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The observational diversity of optical emission, which coincides with prompt gamma-ray bursts (GRBs), has been discovered in the recent Swift era. We show that on the assumption of the synchrotron radiation for the observed energy range…

Astrophysics · Physics 2009-11-13 Hirotsugu Doi , Kentaro Takami , Ryo Yamazaki

We propose a new method for the classification of optically dark gamma-ray bursts (GRBs), based on the X-ray and optical-to-X-ray spectral indices of GRB afterglows, and utilizing the spectral capabilities of Swift. This method depends less…

High Energy Astrophysical Phenomena · Physics 2010-03-19 A. J. van der Horst , C. Kouveliotou , N. Gehrels , E. Rol , R. A. M. J. Wijers , J. K. Cannizzo , J. Racusin , D. N. Burrows

There is no consensus on the emission mechanism of $\gamma$-ray bursts (GRBs). A synchrotron model can produce $\gamma$-ray spectra with the empirical Band function form, from a piece-wise two-power-law electron energy distribution (2EPLS).…

High Energy Astrophysical Phenomena · Physics 2019-09-06 Bruce Grossan , Pawan Kumar , George F. Smoot

We calculate the synchrotron self-Compton emission from internal shocks occurring in relativistic winds as a source of gamma-ray bursts, with allowance for self-absorption. For plausible model parameters most pulses within a Gamma-Ray Burst…

Astrophysics · Physics 2009-10-31 A. Panaitescu , P. Meszaros

We discuss how gamma-ray burst (GRB) optical afterglows and multiwavelength observations of their host galaxies can be used to obtain information about the relative amounts of star formation happening in optical and submillimetre galaxies.…

Astrophysics · Physics 2009-11-07 Neil Trentham , Enrico Ramirez-Ruiz , A. W. Blain

The origin of prompt emission from gamma ray bursts remains to be an open question. Correlated prompt optical and gamma-ray emission observed in a handful of GRBs strongly suggests a common emission region, but failure to adequately fit the…

High Energy Astrophysical Phenomena · Physics 2016-12-21 S. Guiriec , C. Kouveliotou , D. H. Hartmann , J. Granot , K. Asano , P. Meszaros , R. Gill , N. Gehrels , J. McEnery

It has been proposed that the temporal coincidence of a gamma-ray burst (GRB) and a type Ib/c supernova (SN) can be explained with the concept of induced gravitational collapse (IGC), induced by the matter ejected from an SN Ib/c accreting…

Taking into account the recent suggestion that a short gamma-ray burst (GRB) looks like the first 1 sec of a long GRB, we propose that the jet of a GRB consists of multiple sub-jets or sub-shells (i.e., an inhomogeneous jet model). The…

Astrophysics · Physics 2009-11-10 Ryo Yamazaki , Kunihito Ioka , Takashi Nakamura

The emission mechanism of the gamma-ray bursts (GRBs) is still a matter of debates. The standard synchrotron energy spectrum of cooling electrons F_E ~ E^{-1/2} is much too soft to account for the majority of the observed spectral slopes.…

Astrophysics · Physics 2009-11-10 Boris E. Stern , Juri Poutanen

The cumulative light curves of a large sample of gamma-ray bursts (GRBs) were obtained by summing the BATSE counts. The smoothed profiles are much simpler than the complex and erratic running light curves that are normally used. For most…

Astrophysics · Physics 2009-11-07 S. McBreen , B. McBreen , L. Hanlon , F. Quilligan

Gamma-ray bursts (GRBs) are brief but intense emission of soft $\gamma-$rays, mostly lasting from a few seconds to a few thousand seconds. For such kind of high energy transients, their isotropic-equivalent-energy ($E_{\rm iso}$) function…

High Energy Astrophysical Phenomena · Physics 2014-07-18 Shi-Wei Wu , Dong Xu , Fu-Wen Zhang , Da-Ming Wei

In this paper we give a brief review of our recent studies on the long and short gamma-ray bursts (GRBs) detected Swift, in an effort to understand the puzzle of classifying GRBs. We consider that it is still an appealing conjecture that…

High Energy Astrophysical Phenomena · Physics 2014-01-29 Lang Shao , Fu-Wen Zhang , Zi-Gao Dai , Zhi-Ping Jin , Jing-Zhi Yan , Da-Ming Wei

Gamma ray bursts (GRBs) are short and intense pulses of $\gamma$-rays arriving from random directions in the sky. Several years ago Amelino-Camelia et al. pointed out that a comparison of time of arrival of photons at different energies…

Astrophysics · Physics 2009-11-10 Tsvi Piran

Gamma Ray Bursts (GRBs) show evidence of different light curves, duration, afterglows, host galaxies and they explode within a wide redshift range. However, their spectral energy distributions (SEDs) appear to be very similar showing a…

High Energy Astrophysical Phenomena · Physics 2015-05-27 F. Massaro , J. E. Grindlay

A gravitationally lensed gamma-ray burst (GRB) would appear as multiple bursts with identical light curves, separated in time and differing only by the scaling of their amplitudes. However, noise may make them difficult to identify as…

Astrophysics · Physics 2009-10-22 M. A. Nowak , S. A. Grossman

We propose a possible unified model of short and long gamma-ray bursts (GRBs), X-ray rich GRBs, and X-ray flashes. The jet of a GRB is assumed to consist of multiple sub-jets or sub-shells (i.e., an inhomogeneous jet model). The…

Astrophysics · Physics 2010-11-11 Ryo Yamazaki , Kunihito Ioka , Takashi Nakamura , Kenji Toma

A possible unified model of short and long gamma-ray bursts (GRBs), X-ray rich GRBs, and X-ray flashes is proposed. It is assumed that the jet of a GRB consists of many emitting sub-shells (i.e., an inhomogeneous jet model). The…

Astrophysics · Physics 2007-05-23 Ryo Yamazaki , Kunihito Ioka , Takashi Nakamura , Kenji Toma

We present an optical flux vs. X-ray flux diagram for all known gamma-ray bursts (GRBs) for which an X-ray afterglow has been detected. We propose an operational definition of dark bursts as those bursts that are optically subluminous with…

Astrophysics · Physics 2007-05-23 P. Jakobsson , J. Hjorth , J. P. U. Fynbo , D. Watson , K. Pedersen , G. Bjornsson , J. Gorosabel

We present a new technique to calculate the spectral lags of gamma-ray bursts (GRBs). Unlike previous processing methods, we first smooth the light curves of gamma-ray bursts in high and low energy bands using the "Loess" filter, then, we…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Zhao-sheng Li , Li Chen , De-hua Wang

We present an analysis of early BAT and XRT data for 107 gamma--ray bursts (GRBs) observed by the Swift satellite. We use these data to examine the behaviour of the X-ray light curve and propose a classification scheme for GRBs based on…

Astrophysics · Physics 2008-11-26 P. T. O'Brien , R. Willingale
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