scholarly journals Nature of the ultrarelativistic prompt emission phase of GRB 190114C

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
R. Moradi ◽  
J. A. Rueda ◽  
R. Ruffini ◽  
Liang Li ◽  
C. L. Bianco ◽  
...  
Keyword(s):  
Prompt Emission ◽  
Emission Phase

scholarly journals THE LUMINOSITY EVOLUTION OVER THE EQUITEMPORAL SURFACES IN THE PROMPT EMISSION OF GAMMA-RAY BURSTS

2011 ◽  
Vol 20 (10) ◽  
pp. 1919-1929 ◽  
Author(s):  
CARLO LUCIANO BIANCO ◽  
FRANCESCO ALESSANDRO MASSUCCI ◽  
REMO RUFFINI
Keyword(s):  
Arrival Time ◽  
Gamma Ray ◽  
Equations Of Motion ◽  
Visible Region ◽  
Apparent Size ◽  
Gamma Ray Bursts ◽  
Theoretical Interpretation ◽  
Spectral Evolution ◽  
Prompt Emission ◽  
Emission Phase

Due to the ultrarelativistic velocity of the expanding "fireshell" (Lorentz gamma factor γ ~ 102-103), photons emitted at the same time from the fireshell surface do not reach the observer at the same arrival time. In interpreting Gamma-Ray Bursts (GRBs) it is crucial to determine the properties of the EQuiTemporal Surfaces (EQTSs): the locus of points which are source of radiation reaching the observer at the same arrival time. In the current literature this analysis is performed only in the latest phases of the afterglow. Here we study the distribution of the GRB bolometric luminosity over the EQTSs, with special attention to the prompt emission phase. We analyze as well the temporal evolution of the EQTS apparent size in the sky. We use the analytic solutions of the equations of motion of the fireshell and the corresponding analytic expressions of the EQTSs which have been presented in recent works and which are valid for both the fully radiative and the adiabatic dynamics. We find the novel result that at the beginning of the prompt emission the most luminous regions of the EQTSs are the ones closest to the line of sight. On the contrary, in the late prompt emission and in the early afterglow phases the most luminous EQTS regions are the ones closest to the boundary of the visible region. This transition in the emitting region may lead to specific observational signatures, i.e. an anomalous spectral evolution, in the rising part or at the peak of the prompt emission. We find as well an expression for the apparent radius of the EQTS in the sky, valid in both the fully radiative and the adiabatic regimes. Such considerations are essential for the theoretical interpretation of the prompt emission phase of GRBs.

scholarly journals Prevalence of Extra Power-Law Spectral Components in Short Gamma-Ray Bursts

2021 ◽  
Vol 922 (2) ◽  
pp. 255
Author(s):  
Qing-Wen Tang ◽  
Kai Wang ◽  
Liang Li ◽  
Ruo-Yu Liu
Keyword(s):  
Power Law ◽  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
Spectral Feature ◽  
Gamma Ray Bursts ◽  
Spectral Energy ◽  
Spectral Components ◽  
Short Grbs ◽  
Prompt Emission ◽  
Emission Phase

Abstract A prompt extra power-law (PL) spectral component that usually dominates the spectral energy distribution below tens of keV or above ∼10 MeV has been discovered in some bright gamma-ray bursts (GRBs). However, its origin is still unclear. In this paper, we present a systematic analysis of 13 Fermi short GRBs, as of 2020 August, with contemporaneous keV–MeV and GeV detections during the prompt emission phase. We find that the extra PL component is a ubiquitous spectral feature for short GRBs, showing up in all 13 analyzed GRBs. The PL indices are mostly harder than −2.0, which may be well reproduced by considering the electromagnetic cascade induced by ultrarelativistic protons or electrons accelerated in the prompt emission phase. The average flux of these extra PL components positively correlates with that of the main spectral components, which implies they may share the same physical origin.

Relativistic Behavior and Equitemporal Surfaces in Ultra-Relativistic Prompt Emission Phase of Gamma-Ray Bursts

2018 ◽  
Vol 62 (12) ◽  
pp. 905-910
Author(s):  
R. Moradi ◽  
R. Ruffini ◽  
C. L. Bianco ◽  
Y.-C. Chen ◽  
M. Karlica ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Prompt Emission ◽  
Emission Phase

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 Optical Afterglows as Probes for the Central Engine and Fireball of Gamma-Ray Bursts

2012 ◽  
Vol 8 (S290) ◽  
pp. 263-264
Author(s):  
Liang Li ◽  
En-Wei Liang ◽  
He Gao ◽  
Bing Zhang
Keyword(s):  
Statistical Analysis ◽  
Gamma Rays ◽  
Density Profile ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Gamma Ray Bursts ◽  
Prompt Gamma ◽  
Medium Density ◽  
Central Engine ◽  
Prompt Emission

AbstractWell-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are compiled from literature. We identify possible emission components based on our empirical fits and present statistical analysis for these components. We find that the flares are related to prompt emission, suggesting that they could have the same origin in different episodes. The shallow decay segment is not correlated with prompt gamma-rays. It likely signals a long-lasting injected wind from GRB central engines. Early after onset peak is closely related with prompt emission. The ambient medium density profile is likely n ∝ r−1. No correlation between the late re-brightening bump and prompt gamma-rays or the onset bump is found. They may be from another jet component.

The Prompt Emission of GRB 990712 with [ITAL]B[/ITAL][CSC][ITAL]eppo[/ITAL][/CSC][ITAL]SAX[/ITAL]: Evidence of a Transient X-Ray Emission Feature

2001 ◽  
Vol 550 (1) ◽  
pp. L47-L51 ◽  
Author(s):  
F. Frontera ◽  
L. Amati ◽  
M. Vietri ◽  
J. J. M. in ’t Zand ◽  
E. Costa ◽  
...  
Keyword(s):  
Emission Feature ◽  
X Ray ◽  
Prompt Emission

scholarly journals GRB 060714: No Clear Dividing Line between Prompt Emission and X‐Ray Flares

2007 ◽  
Vol 665 (1) ◽  
pp. 554-568 ◽  
Author(s):  
H. A. Krimm ◽  
J. Granot ◽  
F. E. Marshall ◽  
M. Perri ◽  
S. D. Barthelmy ◽  
...  
Keyword(s):  
X Ray ◽  
Prompt Emission ◽  
Dividing Line

scholarly journals A Decreasing Column Density during the Prompt Emission from GRB 000528 Observed withBeppoSAX

2004 ◽  
Vol 614 (1) ◽  
pp. 301-308 ◽  
Author(s):  
F. Frontera ◽  
L. Amati ◽  
D. Lazzati ◽  
E. Montanari ◽  
M. Orlandini ◽  
...  
Keyword(s):  
Column Density ◽  
Prompt Emission
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