Spectral components in the bright, long GRB 061007: properties of the photosphere and the nature of the outflow

Larsson, Josefin; Ryde, F.; McGlynn, S.; Larsson, Stefan; Ohno, M.; Yamaoka, K.

doi:10.1111/j.1365-2966.2011.18582.x

Cited by 19 publications

(17 citation statements)

References 49 publications

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“…Due to the weakness of the observed signal, most of the analysis is done on time integrated signal, as simply not enough photons are observed. However, when analyzing the data of bright GRBs where a time-resolved analysis could be and indeed was done, it was proven that indeed some part (but not all) of the observed prompt spectra can be well fitted with a thermal (Planck) spectrum [240][241][242][243][244]. This was confirmed by several recent observations done with the Fermi satellite [245][246][247][248][249][250][251].…”

Section: Photospheric Emission and Grb Dynamicsmentioning

confidence: 71%

Plasmas in Gamma-Ray Bursts: Particle Acceleration, Magnetic Fields, Radiative Processes and Environments

Pe’er

2019

Galaxies

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Being the most extreme explosions in the universe, gamma-ray bursts (GRBs) provide a unique laboratory to study various plasma physics phenomena. The complex lightcurve and broad-band, non-thermal spectra indicate a very complicated system on the one hand, but on the other hand provide a wealth of information to study it. In this chapter I focus on recent progress in some of the key unsolved physical problems. These include: (1) Particle acceleration and magnetic field generation in shock waves; (2) Possible role of strong magnetic fields in accelerating the plasmas, and accelerating particles via magnetic reconnection process; (3) Various radiative processes that shape the observed lightcurve and spectra, both during the prompt and the afterglow phases, and finally (4) GRB environments and their possible observational signature.

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Section: Photospheric Emission and Grb Dynamicsmentioning

confidence: 71%

Plasmas in Gamma-Ray Bursts: Particle Acceleration, Magnetic Fields, Radiative Processes and Environments

Pe’er

2019

Galaxies

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“…The dashed, red line shows the shape of a Planck spectrum at the temperature that corresponds to the peak of the spectrum. was proposed to explain the deviations from a Planck function that is observed during epoch 1 ; see also Larsson et al 2011).…”

Section: Epochmentioning

confidence: 99%

Observational evidence of dissipative photospheres in gamma-ray bursts

Ryde

Pe’er

Nymark

et al. 2011

Monthly Notices of the Royal Astronomical Society

118

127

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The emission from a gamma-ray burst (GRB) photosphere can give rise to a variety of spectral shapes. The spectrum can retain the shape of a Planck function or it can be broadened and have the shape of a Band function. This fact is best illustrated by studying GRB090902B. The main gamma-ray spectral component is initially close to a Planck function, which can only be explained by emission from the jet photosphere. Later, the same component evolves into a broader Band function. This burst thus provides observational evidence that the photosphere can give rise to a non-thermal spectrum. We show that such a broadening is most naturally explained by subphotospheric dissipation in the jet. The broadening mainly depends on the strength and location of the dissipation, the magnetic field strength and the relation between the energy densities of thermal photons and electrons. We suggest that the evolution in spectral shape observed in GRB090902B is due to a decrease in the bulk Lorentz factor of the flow, leading to the main dissipation becoming subphotospheric. Such a change in the flow parameters can also explain the correlation observed between the peak energy of the spectrum and low-energy power-law slope, α, a correlation commonly observed in GRBs. We conclude that photospheric emission could indeed be a ubiquitous feature during the prompt phase in GRBs and play a decisive role in creating the diverse spectral shapes and spectral evolutions that are observed

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“…Indeed, the spectra of some GRBs are found to be consistent with a photospheric component (e.g., Ryde et al 2010;Larsson et al 2011;Pe'er et al 2012). However, the photosphere model typically predicts α ∼ 1.4 (Deng & Zhang 2014).…”

Section: Introductionmentioning

confidence: 99%

Low-energy Spectra of Gamma-Ray Bursts from Cooling Electrons

Geng

Huang

et al. 2018

ApJS

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The low-energy spectra of gamma-ray bursts' (GRBs) prompt emission are closely related to the energy distribution of electrons, which is further regulated by their cooling processes. We develop a numerical code to calculate the evolution of the electron distribution with given initial parameters, in which three cooling processes (i.e., adiabatic, synchrotron and inverse Compton cooling) and the effect of decaying magnetic field are coherently considered. A sequence of results are presented by exploring the plausible parameter space for both the fireball and the Poynting-flux-dominated regime. Different cooling patterns for the electrons can be identified and they are featured by a specific dominant cooling mechanism. Our results show that the hardening of the low-energy spectra can be attributed to the dominance of synchrotron self-Compton cooling within the internal shock model, or to decaying synchrotron cooling within the Poynting-flux-dominated jet scenario. These two mechanisms can be distinguished by observing the hard low-energy spectra of isolated short pulses in some GRBs. The dominance of adiabatic cooling can also lead to hard low-energy spectra when the ejecta is moving at an extreme relativistic speed. The information from the time-resolved low-energy spectra can help to probe the physical characteristics of the GRB ejecta via our numerical results.

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Spectral components in the bright, long GRB 061007: properties of the photosphere and the nature of the outflow

Cited by 19 publications

References 49 publications

Plasmas in Gamma-Ray Bursts: Particle Acceleration, Magnetic Fields, Radiative Processes and Environments

Plasmas in Gamma-Ray Bursts: Particle Acceleration, Magnetic Fields, Radiative Processes and Environments

Observational evidence of dissipative photospheres in gamma-ray bursts

Low-energy Spectra of Gamma-Ray Bursts from Cooling Electrons

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