Synchrotron radiation in γ-ray bursts prompt emission

Zhang, Bing

doi:10.1038/s41550-020-1041-3

Cited by 24 publications

(23 citation statements)

References 49 publications

(62 reference statements)

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“…Our results suggest an efficient coupling between a slowly decaying magnetic field and the emitting particles. Our findings are generally in agreement with moderately fast and slow cooling regimes of the synchrotron radiation, which is able to reproduce the overall GRB spectral features 36 . In the adiabatic cooling scenario, most of the internal energy is not radiated away before the system substantially expands.…”

Section: Discussionsupporting

confidence: 87%

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Spectral index-flux relation for investigating the origins of steep decay in γ-ray bursts

et al. 2021

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Abstractγ-ray bursts (GRBs) are short-lived transients releasing a large amount of energy (1051 − 1053 erg) in the keV-MeV energy range. GRBs are thought to originate from internal dissipation of the energy carried by ultra-relativistic jets launched by the remnant of a massive star’s death or a compact binary coalescence. While thousands of GRBs have been observed over the last thirty years, we still have an incomplete understanding of where and how the radiation is generated in the jet. Here we show a relation between the spectral index and the flux found by investigating the X-ray tails of bright GRB pulses via time-resolved spectral analysis. This relation is incompatible with the long standing scenario which invokes the delayed arrival of photons from high-latitude parts of the jet. While the alternative scenarios cannot be firmly excluded, the adiabatic cooling of the emitting particles is the most plausible explanation for the discovered relation, suggesting a proton-synchrotron origin of the GRB emission.

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Section: Discussionsupporting

confidence: 87%

“…As a final attempt, we use synchrotron spectrum emitted by a population of particles with an initial energy distribution N(γ) ∝ γ −p . Synchrotron is considered the dominant radiative process in prompt emission of GRBs 4,36 . In the fast cooling regime, the particle distribution becomes…”

Section: Methodsmentioning

confidence: 99%

Spectral index-flux relation for investigating the origins of steep decay in γ-ray bursts

et al. 2021

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“…This may be an indication of intrinsically inefficient emitting particles in GRB outflows, such as protons 24 , since the electron cooling timescale τ e − in a compact and highly magnetized ejecta is catastrophically short (τ e − 1 s 25 ). Our findings are generally in agreement with moderately fast and slow cooling regimes of the synchrotron radiation, which is able to reproduce the overall GRB spectral features 26 . However, our results disfavor models with re-acceleration/slow heating of electrons 27,28 , since when electrons are left unenergized we would again observe HLE-dominated X-ray tails.…”

Section: Discussionsupporting

confidence: 87%

“…As a final attempt, we use synchrotron spectrum emitted by a population of particles with an initial energy distribution N (γ) ∝ γ −p . Synchrotron is considered the dominant radiative process in prompt emission of GRBs 12,26 . In the fast cooling regime, the particle distribution becomes…”

mentioning

confidence: 99%

Unveiling the origin of steep decay in γ-ray bursts

Ronchini¹,

Oganesyan²,

Branchesi³

et al. 2020

Preprint

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γ-ray bursts (GRBs) are short-lived transients releasing a large amount of energy (10^51-10^53 erg) in the keV-MeV energy range. GRBs are thought to originate from internal dissipation of the energy carried by ultra-relativistic jets launched by the remnant of a massive star’s death or a compact binary coalescence. While thousands of GRBs have been observed over the last thirty years, we still have an incomplete understanding of where and how the radiation is generated in the jet. A novel investigation of the GRB emission mechanism, via time-resolved spectral analysis of the X-ray tails of bright GRB pulses, enables us to discover a unique relation between the spectral index and the flux. This relation is incompatible with the long standing scenario invoked to interpret X-ray tails, that is, the delayed arrival of pho-tons from high-latitude parts of the jet. We show that our results provide for the first time evidence of adiabatic cooling and efficient energy exchange between the emitting particles in the relativistic outflows of GRBs.

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“…The radiative process responsible for the production of the prompt emission of GRBs has not been identified yet (e,g, see [91,123]). The spectral shape of the prompt emission, typically observed in the 10 keV-10 MeV energy range, is inconsistent (e.g., Fig.…”

Section: The Nature Of the Prompt Emissionmentioning

confidence: 99%

Gamma ray burst studies with THESEUS

et al. 2021

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Gamma-ray Bursts (GRBs) are the most powerful transients in the Universe, over–shining for a few seconds all other γ-ray sky sources. Their emission is produced within narrowly collimated relativistic jets launched after the core–collapse of massive stars or the merger of compact binaries. THESEUS will open a new window for the use of GRBs as cosmological tools by securing a statistically significant sample of high-z GRBs, as well as by providing a large number of GRBs at low–intermediate redshifts extending the current samples to low luminosities. The wide energy band and unprecedented sensitivity of the Soft X-ray Imager (SXI) and X-Gamma rays Imaging Spectrometer (XGIS) instruments provide us a new route to unveil the nature of the prompt emission. For the first time, a full characterisation of the prompt emission spectrum from 0.3 keV to 10 MeV with unprecedented large count statistics will be possible revealing the signatures of synchrotron emission. SXI spectra, extending down to 0.3 keV, will constrain the local metal absorption and, for the brightest events, the progenitors’ ejecta composition. Investigation of the nature of the internal energy dissipation mechanisms will be obtained through the systematic study with XGIS of the sub-second variability unexplored so far over such a wide energy range. THESEUS will follow the spectral evolution of the prompt emission down to the soft X–ray band during the early steep decay and through the plateau phase with the unique ability of extending above 10 keV the spectral study of these early afterglow emission phases.

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Synchrotron radiation in γ-ray bursts prompt emission

Cited by 24 publications

References 49 publications

Spectral index-flux relation for investigating the origins of steep decay in γ-ray bursts

Spectral index-flux relation for investigating the origins of steep decay in γ-ray bursts

Unveiling the origin of steep decay in γ-ray bursts

Gamma ray burst studies with THESEUS

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