Proton–synchrotron as the radiation mechanism of the prompt emission of gamma-ray bursts?

Ghisellini, G.; Ghirlanda, G.; Oganesyan, G.; Ascenzi, S.; Nava, Lara; Celotti, A.; Salafia, O. S.; Ravasio, M. E.; Ronchi, M.

doi:10.1051/0004-6361/201937244

Cited by 60 publications

(64 citation statements)

References 58 publications

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“…If electrons are responsible for the emission, an extremely small magnetic field would be required [37][38][39] , which is unrealistic for this kind of outflows. Protons radiating through synchrotron emission can solve this problem 40 . Due to their larger mass, they radiate less efficiently than electrons, explaining why adiabatic cooling dominates the spectral evolution.…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%

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

et al. 2021

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“…A prototypical example, GRB 180720B at z = 0.65 (Fig. 6 top left panel) observed by Fermi/GBM, revealed [99] a steep electron energy distribution (inferred from the slope of the high energy power law spectrum) and a relatively small comoving frame magnetic field, which challenge the acceleration mechanisms, the common understanding of the jet composition, and the standard electron-synchrotron scenario [50].…”

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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“…Recently Ghisellini et al (2020) pointed out that is quite challenging to find a self-consistent and 'comfortable' parameter space for models invoking electrons as the synchrotron emitters and proposed a model in which the synchrotron emission it is due to protons. In this proton-synchrotron scenario, the observed marginally fast-cooling spectrum can be explained even at low emitting region size (e.g.…”

Section: Open Problemsmentioning

confidence: 99%

“…Because a big fraction of the whole GRB radiation is released in a region much smaller than the transverse size of the jet, so the radiation energy density is much higher than the case in which the entire surface emits(Ghisellini et al 2020). …”

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confidence: 99%

Electromagnetic counterparts of compact binary mergers

et al. 2021

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The first detection of a binary neutron star merger through gravitational waves and photons marked the dawn of multimessenger astronomy with gravitational waves, and it greatly increased our insight in different fields of astrophysics and fundamental physics. However, many open questions on the physical process involved in a compact binary merger still remain and many of these processes concern plasma physics. With the second generation of gravitational wave interferometers approaching their design sensitivity, the new generation under design study and new X-ray detectors under development, the high energy universe will become more and more a unique laboratory for our understanding of plasma in extreme conditions. In this review, we discuss the main electromagnetic signals expected to follow the merger of two compact objects highlighting the main physical processes involved and some of the most important open problems in the field.

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Proton–synchrotron as the radiation mechanism of the prompt emission of gamma-ray bursts?

Cited by 60 publications

References 58 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

Gamma ray burst studies with THESEUS

Electromagnetic counterparts of compact binary mergers

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