scholarly journals An early peak in the radio light curve of short-duration gamma-ray burst 200826A

2021 ◽  
Vol 503 (2) ◽  
pp. 2966-2972
Author(s):  
Lauren Rhodes ◽  
Rob Fender ◽  
David R A Williams ◽  
Kunal Mooley
Keyword(s):  
Light Curve ◽  
Short Duration ◽  
Gamma Ray ◽  
Lorentz Factor ◽  
Opening Angle ◽  
Absorption Frequency ◽  
Gamma Ray Burst ◽  
Early Peak ◽  
Forward Shock ◽  
Radio Band

ABSTRACT We present the results of radio observations from the eMERLIN telescope combined with X-ray data from Swift for the short-duration gamma-ray burst (GRB) 200826A, located at a redshift of 0.71. The radio light curve shows evidence of a sharp rise, a peak around 4–5 d post-burst, followed by a relatively steep decline. We provide two possible interpretations based on the time at which the light curve reached its peak. (1) If the light curve peaks earlier, the peak is produced by the synchrotron self-absorption frequency moving through the radio band, resulting from the forward shock propagating into a wind medium and (2) if the light curve peaks later, the turnover in the light curve is caused by a jet break. In the former case we find a minimum equipartition energy of ∼3 × 1047 erg and bulk Lorentz factor of ∼5, while in the latter case we estimate the jet opening angle of ∼9–16°. Due to the lack of data, it is impossible to determine which is the correct interpretation, however due to its relative simplicity and consistency with other multiwavelength observations which hint at the possibility that GRB 200826A is in fact a long GRB, we prefer the scenario one over scenario two.

scholarly journals Afterglow light curves from misaligned structured jets

2020 ◽  
Vol 493 (3) ◽  
pp. 3521-3534 ◽  
Author(s):  
Paz Beniamini ◽  
Jonathan Granot ◽  
Ramandeep Gill
Keyword(s):  
Light Curve ◽  
Gamma Ray ◽  
Lorentz Factor ◽  
Light Curves ◽  
Opening Angle ◽  
Model Parameters ◽  
Narrow Strip ◽  
Double Peaks ◽  
Wide Range ◽  
Jet Structure

ABSTRACT GRB 170817A/GW 170817 is the first gamma-ray burst (GRB) clearly viewed far from the GRB jet’s symmetry axis. Its afterglow was densely monitored over a wide range of frequencies and times. It has been modelled extensively, primarily numerically, and although this endeavour was very fruitful, many of the underlying model parameters remain undetermined. We provide analytic modelling of GRB afterglows observed off-axis, considering jets with a narrow core (of half-opening angle θc) and power-law wings in energy per unit solid angle (ϵ = ϵcΘ−a where Θ = [1 + (θ/θc)2]1/2) and initial specific kinetic energy (Γ0 − 1 = [Γc, 0 − 1]Θ−b), as well as briefly discuss Gaussian jets. Our study reveals qualitatively different types of light curves that can be viewed in future off-axis GRBs, with either single or double peaks, depending on the jet structure and the viewing angle. Considering the light-curve shape rather than the absolute normalizations of times and/or fluxes, removes the dependence of the light curve on many of the highly degenerate burst parameters. This study can be easily used to determine the underlying jet structure, significantly reduce the effective parameter space for numerical fitting attempts and provide physical insights. As an illustration, we show that for GRB 170817A, there is a strong correlation between the allowed values of Γc, 0 and b, leading to a narrow strip of allowed solutions in the Γc, 0–b plane above some minimal values Γc, 0 ≳ 40, b ≳ 1.2. Furthermore, the Lorentz factor of the material dominating the early light curve can be constrained by three independent techniques to be Γ0(θmin, 0) ≈ 5–7.

Afterglows from Jetted Gamma-Ray-Burst Remnant: Does the Light Curve Break?

2000 ◽  
Vol 17 (10) ◽  
pp. 778-780 ◽  
Author(s):  
Huang Yong-Feng ◽  
Dai Zi-Gao ◽  
Lu Tan
Keyword(s):  
Light Curve ◽  
Gamma Ray ◽  
Gamma Ray Burst

scholarly journals Luminous supernovae associated with ultra-long gamma-ray bursts from hydrogen-free progenitors extended by pulsational pair-instability

2020 ◽  
Vol 641 ◽  
pp. L10
Author(s):  
Takashi J. Moriya ◽  
Pablo Marchant ◽  
Sergei I. Blinnikov
Keyword(s):  
Light Curve ◽  
Energy Input ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Decay Energy ◽  
Slow Cooling ◽  
Gamma Ray Burst ◽  
The Core ◽  
Optical Light Curve

We show that the luminous supernovae associated with ultra-long gamma-ray bursts can be related to the slow cooling from the explosions of hydrogen-free progenitors that are extended by pulsational pair-instability. We have recently shown that some rapidly-rotating hydrogen-free gamma-ray burst progenitors that experience pulsational pair-instability can keep an extended structure caused by pulsational pair-instability until the core collapse. These types of progenitors have large radii exceeding 10 R⊙ and they sometimes reach beyond 1000 R⊙ at the time of the core collapse. They are, therefore, promising progenitors of ultra-long gamma-ray bursts. Here, we perform light-curve modeling of the explosions of one extended hydrogen-free progenitor with a radius of 1962 R⊙. The progenitor mass is 50 M⊙ and 5 M⊙ exists in the extended envelope. We use the one-dimensional radiation hydrodynamics code STELLA in which the explosions are initiated artificially by setting given explosion energy and 56Ni mass. Thanks to the large progenitor radius, the ejecta experience slow cooling after the shock breakout and they become rapidly evolving (≲10 days), luminous (≳1043 erg s−1) supernovae in the optical even without energy input from the 56Ni nuclear decay when the explosion energy is more than 1052 erg. The 56Ni decay energy input can affect the light curves after the optical light-curve peak and make the light-curve decay slowly when the 56Ni mass is around 1 M⊙. They also have a fast photospheric velocity above 10 000 km s−1 and a hot photospheric temperature above 10 000 K at around the peak luminosity. We find that the rapid rise and luminous peak found in the optical light curve of SN 2011kl, which is associated with the ultra-long gamma-ray burst GRB 111209A, can be explained as the cooling phase of the extended progenitor. The subsequent slow light-curve decline can be related to the 56Ni decay energy input. The ultra-long gamma-ray burst progenitors we proposed recently can explain both the ultra-long gamma-ray burst duration and the accompanying supernova properties. When the gamma-ray burst jet is off-axis or choked, the luminous supernovae could be observed as fast blue optical transients without accompanying gamma-ray bursts.

scholarly journals Evidence for chromatic X-ray light-curve breaks in Swift gamma-ray burst afterglows and their theoretical implications

2006 ◽  
Vol 369 (4) ◽  
pp. 2059-2064 ◽  
Author(s):  
A. Panaitescu ◽  
P. Mészáros ◽  
D. Burrows ◽  
J. Nousek ◽  
N. Gehrels ◽  
...  
Keyword(s):  
Light Curve ◽  
Gamma Ray ◽  
Gamma Ray Burst ◽  
X Ray

scholarly journals MAGNETOHYDRODYNAMIC EFFECTS IN RELATIVISTIC EJECTA

2010 ◽  
Vol 19 (06) ◽  
pp. 991-996
Author(s):  
YOSUKE MIZUNO ◽  
BING ZHANG ◽  
BRUNO GIACOMAZZO ◽  
KEN-ICHI NISHIKAWA ◽  
PHILIP E. HARDEE ◽  
...  
Keyword(s):  
Rarefaction Wave ◽  
Gamma Ray ◽  
Flux Ratio ◽  
Lorentz Factor ◽  
Magnetic Pressure ◽  
Initial Value ◽  
Reverse Shock ◽  
Thermal Pressure ◽  
Wave Regime ◽  
Forward Shock

We study the problem of deceleration of an arbitrarily magnetized relativistic ejecta in a static unmagnetized medium and its connection to the physics of gamma-ray bursts (GRBs). By computing exact solutions of the Riemann problem describing this scenario, we find that with the same initial Lorentz factor, the reverse shock becomes progressively weaker with increasing magnetization parameter σ (the Poynting-to-kinetic flux ratio). The reverse shock becomes a rarefaction wave when σ exceeds a critical value defined by the balance between magnetic pressure in the ejecta and thermal pressure in the forward shock. In the rarefaction wave regime, the rarefied region is accelerated to a Lorentz factor that is significantly larger than the initial value due to the strong magnetic pressure in the ejecta. We discuss the implications for models of GRBs.

scholarly journals OBSERVATIONAL IMPLICATIONS OF GAMMA-RAY BURST AFTERGLOW JET SIMULATIONS AND NUMERICAL LIGHT CURVE CALCULATIONS

2012 ◽  
Vol 751 (2) ◽  
pp. 155 ◽  
Author(s):  
Hendrik J. van Eerten ◽  
Andrew I. MacFadyen
Keyword(s):  
Light Curve ◽  
Gamma Ray ◽  
Gamma Ray Burst

scholarly journals On the cosmological evolution of long gamma-ray burst properties

2019 ◽  
Vol 488 (4) ◽  
pp. 5823-5832 ◽  
Author(s):  
Nicole M Lloyd-Ronning ◽  
Aycin Aykutalp ◽  
Jarrett L Johnson
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Selection Effect ◽  
Cosmological Evolution ◽  
Opening Angle ◽  
Redshift Distribution ◽  
Isotropic Energy ◽  
Gamma Ray Burst

ABSTRACT We examine the relationship between a number of long gamma-ray burst (lGRB) properties (isotropic emitted energy, luminosity, intrinsic duration, jet opening angle) and redshift. We find that even when accounting for conservative detector flux limits, there appears to be a significant correlation between isotropic equivalent energy and redshift, suggesting cosmological evolution of the lGRB progenitor. Analysing a sub-sample of lGRBs with jet opening angle estimates, we find the beaming-corrected lGRB emitted energy does not correlate with redshift, but jet opening angle does. Additionally, we find a statistically significant anticorrelation between the intrinsic prompt duration and redshift, even when accounting for potential selection effects. We also find that, for a given redshift, isotropic energy is positively correlated with intrinsic prompt duration. None of these GRB properties appear to be correlated with galactic offset. From our selection-effect-corrected redshift distribution, we estimate a co-moving rate density for lGRBs, and compare this to the global cosmic star formation rate (SFR). We find the lGRB rate mildly exceeds the global star formation rate between a redshift of 3 and 5, and declines rapidly at redshifts above this (although we cannot constrain the lGRB rate above a redshift of about 6 due to sample incompleteness). We find the lGRB rate diverges significantly from the SFR at lower redshifts. We discuss both the correlations and lGRB rate density in terms of various lGRB progenitor models and their apparent preference for low-metallicity environments.

scholarly journals CONSTRAINING THE BULK LORENTZ FACTOR OF GAMMA-RAY BURST OUTFLOW IN THE MAGNETIC-DOMINATED JET MODEL

2012 ◽  
Vol 759 (2) ◽  
pp. 129 ◽  
Author(s):  
Zhe Chang ◽  
Hai-Nan Lin ◽  
Yunguo Jiang
Keyword(s):  
Gamma Ray ◽  
Lorentz Factor ◽  
Gamma Ray Burst

scholarly journals Multiwavelength observations of GRB afterglows

2011 ◽  
Vol 7 (S279) ◽  
pp. 58-66
Author(s):  
Alberto J. Castro-Tirado
Keyword(s):  
Gamma Ray ◽  
Early Time ◽  
Global Networks ◽  
Gamma Ray Burst ◽  
French Alps ◽  
Physical Mechanisms ◽  
Forward Shock ◽  
Robotic Telescopes ◽  
Emission Phase ◽  
Multiwavelength Observations

AbstractMultiwavelength observations of gamma-ray burst afterglows are presented, in particular those in the optical and millimetre wavelengths. I will focus on the observations mostly carried out at Spanish ground-based observatories (mainly the 10.4m GTC) and at the Plateau de Bure Interferometer in the French Alps. The importance of global networks of robotic telescopes (like BOOTES, established worldwide) for early time observations in order to put constraints on the physical mechanisms of the GRB early time emission phase is also discussed. The overall observational efforts provide additional clues for a better understanding of the reverse and forward shock. Finally I will report on the Lomonosov/UFFO-p capabilities taking into account its launch in 2012.

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