scholarly journals Diverse Features of the Multiwavelength Afterglows of Gamma-Ray Bursts: Natural or Special?

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
J. J. Geng ◽  
Y. F. Huang
Keyword(s):  
Black Holes ◽  
Numerical Method ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Shock Model ◽  
Reverse Shock ◽  
X Ray ◽  
Electron Positron ◽  
Forward Shock ◽  
Electron Positron Pair

The detection of optical rebrightenings and X-ray plateaus in the afterglows of gamma-ray bursts (GRBs) challenges the generic external shock model. Recently, we have developed a numerical method to calculate the dynamics of the system consisting of a forward shock and a reverse shock. Here, we briefly review the applications of this method in the afterglow theory. By relating these diverse features to the central engines of GRBs, we find that the steep optical rebrightenings would be caused by the fall-back accretion of black holes, while the shallow optical rebrightenings are the consequence of the injection of the electron-positron-pair wind from the central magnetar. These studies provide useful ways to probe the characteristics of GRB central engines.

scholarly journals Reverse Shock Emission in Gamma-Ray Bursts Revisited

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
He Gao ◽  
Peter Mészáros
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Shock Model ◽  
Intrinsic Properties ◽  
Reverse Shock

A generic synchrotron external shock model is the widely preferred paradigm used to interpret the broadband afterglow data of gamma-ray bursts (GRBs), including predicted observable signatures from a reverse shock which have been confirmed by observations. Investigations of the nature of the reverse shock emission can provide valuable insights into the intrinsic properties of the GRB ejecta. Here we briefly review the standard and the extended models of the reverse shock emission, discussing the connection between the theory and observations, including the implications of the latest observational advances.

scholarly journals Exceptionally bright optical emission from a rare and distant gamma-ray burst

2021 ◽  
Author(s):  
Gor Oganesyan ◽  
Sergey Karpov ◽  
Martin Jelinek ◽  
Gregory Beskin ◽  
Samuele Ronchini ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Massive Stars ◽  
Optical Emission ◽  
Gamma Ray Bursts ◽  
Additional Component ◽  
Relativistic Jets ◽  
X Ray ◽  
Forward Shock ◽  
Multi Wavelength ◽  
Wavelength Emission

Abstract Long gamma-ray bursts (GRBs) are produced by the dissipation of ultra-relativistic jets launched by newly-born black holes after the collapse of massive stars. Right after the luminous and highly variable gamma-ray emission, the multi-wavelength afterglow is released by the external dissipation of the jet in circumburst medium. We report the discovery of a very bright (10 mag) optical emission 28 s after the explosion of the extremely luminous and energetic GRB 210619B located at redshift 1.937. Early multi-filter observations allowed us to witness the end of the shock wave propagation into the GRB ejecta. We observed the spectral transition from a bright reverse to the forward shock emission, demonstrating that the early and late GRB multi-wavelength emission is originated from a very narrow jet propagating into an unusually rarefied interstellar medium. We also find evidence of an additional component of radiation, coming from the jet wings which is able explain the uncorrelated optical/X-ray emission.

scholarly journals Challenging the Forward Shock Model with the 80 Ms Follow up of the X-ray Afterglow of Gamma-Ray Burst 130427A

Galaxies ◽  
2017 ◽  
Vol 5 (1) ◽  
pp. 6 ◽  
Author(s):  
Massimiliano De Pasquale ◽  
Mathew Page ◽  
David Kann ◽  
Samantha Oates ◽  
Steve Schulze ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Shock Model ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Forward Shock

scholarly journals Similar phenomena at different scales: black holes, the Sun, γ-ray bursts, supernovae, galaxies and galaxy clusters

2006 ◽  
Vol 2 (14) ◽  
pp. 41-62 ◽  
Author(s):  
Shuang Nan Zhang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
The Sun ◽  
Physical Processes ◽  
X Ray ◽  
Physical Mechanisms ◽  
X Ray Binaries ◽  
Fundamental Physical

AbstractMany similar phenomena occur in astrophysical systems with spatial and mass scales different by many orders of magnitudes. For examples, collimated outflows are produced from the Sun, proto-stellar systems, gamma-ray bursts, neutron star and black hole X-ray binaries, and supermassive black holes; various kinds of flares occur from the Sun, stellar coronae, X-ray binaries and active galactic nuclei; shocks and particle acceleration exist in supernova remnants, gamma-ray bursts, clusters of galaxies, etc. In this report I summarize briefly these phenomena and possible physical mechanisms responsible for them. I emphasize the importance of using the Sun as an astrophysical laboratory in studying these physical processes, especially the roles magnetic fields play in them; it is quite likely that magnetic activities dominate the fundamental physical processes in all of these systems.As a case study, I show that X-ray lightcurves from solar flares, black hole binaries and gamma-ray bursts exhibit a common scaling law of non-linear dynamical properties, over a dynamical range of several orders of magnitudes in intensities, implying that many basic X-ray emission nodes or elements are inter-connected over multi-scales. A future high timing and imaging resolution solar X-ray instrument, aimed at isolating and resolving the fundamental elements of solar X-ray lightcurves, may shed new lights onto the fundamental physical mechanisms, which are common in astrophysical systems with vastly different mass and spatial scales. Using the Sun as an astrophysical laboratory, “Applied Solar Astrophysics” will deepen our understanding of many important astrophysical problems.

scholarly journals Late Afterglow Bump/Plateau around the Jet Break: Signature of a Free-to-shocked Wind Environment in Gamma-Ray Burst

2021 ◽  
Vol 922 (1) ◽  
pp. 22
Author(s):  
Xiao-Yan Li ◽  
Da-Bin Lin ◽  
Jia Ren ◽  
Shu-Jin Hou ◽  
Yu-Fei Li ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Jet Flow ◽  
Gamma Ray Bursts ◽  
Constant Density ◽  
Viewing Angle ◽  
Wind Environment ◽  
X Ray ◽  
Forward Shock ◽  
Characteristic Angle ◽  
Steep Decay

Abstract A number of gamma-ray bursts (GRBs) exhibit the simultaneous bumps in their optical and X-ray afterglows around the jet break. These bumps are similar to the afterglows of GRB 170817A, except preceded by a long shallow decay. Its origin is unclear. We suggest that these late simultaneous bumps may sound a transition of circumburst environment from a free-wind medium to a constant density medium, e.g., the shocked-wind medium. In this paper, we study the emission of an external-forward shock propagating in a free-to-shocked wind environment at different viewing angles. The late simultaneous bumps/plateaux followed by a steep decay are found in the optical and X-ray afterglows for high-viewing-angle observers. In addition, these theoretical bumps are preceded by a long plateau or shallow decay, which is formed during the external-forward shock propagating in the free-wind environment. For low-viewing-angle observers, the above bumps also appear but only in the situation where the structured jet has a low characteristic angle and the deceleration radius of the in-core jet flow is at around or beyond the free-wind boundary. We search GRBs for afterglows with the late simultaneous optical and X-ray bumps followed by a steep decay. GRBs 120326A, 100901A, 100814A, and 120404A are obtained. We find that an off-core (in-core) observed external-forward shock in a free-to-shocked wind environment can well explain the optical and X-ray afterglows in GRBs 120326A, 100901A, and 100814A (GRB 120404A).

scholarly journals Evolution of an electron-positron plasma produced by induced gravitational collapse in binary-driven hypernovae

2018 ◽  
Vol 168 ◽  
pp. 04009 ◽  
Author(s):  
J. D. Melon Fuksman ◽  
L. Becerra ◽  
C. L. Bianco ◽  
M. Karlica ◽  
M. Kovacevic ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gravitational Collapse ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Relativistic Hydrodynamics ◽  
X Ray ◽  
The Past ◽  
Electron Positron ◽  
Prompt Emission

The binary-driven hypernova (BdHN) model has been introduced in the past years, to explain a subfamily of gamma-ray bursts (GRBs) with energies Eiso ≥ 1052 erg associated with type Ic supernovae. Such BdHNe have as progenitor a tight binary system composed of a carbon-oxigen (CO) core and a neutron star undergoing an induced gravitational collapse to a black hole, triggered by the CO core explosion as a supernova (SN). This collapse produces an optically-thick e+e- plasma, which expands and impacts onto the SN ejecta. This process is here considered as a candidate for the production of X-ray flares, which are frequently observed following the prompt emission of GRBs. In this work we follow the evolution of the e+e- plasma as it interacts with the SN ejecta, by solving the equations of relativistic hydrodynamics numerically. Our results are compatible with the Lorentz factors estimated for the sources that produce the flares, of typically Γ ≲ 4.

scholarly journals Testing the External-Shock Model of Gamma-Ray Bursts Using the Late-Time Simultaneous Optical and X-Ray Afterglows

2007 ◽  
Vol 668 (2) ◽  
pp. L95-L98 ◽  
Author(s):  
Yuji Urata ◽  
Ryo Yamazaki ◽  
Takanori Sakamoto ◽  
Kuiyun Huang ◽  
Weikang Zheng ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Late Time ◽  
Shock Model ◽  
X Ray

The X-ray luminosity function of short gamma-ray bursts

2021 ◽  
Vol 366 (4) ◽  
Author(s):  
Zhi-Ying Liu ◽  
Fu-Wen Zhang ◽  
Si-Yuan Zhu
Keyword(s):  
Luminosity Function ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
X Ray

scholarly journals Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

2020 ◽  
Vol 499 (4) ◽  
pp. 5986-5992
Author(s):  
Nikhil Sarin ◽  
Paul D Lasky ◽  
Gregory Ashton
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Dipole Radiation ◽  
X Ray ◽  
Radiative Efficiency ◽  
Central Engine ◽  
Radiative Losses ◽  
Wave Emission ◽  
Prompt Emission

ABSTRACT The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as $n=4.85^{+0.11}_{-0.15}$ suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.

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