of its in-orbit operation. According to the GOES classification, the X-ray importance of these flares lay within the range M1.4-X28. The gamma-ray energy recorded by SONG exceeded 4 MeV in 16 flares. Gamma-ray emission with energy up to 100 MeV was recorded in three events, more specifically, on August 25, 2001, October 28, 2003, and November 4, 2003. Increases in the count rate in the SONG channels that recorded neutrons with energies above 20 MeV were found during these three events. The energies of the recorded neutrons were estimated for the neutron increases. The time dependence of the neutron increases was compared with data from high-altitude ground-based neutron monitors that could, in principle, record the arrival of high-energy neutrons from the Sun. It should be noted that we detected series of flares with gamma-ray emission generated by the same active region (AR). The series in the last decade of August 2002 (AR NOAA 0069), the end of May 2003 (AR NOAA 0365), and the famous period of extreme solar activity in October–November 2003 associated with AR NOAA 0486 and AR NOAA 0501 are quite revealing. The catalog can be of use for future statistical and correlation analyses of solar flares.  相似文献   

3.
We discuss a possible generation of radio bursts preceding final stages of binary neutron star mergings which can be accompanied by short gamma-ray bursts. Detection of such bursts appear to be advantageous in the low-frequency radio band due to a time delay of ten to several hundred seconds required for radio signal to propagate in the ionized intergalactic medium. This delay makes it possible to use short gamma-ray burst alerts to promptly monitor specific regions on the sky by low-frequency radio facilities, especially by LOFAR. To estimate the strength of the radio signal, we assume a power-law dependence of the radio luminosity on the total energy release in a magnetically dominated outflow, as found in millisecond pulsars. Based on the planned LOFAR sensitivity at 120 MHz, we estimate that the LOFAR detection rate of such radio transients could be about several events per month from redshifts up to z∼1.3 in the most optimistic scenario. The LOFAR ability to detect such events would crucially depend on exact efficiency of low-frequency radio emission mechanism.  相似文献   

4.
Lockwood  J.A.  Debrunner  H.  Flueckiger  E.O.  Ryan  J.M. 《Solar physics》2002,208(1):113-140
We have deduced the power-law rigidity spectra, J(P)=AP –, and the spectral evolution of the solar flare events that occurred in the present solar activity cycle on 6 November 1997, 14 July 2000, and 15 and 18 April 2001. The implications of these results for the acceleration of high-energy protons are discussed. The analysis is based on the ratios of the Mt. Washington to the Durham neutron monitor count-rate increases during the solar flare events. These two neutron monitors are located at different elevations (828 and 1030 g cm–2, respectively) but at approximately the same geographical latitude and longitude. The proton spectra from 1 to 10 GV determined from the ratios of the count rate increases of the two neutron monitors are found to agree with those deduced from the global neutron monitor network or selected neutron monitors in 10 solar flare events from 1960 to 1990 for which comparative results are available. Thus the ratio method is quick, easy and reliable for deducing the spectral shape of solar flare protons at neutron monitor rigidities and for obtaining the spectral evolution as a function of time.  相似文献   

5.
GRB 170817A was confirmed to be associated with GW170817, which was produced by a neutron star - neutron star merger. It indicates that at least some short gamma-ray bursts come from binary neutron star mergers. Theoretically, it is widely accepted that short gamma-ray bursts can be produced by two distinctly different mechanisms, binary neutron star mergers and neutron star - black hole mergers. These two kinds of bursts should be different observationally due to their different trigger mechanisms. Motivated by this idea, we collect a universal data set constituted of 51 short gamma-ray bursts observed by Swift/BAT, among which 14 events have extended emission component. We study the observational features of these 51 events statistically. It is found that our samples consist of two distinct groups. They clearly show a bimodal distribution when their peak photon fluxes at 15–150 keV band are plotted against the corresponding fluences. Most interestingly, all the 14 short bursts with extended emission lie in a particular region of this plot. When the fluences are plotted against the burst durations, short bursts with extended emission again tend to concentrate in the long duration segment. These features strongly indicate that short gamma-ray bursts really may come from two distinct types of progenitors. We argue that those short gamma-ray bursts with extended emission come from the coalescence of neutron stars, while the short gamma-ray bursts without extended emission come from neutron star - black hole mergers.  相似文献   

6.
The first increase in neutron monitor count rate during the ground-level event on 24 May 1990 was interpreted by Shea et al. (1991) as a consequence of an arrival of flare neutrons. Debrunner et al. (1991) rejected the neutron hypothesis and proposed that the first neutron monitor increase was due to the arrival of primary protons. We have show that neutron monitor data do not contradict the hypothesis of a neutron origin of the first increase of ground-level event on 24 May 1990.  相似文献   

7.
Usoskin  I.G.  Alanko  K.  Mursula  K.  Kovaltsov  G.A. 《Solar physics》2002,207(2):389-399
Using a stochastic simulation of a one-dimensional heliosphere we calculate galactic cosmic ray spectra at the Earth's orbit for different values of the heliospheric modulation strength . Convoluting these spectra with the specific yield function of a neutron monitor, we obtain the expected neutron monitor count rates for different values of . Finally, inverting this relation, we calculate the modulation strength using the actually recorded neutron monitor count rates. We present the reconstructed annual heliospheric modulation strengths for the neutron monitor era (1953–2000) using several neutron monitors from different latitudes, covering a large range of geomagnetic rigidity cutoffs from polar to equatorial regions. The estimated modulation strengths are shown to be in good agreement with the corresponding estimates reported earlier for some years.  相似文献   

8.
During two extreme bursts of solar activity in March–April 2001 and October–November 2003, the ground-based neutron monitor network recorded a series of outstanding events distinguished by their magnitude and unusual peculiarities. The important changes that lead to increased activity initiated not with the sunspot appearance, but with the large-scale solar magnetic field reconfiguration. A series of strong and moderate magnetic storms and powerful proton events (including ground-level enhancements, GLE) were registered during these periods. The largest and most productive in the 23rd solar cycle, active region 486, generated a significant series of solar flares among which the 4 November 2003 flare (X28/3B) was the most powerful X-ray solar event ever observed. The fastest arrival of the interplanetary disturbance from the Sun (after August 1972) and the highest solar wind velocity and IMF intensity were recorded during these events. Within 1 week, three GLEs of solar cosmic rays were registered by the neutron monitor network (28 and 29 October and 2 November 2003). In this work, we perform a tentative analysis of a number of the effects seen in cosmic rays during these two periods, using the neutron monitor network and other relevant data.  相似文献   

9.
Interactions among a neutron star’s superfluid neutrons, superconducting protons, and solid crust cause predictable spin-down and spin-up driven crustal motion and magnetic field changes. Applications and unsolved problems are discussed for millisecond pulsar evolution and properties, glitches and post-glitch responses, and transcient gamma-ray emission.  相似文献   

10.
Geomagnetic disturbances are the results of interplanetary causes such as high-speed streamers (HSSs), interplanetary coronal mass ejections (ICMEs), corotating interaction regions (CIRs), and magnetic clouds. During different forms of geomagnetic disturbances, we observed changes in the count rate at neutron monitors that are kept at various locations. We studied the count rates measured by neutron monitors at four stations at various latitudes during different categories of geomagnetic events and compared them. We analysed five events: a geomagnetically quiet event, a non-storm high-intensity long-duration continuous AE activity (HILDCAA) event, a storm-preceded HILDCAA event, a geomagnetic substorm event, and a geomagnetic moderate storm event. We based our analysis on geomagnetic indices, solar wind parameters, and interplanetary magnetic field (IMF) parameters. We found that the strength of the modulation was least during the quiet event and highest during the storm-preceded HILDCAA. By analysing the cause of these geomagnetic disturbances, we related each decrease in the neutron monitor data with the corresponding solar cause. For the ICME-driven storm, we observed a decrease in neutron monitor data ranging from 6% to 12% in all stations. On the other hand, we observed a decrease ranging from 2% to 5% for the HSS-driven storm. For the non-storm HILDCAA, we observed a decrease in neutron monitor data of about 1% to 1.5%. For the quiet event, the neutron monitor data fluctuated such that there was no overall decrease in all stations.  相似文献   

11.

The results of observations of the gravitational-wave (GW) event S190425z recorded by the LIGO/Virgo detectors with the anti-coincidence shield (ACS) of the SPI gamma-ray spectrometer onboard the INTEGRAL observatory are presented. With a high probability (>99%) it was associated with a neutron star (NS) merger in a close binary system. This is only the second event of such a type in the history of gravitational-wave observations (after GW170817). A weak gamma-ray burst, GRB190425, consisting of two pulses ～0.5 and ～5.9 s after the NS merger in the event S190425z with an a priori significance of 3.5 and 4.4σ (taken together 5.5σ) was detected by SPI-ACS. Analysis of the SPI-ACS count rate history recorded on these days (a total of ～125 ks of observations) has shown that the rate of random occurrence of two close spikes with the characteristics of GRB190425 does not exceed 6.4 × 10?5 s?1 (i.e., such events occur by chance, on average, every ～4.3 hours). Note that the time profile of GRB190425 has much in common with the profile of GRB170817A accompanying the event GW170817, that both NS mergers were the nearest (≤150 Mpc) of all the events recorded by the LIGO/Virgo detectors, and that no significant excesses of the gamma-ray flux above the background were detected in any of ～30 black hole merger events recorded to date by these detectors. No bursts of hard radiation were detected in the field of view of the SPI and IBIS/ISGRI gamma-ray telescopes onboard INTEGRAL. This, along with the absence of detection of gamma-ray emission from GRB190425 by the GBM gamma-ray burst monitor of the Fermi observatory suggesting its occultation by the Earth, allows the localization region for the source of this GWevent to be reduced significantly. The parameters Eiso and Ep for GRB190425 are estimated and compared with those for GRB170817A.

  相似文献   

12.
During February, 1981 and June, 1982 the gamma-ray and the hard X-ray spectrometers on the Hinotori satellite observed four gamma-ray bursts on 28 February, 21 July, 1981, 26 February and 13 March, 1982. These gamma-ray bursts were simultaneously observed by other satellites. The time histories and energy spectra are shown for these gamma-ray bursts, and the burst sizes (erg cm–2) are estimated. Two possible source locations for the burst of 21 July, 1981 are roughly determined from arrival time delays between two pairs of satellites, PVO-Hinotori and ISEE-3-Hinotori. The weak gamma-ray line peak structure around 1.8 MeV was observed for the burst of 13 March, 1982. The line could be interpreted in terms of gravitationally redshifted neutron capture line at 2.22 MeV.  相似文献   

13.
The depth dependence of the production of neutrons and capture gamma-ray line emission are calculated by Monte Carlo simulation of the nuclear processes taking place when flare-accelerated ions interact with the solar atmosphere. The calculations also give the heliocentric-angular dependence of the 2.223 MeV neutron capture line emission as a function of accelerated-ion energy spectrum and angular distribution. These results are compared with observations to determine the energy spectrum shape and total ion number for various flares.  相似文献   

14.
The Sun is an effective particle accelerator that produces solar energetic particle (SEP) events, during which particles of up to several GeVs can be observed. These events, when they are observed at Earth with the neutron monitor network, are called ground-level enhancements (GLEs). Although these events with their high-energy component have been investigated for several decades, a clear relation between the spectral shape of the SEPs outside the Earth’s magnetosphere and the increase in neutron monitor count rate has yet to be established. Hence, an analysis of these events is of interest for the space weather and for the solar event community.In this article, SEP events with protons accelerated to above 500 MeV were identified using data obtained with the Electron Proton Helium Instrument (EPHIN) onboard the Solar and Heliospheric Observatory (SOHO) between 1995 and 2015. For a statistical analysis, onset times were determined for the events and the proton energy spectra were derived and fitted with a power law.As a result, we present a list of 42 SEP events with protons accelerated to above 500 MeV measured with the EPHIN instrument onboard SOHO. The statistical analysis based on the fitted spectral slopes and absolute intensities is discussed, with special emphasis on whether an event has been observed as a GLE. Furthermore, we are able to determine that the derived intensity at 500 MeV and the observed increase in neutron monitor count rate are correlated for a subset of events.  相似文献   

15.
The three-satellite SIGNE network has observed 26 confirmed gamma-ray bursts in the period September 1978–June 1979. Burst time histories may be used to define several classes of events, with a strong resemblance between events in a given class, but different arrival directions. The spectra of two gamma-ray bursts have been found to evolve from shapes which turn over at low energy during the start of the event, to near power law spectra at the end of the event.Paper presented at the Symposium on Cosmic Gamma-Ray Bursts held at Toulouse, France, 26–29 November, 1979.  相似文献   

16.
Possible phase transitions in neutron star matter, particularly the melting of neutron stars' crystalline cores, are discussed. Such processes may explain the observed luminosity of pulsars. They are used also as a basis for an explanation of the origin of low energy gamma-ray bursts which have been intensively studied for the last few years. The authors discuss the structure of gamma-ray bursts and the possibility of obtaining from observational data some information on thermal evolution of neutron stars and dynamic processes in the pulsar crust.  相似文献   

17.
The remnant resulting from the merger of two neutron stars produces neutrinos in copious amounts. In this paper we present the neutrino emission results obtained via Newtonian, high-resolution simulations of the coalescence event. These simulations use three-dimensional smoothed particle hydrodynamics together with a nuclear, temperature-dependent equation of state and a multiflavour neutrino leakage scheme. We present the details of our scheme, discuss the neutrino emission results from a neutron star coalescence and compare them with the core-collapse supernova case where neutrino emission has been studied for several decades. The average neutrino energies are similar to those in the supernova case, but contrary to the latter, the luminosities are dominated by electron-type antineutrinos that are produced in the hot, neutron-rich, thick disc of the merger remnant. The cooler parts of this disc contain substantial fractions of heavy nuclei, which, however, do not influence the overall neutrino emission results significantly. Our total neutrino luminosities from the merger event are considerably lower than those found in previous investigations. This imposes constraints on the ability of neutron star mergers to produce a gamma-ray burst via neutrino annihilation. The neutrinos are emitted preferentially along the initial binary rotation axis, an event seen 'pole-on' would appear much brighter in neutrinos than a similar event seen 'edge-on'.  相似文献   

18.
Summary. As of today, seven X-ray sources have been tentatively identified as radio-quiet, isolated neutron stars. The family appears to be a rapidly growing one, although not all the objects have been identified with the same degree of certainty. The most convincing example of radio quiet pulsar is certainly Geminga, the neutron star nature of which, proposed in 1983 on the basis of its similarity with the Vela pulsar, has been firmly established with the discovery of its X and pulsation. Four more neutron star candidates, originally found in the Einstein data, have been confirmed by ROSAT, which has added to the list two more entries. All this is not the result of an unbiased search. The seven sources were not selected at random: four are inside supernova remnants, an obvious place to search for isolated neutron stars, while the remaining three were singled out because of some peculiarity. Intense -ray emission in the case of Geminga, very high X-ray counting rate for RXJ185635-3754, or being the brightest unidentified source in the Einstein medium sensitivity survey, MS 0317-6647. In spite of the limited number of objects and of the observational biases, these seven radio quiet neutron star candidates add valuable pieces of information to the observational panorama of known pulsars. Their properties, inferred from the X-ray emission, offer a coherent picture, pointing towards thermally emitting, cooling neutron stars. Received: April 1, 1996  相似文献   

19.
The current Cherenkov telescopes together with GLAST are opening up a new window into the physics at work close to black holes and rapidly rotating neutron stars with great breakthrough potential. Very high energy gamma-ray emission up to 10 TeV is now established in several binaries. The radiative output of gamma-ray binaries is in fact dominated by emission above 1–10 MeV. Most are likely powered by the rotational spindown of a young neutron star that generates a highly relativistic wind. The interaction of this pulsar wind with the companion’s stellar wind is responsible for the high energy gamma-ray emission. There are hints that microquasars, accretion-powered binaries emitting relativistic jets, also emit gamma-ray flares that may be linked to the accretion–ejection process. Studying high energy gamma-ray emission from binaries offers good prospects for the study of pulsar winds physics and may bring new insights into the link between accretion and ejection close to black holes.  相似文献   

20.
S. O. Ifedili 《Solar physics》1996,168(1):195-203
The Forbush decrease in the cosmic radiation has been measured by a charged-particle monitor (E p )> 50 MeV) on board the OGO-6 satellite. For the events of June 7–10, September 27–30, and November 21–December 6, 1969, the Forbush decrease totalled 4.6, 6, and 6% in amplitude, respectively, for the Mt. Washington neutron monitor (P c = 1.24 GV), and 5.2, 13, and 16%, respectively, for the OGO-6 charged-particle monitor in the polar region (P c < 0.3 GB). The depression in the OGO-6 charged-particle monitor was larger at higher geomagnetic latitudes than at lower latitudes. However, for the events of June 7–10 and November 21–December 6, 1969, the Forbush decrease totalled 20 and 15% in amplitude respectively for the Pioneer 8 cosmic-ray telescope (P c > 0.4 GV), which was at the respective distances of 1.08 AU and 1 AU from the Sun. These results indicate that the Forbush decrease has greater effects on lower-energy charged particles, the magnitude of the effect also depending on the location of the detector with respect to the modulating region.The spacecraft data near Earth also showed that, for vertical cut-off rigidities P c 1.8 GV, the total percentage decrease in the amplitudes of the Forbush decreases can be represented by –mP c + k, where m and k are each constant for the particular Forbush decrease but which increase with increasing Mt. Washington neutron monitor monthly average rates, an indication of a flattening of the rigidity dependence of Forbush decreases towards maximum solar modulation.  相似文献   

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