Giant flares in soft γ -ray repeaters and short GRBs

2007 ◽  
Vol 365 (1854) ◽  
pp. 1307-1313 ◽  
Author(s):  
S Zane
Keyword(s):  
Neutron Stars ◽  
Energy Release ◽  
Gamma Ray ◽  
Rare Events ◽  
Gamma Ray Bursts ◽  
Current Scenario ◽  
Γ Ray ◽  
Short Grbs

Soft gamma-ray repeaters (SGRs) are a peculiar family of bursting neutron stars that, occasionally, have been observed to emit extremely energetic giant flares (GFs), with energy release up to approximately 10 47  erg s −1 . These are exceptional and rare events. It has been recently proposed that GFs, if emitted by extragalactic SGRs, may appear at Earth as short gamma-ray bursts. Here, I will discuss the properties of the GFs observed in SGRs, with particular emphasis on the spectacular event registered from SGR 1806-20 in December 2004. I will review the current scenario for the production of the flare, within the magnetar model, and the observational implications.

scholarly journals Astrophysical explosions: from solar flares to cosmic gamma-ray bursts

2012 ◽  
Vol 370 (1960) ◽  
pp. 774-799 ◽  
Author(s):  
J. Craig Wheeler
Keyword(s):  
Neutron Stars ◽  
Energy Release ◽  
Solar Flares ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Accretion Discs ◽  
Stellar Flares ◽  
Crossing Time ◽  
Dynamical Time ◽  
New Research

Astrophysical explosions result from the release of magnetic, gravitational or thermonuclear energy on dynamical time scales, typically the sound-crossing time for the system. These explosions include solar and stellar flares, eruptive phenomena in accretion discs, thermonuclear combustion on the surfaces of white dwarfs and neutron stars, violent magnetic reconnection in neutron stars, thermonuclear and gravitational collapse supernovae and cosmic gamma-ray bursts, each representing a different type and amount of energy release. This paper summarizes the properties of these explosions and describes new research on thermonuclear explosions and explosions in extended circumstellar media. Parallels are drawn between studies of terrestrial and astrophysical explosions, especially the physics of the transition from deflagration-to-detonation.

scholarly journals On the Reclassification of Short GRBs

2012 ◽  
Vol 8 (S290) ◽  
pp. 361-363
Author(s):  
Zhibin Zhang ◽  
Yongfeng Huang ◽  
Hongchao Liu
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Radiation Mechanism ◽  
Duration Time ◽  
Central Engine ◽  
Peak Energy ◽  
Thermal Origin ◽  
Γ Ray ◽  
Short Grbs ◽  
Extended Emission

AbstractBy collecting 17 short gamma-ray bursts with necessary data, we find a correlation of Lp ∝ Ep,i1.7, which is very consistent with that derived from a greatly expanded sample of 148 Swift long gamma-ray bursts. It is argued that the radiation mechanism of both long and short gamma-ray bursts should be similar, i.e., of quasi-thermal origin caused by the photosphere and the dissipation occurring very near the central engine. In addition, we suggest that the Ep,i-Lp relation can be used to identified a burst among normal short bursts, short bursts with extended emission and long bursts with short-hard properties. We also find the ratio of peak energy to fluence in the prompt γ-ray band is a prospective discriminator, similar to the traditional duration time.

scholarly journals Gamma-ray bursts: A brief survey of the diversity

2018 ◽  
Vol 14 (S346) ◽  
pp. 383-387
Author(s):  
Attila Mészáros ◽  
Jakub Řípa
Keyword(s):  
Black Holes ◽  
Neutron Stars ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Statistical Studies ◽  
Short Grbs

AbstractThe separation of the gamma-ray bursts (GRBs) into short/hard and long/soft subclasses, respectively, is well supported both theoretically and observationally. The long ones are coupled to supernovae type Ib/Ic - the short ones are connected to the merging of two neutron stars, where one or even both neutron stars can be substituted by black holes. These short GRBs - as merging binaries - can also serve as the sources of gravitation waves, and are observable as the recently detected macronovae. Since 1998 there are several statistical studies suggesting the existence of more than two subgroups. There can be a subgroup having an intermediate durations; there can be a subgroup with ultra-long durations; the long/soft subgroup itself can be divided into two subclasses with respect to the luminosity of GRBs. The authors with other collaborators provided several statistical studies in this topic. This field of the GRB-diversity is briefly surveyed in this contribution.

scholarly journals Limits on quantum gravity effects from Swift short gamma-ray bursts

2017 ◽  
Vol 607 ◽  
pp. A121 ◽  
Author(s):  
M. G. Bernardini ◽  
G. Ghirlanda ◽  
S. Campana ◽  
P. D’Avanzo ◽  
J.-L. Atteia ◽  
...  
Keyword(s):  
Quantum Gravity ◽  
Gamma Ray ◽  
Lorentz Invariance ◽  
Spectral Energy Distribution ◽  
Gamma Ray Bursts ◽  
Low Energy ◽  
Energy Separation ◽  
Spectral Energy ◽  
Spectral Evolution ◽  
Short Grbs

The delay in arrival times between high and low energy photons from cosmic sources can be used to test the violation of the Lorentz invariance (LIV), predicted by some quantum gravity theories, and to constrain its characteristic energy scale EQG that is of the order of the Planck energy. Gamma-ray bursts (GRBs) and blazars are ideal for this purpose thanks to their broad spectral energy distribution and cosmological distances: at first order approximation, the constraints on EQG are proportional to the photon energy separation and the distance of the source. However, the LIV tiny contribution to the total time delay can be dominated by intrinsic delays related to the physics of the sources: long GRBs typically show a delay between high and low energy photons related to their spectral evolution (spectral lag). Short GRBs have null intrinsic spectral lags and are therefore an ideal tool to measure any LIV effect. We considered a sample of 15 short GRBs with known redshift observed by Swift and we estimate a limit on EQG ≳ 1.5 × 1016 GeV. Our estimate represents an improvement with respect to the limit obtained with a larger (double) sample of long GRBs and is more robust than the estimates on single events because it accounts for the intrinsic delay in a statistical sense.

The melting of neutron stars' crystalline cores and gamma-ray bursts

1976 ◽  
Vol 39 (1) ◽  
pp. 243-249 ◽  
Author(s):  
Ju. M. Bruk ◽  
K. I. Kugel
Keyword(s):  
Neutron Stars ◽  
Gamma Ray ◽  
Gamma Ray Bursts

Gamma-ray bursts from galactic neutron stars?

1989 ◽  
Vol 10 (2) ◽  
pp. 27-37
Author(s):  
D. Hartmann ◽  
R.I. Epstein ◽  
S.E. Woosley
Keyword(s):  
Neutron Stars ◽  
Gamma Ray ◽  
Gamma Ray Bursts

Swift observations of gamma-ray bursts

2007 ◽  
Vol 365 (1854) ◽  
pp. 1119-1128 ◽  
Author(s):  
Neil Gehrels
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Gamma Ray Bursts ◽  
Optical Observations ◽  
Nearby Galaxy ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Other Information ◽  
Short Grbs

Since its launch on 20 November 2004, the Swift mission has been detecting approximately 100 gamma-ray bursts (GRBs) each year, and immediately (within approx. 90 s) starting simultaneous X-ray and UV/optical observations of the afterglow. It has already collected an impressive database, including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows and a rapid follow-up by other observatories notified through the GCN. Advances in our understanding of short GRBs have been spectacular. The detection of X-ray afterglows has led to accurate localizations and the conclusion that short GRBs can occur in non-star-forming galaxies or regions, whereas long GRBs are strongly concentrated within the star-forming regions. This is consistent with the NS merger model. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at z ∼5–6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to a much greater distance than other techniques. The localization of GRB 060218 to a nearby galaxy, and the association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova.

scholarly journals On the delay times of merging double neutron stars

2020 ◽  
Vol 500 (2) ◽  
pp. 1755-1771
Author(s):  
Laura Greggio ◽  
Paolo Simonetti ◽  
Francesca Matteucci
Keyword(s):  
Neutron Stars ◽  
Binary Systems ◽  
Milky Way ◽  
Gamma Ray ◽  
Chemical Properties ◽  
Redshift Distribution ◽  
Strong Constraint ◽  
Delay Times ◽  
Best Fitting ◽  
Short Grbs

ABSTRACT The merging rate of double neutron stars (DNS) has a great impact on many astrophysical issues, including the interpretation of gravitational waves signals, of the short gamma-ray bursts (GRBs), and of the chemical properties of stars in galaxies. Such rate depends on the distribution of the delay times (DDT) of the merging events. In this paper, we derive a theoretical DDT of merging DNS following from the characteristics of the clock controlling their evolution. We show that the shape of the DDT is governed by a few key parameters, primarily the lower limit and the slope of the distribution of the separation of the DNS systems at birth. With a parametric approach, we investigate on the observational constraints on the DDT from the cosmic rate of short GRBs and the europium-to-iron ratio in Milky Way stars, taken as tracer of the products of the explosion. We find that the local rate of DNS merging requires that $\sim \! 1 {{\ \rm per\ cent}}$ of neutron stars progenitors live in binary systems which end their evolution as merging DNS within a Hubble time. The redshift distribution of short GRBs does not yet provide a strong constraint on the shape of the DDT, although the best-fitting models have a shallow DDT. The chemical pattern in Milky Way stars requires an additional source of europium besides the products from merging DNS, which weakens the related requirement on the DDT. At present both constraints can be matched with the same DDT for merging DNS.

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