scholarly journals Evidence of X-Ray Plateaus Driven by the Magnetar Spindown Winds in Gamma-Ray Burst Afterglows

2021 ◽  
Vol 922 (2) ◽  
pp. 102
Author(s):  
Shu-Jin Hou ◽  
Shuang Du ◽  
Tong Liu ◽  
Hui-Jun Mu ◽  
Ren-Xin Xu
Keyword(s):  
Gamma Ray ◽  
Normal Component ◽  
Gamma Ray Bursts ◽  
Cutting Edge ◽  
Decay Phase ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Central Engine

Abstract The central engine of gamma-ray bursts (GRBs) remains an open and cutting-edge topic in the era of multimessenger astrophysics. X-ray plateaus appear in some GRB afterglows, which are widely considered to originate from the spindown of magnetars. According to the stable magnetar scenario of GRBs, an X-ray plateau and a decay phase ∼t −2 should appear in X-ray afterglows. Meanwhile, the “normal” X-ray afterglow is produced by the external shock from a GRB fireball. We analyze the Neil Gehrels Swift GRB data, then find three gold samples that have an X-ray plateau and a decay phase ∼t −2 superimposed on the jet-driven normal component. Based on these features of the lightcurves, we argue that the magnetars should be the central engines of these three GRBs. Future joint multimessenger observations might further test this possibility, which can then be beneficial to constrain GRB physics.

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.

scholarly journals Gamma-Ray Burst Observations with BATSE

1998 ◽  
Vol 188 ◽  
pp. 159-162
Author(s):  
Gerald J. Fishman
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Gamma Ray Burst ◽  
New Era ◽  
X Ray ◽  
Time Profiles ◽  
Random Direction ◽  
Wide Range ◽  
New Phenomena

Gamma-ray bursts (GRBs) will be recorded as one of the outstanding new phenomena discovered in astronomy this century. About once per day, a burst of gamma rays appears from a random direction on the sky. Often, the burst outshines all other sources of gamma-rays in the sky, combined. This paper reviews some of the key observed phenomenon of bursts in the hard x-ray/gamma-ray region, as observed with the BATSE experiment on the Compton Gamma Ray Observatory. The observed time profiles, spectral properties and durations of gamma-ray bursts cover a wide range. Recent breakthroughs in the observation of gamma-ray burst counterparts and afterglows in other wavelength regions have marked the beginning of a new era in gamma-ray burst research. Those observations are described in following papers in these proceedings.

scholarly journals Discovery of X-Ray Counterparts to Gamma Ray Bursts by BeppoSAX

1998 ◽  
Vol 188 ◽  
pp. 163-166
Author(s):  
L. Piro
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Gamma Ray Burst ◽  
X Ray

The nature of Gamma-Ray Burst (GRB) has been the object of many investigations but their origin has remained a mistery primarily for the difficulties in finding a counterpart. This difficulty derived from the intrinsically poor positioning capability of available GRB detectors.

scholarly journals Probing the Structure of Gamma‐Ray Burst Jets with the Steep Decay Phase of their Early X‐Ray Afterglows

2007 ◽  
Vol 663 (2) ◽  
pp. 1118-1124 ◽  
Author(s):  
Kentaro Takami ◽  
Ryo Yamazaki ◽  
Takanori Sakamoto ◽  
Goro Sato
Keyword(s):  
Gamma Ray ◽  
Decay Phase ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Steep Decay

scholarly journals SWIFT HIGHLIGHTS AND FLARES (BACK TO THE DRAWING BOARD?)

2011 ◽  
Vol 20 (10) ◽  
pp. 1733-1743 ◽  
Author(s):  
G. CHINCARINI ◽  
R. MARGUTTI
Keyword(s):  
Early Universe ◽  
Gamma Ray ◽  
Gamma Ray Burst ◽  
New Era ◽  
X Ray ◽  
Celestial Object ◽  
Central Engine ◽  
Drawing Board

Swift opened up a new era in the study of gamma-ray burst sources (GRB). Among a variety of discoveries made possible by Swift, here we focus on GRB 090423, the event at z = 8.2 which currently holds the record of the most distant celestial object ever caught by human instrumentation. This GRB allowed us to have a direct look at the early Universe. The central engine activity giving origin to the GRB emission is also discussed starting from the observational findings of an updated GRB X-ray flares catalog.

scholarly journals Statistical Analyses of the Energies of X-Ray Plateaus and Flares in Gamma-Ray Bursts

2022 ◽  
Vol 924 (2) ◽  
pp. 69
Author(s):  
Shuang-Xi Yi ◽  
Mei Du ◽  
Tong Liu
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Physical Origin ◽  
Radiation Mechanisms ◽  
Gaussian Distributions ◽  
Emission Energy ◽  
X Ray ◽  
Central Engine ◽  
Positive Correlations ◽  
Prompt Emission

Abstract Distinct X-ray plateau and flare phases have been observed in the afterglows of gamma-ray bursts (GRBs), and most of them should be related to central engine activities. In this paper, we collect 174 GRBs with X-ray plateau phases and 106 GRBs with X-ray flares. There are 51 GRBs that overlap in the two selected samples. We analyze the distributions of the proportions of the plateau energy E plateau and the flare energy E flare relative to the isotropic prompt emission energy E γ,iso. The results indicate that they well meet the Gaussian distributions and the medians of the logarithmic ratios are ∼−0.96 and −1.39 in the two cases. Moreover, strong positive correlations between E plateau (or E flare ) and E γ,iso with slopes of ∼0.95 (or ∼0.80) are presented. For the overlapping sample, the slope is ∼0.80. We argue that most of X-ray plateaus and flares might have the same physical origin but appear with different features because of the different circumstances and radiation mechanisms. We also test the applicabilities of two models, i.e., black holes surrounded by fractured hyperaccretion disks and millisecond magnetars, on the origins of X-ray plateaus and flares.

scholarly journals X-ray plateaus in gamma-ray bursts’ light curves from jets viewed slightly off-axis

2020 ◽  
Vol 492 (2) ◽  
pp. 2847-2857 ◽  
Author(s):  
Paz Beniamini ◽  
Raphaël Duque ◽  
Frédéric Daigne ◽  
Robert Mochkovitch
Keyword(s):  
Gamma Ray ◽  
Large Fraction ◽  
Gamma Ray Bursts ◽  
Point Of View ◽  
Light Curves ◽  
Late Time ◽  
X Ray ◽  
Narrow Region ◽  
Central Engine ◽  
Γ Rays

ABSTRACT Using multiple observational arguments, recent work has shown that cosmological gamma-ray bursts (GRBs) are typically viewed at angles within, or close to the cores of their relativistic jets. One of those arguments relied on the lack of tens-of-days-long periods of very shallow evolution that would be seen in the afterglow light curves of GRBs viewed at large angles. Motivated by these results, we consider that GRBs efficiently produce γ-rays only within a narrow region around the core. We show that, on these near-core lines of sight, structured jets naturally produce shallow phases in the X-ray afterglow of GRBs. These plateaus would be seen by a large fraction of observers and would last between 102–105 s. They naturally reproduce the observed distributions of time-scales and luminosities as well as the intercorrelations between plateau duration, plateau luminosity, and prompt γ-ray energy. An advantage of this interpretation is that it involves no late-time energy injection which would be both challenging from the point of view of the central engine and, as we show here, less natural given the observed correlations between plateau and prompt properties.

scholarly journals Magnetar as Central Engine of Gamma-Ray Bursts: Quasi-universal Jet, Event Rate, and X-Ray Luminosity Function of Dipole Radiations

2020 ◽  
Vol 894 (1) ◽  
pp. 52
Author(s):  
Wen-Jin Xie ◽  
Le Zou ◽  
Hong-Bang Liu ◽  
Shan-Qin Wang ◽  
En-Wei Liang
Keyword(s):  
Luminosity Function ◽  
Gamma Ray ◽  
Event Rate ◽  
Gamma Ray Bursts ◽  
X Ray ◽  
Central Engine

scholarly journals Can we quickly flag ultra-long gamma-ray bursts?

2019 ◽  
Vol 486 (2) ◽  
pp. 2471-2476 ◽  
Author(s):  
B Gendre ◽  
Q T Joyce ◽  
N B Orange ◽  
G Stratta ◽  
J L Atteia ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Wide Field ◽  
Exact Nature ◽  
X Ray ◽  
Central Engine ◽  
Long Duration ◽  
Limited Coverage

Abstract Ultra-long gamma-ray bursts are a class of high-energy transients lasting several hours. Their exact nature is still elusive, and several models have been proposed to explain them. Because of the limited coverage of wide-field gamma-ray detectors, the study of their prompt phase with sensitive narrow-field X-ray instruments could help in understanding the origin of ultra-long GRBs. However, the observers face a true problem in rapidly activating follow-up observations, due to the challenging identification of an ultra-long GRB before the end of the prompt phase. We present here a comparison of the prompt properties available after a few tens of minutes of a sample of ultra-long GRBs and normal long GRBs, looking for prior indicators of the long duration. We find that there is no such clear prior indicator of the duration of the burst. We also found that statistically, a burst lasting at least 10 and 20 minutes has respectively $28{{\ \rm per\ cent}}$ and $50{{\ \rm per\ cent}}$ probability to be an ultralong event. These findings point towards a common central engine for normal long and ultra-long GRBs, with the collapsar model privileged.

scholarly journals A Review of Gamma-Ray Burst Observations

1987 ◽  
Vol 125 ◽  
pp. 477-487
Author(s):  
W. Doyle Evans ◽  
John G. Laros
Keyword(s):  
Neutron Stars ◽  
Spectral Properties ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Gamma Ray Burst ◽  
X Ray

Gamma-ray bursts are generally believed to originate in the vicinity of neutron stars, but the phenomenology is still not understood. In this paper we review the known characteristics of gamma bursts and give new observational results on temporal and spectral properties. We suggest that a class of repeating bursters exists that are spectrally harder than x-ray bursters but significantly softer than “classical” gamma bursts. The March 5, 1979, burst may be the prototype of this class of bursters.

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