Gamma-Ray Bursts Induced by Turbulent Reconnection

Lazarían, A.; Zhang, Bing

doi:10.3847/1538-4357/ab2b38

Cited by 38 publications

(30 citation statements)

References 193 publications

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“…A consensus of the synchrotron modelers is that in order to reproduce the data, the emission region needs to be at least two orders of magnitude farther away from the engine than the standard internal shock site 20,27,28,30,36,37 . Such large radii for synchrotron radiation are expected in the Poynting-flux dissipation models invoking repeated collisions 38 or 3 collision-or deceleration-induced magnetic kink instabilities 39 . The large emission radius of the GRB prompt emission is also consistent with the non-detection of high-energy neutrinos from any GRBs 40,41 and the modeling of the "spectral lags" and spectral evolution patterns in GRB pulses 42,43 .…”

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confidence: 81%

Synchrotron radiation in γ-ray bursts prompt emission

Zhang

2020

Nat Astron

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Growing evidence suggests that synchrotron radiation plays a significant role in shaping the spectra of most γ-ray bursts. The relativistic jets producing them likely carry a significant fraction of energy in the form of a Poynting flux.The electromagnetic spectra of γ-ray bursts (GRBs) are usually characterized by a mathematical function invoking an exponentially-connected two-power-law function first proposed in a paper by the Burst And Transient Source Experiment (BATSE) team led by David Band (1957-2009) 1 . In the special session in memory of Band at the 2009 Fermi Symposium, Josh Grindlay, his PhD advisor from Harvard University, challenged GRB theorists to "find the physical meaning" of the "Band function" in 10 years.In the GRB field there was never a lack of models to interpret data. The challenge is rather to "identify" than to "find" the physical meaning of the Band function. Indeed, two leading models proposed long ago could both roughly account for the the general shape of the spectra but both models have one critical flaw regarding the low-energy photon index of the Band function, denoted as α. The measured values of α peak around ∼ −1 with a broad distribution 2, 3 . The first model invokes synchrotron radiation 4, 5 of the electrons accelerated in the energy dissipation regions (internal shocks or magnetic reconnection sites) to account for the observed γ-rays. However, for a typical GRB environment the electrons are in the so-called "fast-cooling" regime that demands 6, 7 α = −1.5. This is too "soft" to account for the data. The second model invokes quasi-thermal emission from a relativistic fireball 8, 9 .The model typically predicts 10, 11 α ∼ +1.5. This becomes too "hard".

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confidence: 81%

Synchrotron radiation in γ-ray bursts prompt emission

Zhang

2020

Nat Astron

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“…The difference of the model in Lazarian, Zhang, and Xu (2018) from other kink-driven models of GRBs (e.g. Drenkhahn and Spruit (2002); Giannios and Spruit (2006); Giannios (2008); McKinney and Uzdensky (2012)) is that the kink instability also induces turbulence (Galsgaard and Nordlund, 1997;Gerrard and Hood, 2003), which drives magnetic fast reconnection.…”

Section: E Flares and Bursts Of Reconnectionmentioning

confidence: 98%

“…However, the simulations were on the global scale and no detailed turbulent reconnection was observed. Lazarian, Zhang, and Xu (2018) used the advances of relativistic turbulent reconnection to improve the ICMART model. The authors also modified the ICMART model by identifying the kink instability as the most probable mechanism of creating the magnetic configurations prone to reconnection and triggering the turbulent reconnection (see Figure 39).…”

Section: E Flares and Bursts Of Reconnectionmentioning

confidence: 99%

3D turbulent reconnection: Theory, tests, and astrophysical implications

Lazarían¹,

et al. 2020

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Magnetic reconnection, topological change in magnetic fields, is a fundamental process in magnetized plasmas. It is associated with energy release in regions of magnetic field annihilation, but this is only one facet of this process. Astrophysical fluid flows normally have very large Reynolds numbers and are expected to be turbulent, in agreement with observations. In strong turbulence magnetic field lines constantly reconnect everywhere and on all scales, thus making magnetic reconnection an intrinsic part of the turbulent cascade. We note in particular that this is inconsistent with the usual practice of regarding magnetic field lines as persistent dynamical elements. A number of theoretical, numerical, and observational studies starting with the Lazarian & Vishniac 1999 paper proposed that 3D turbulence makes magnetic reconnection fast and that magnetic reconnection and turbulence are intrinsically connected. In particular, we discuss the dramatic violation of the textbook concept of magnetic flux-freezing in the presence of turbulence. We demonstrate that in the presence of turbulence the plasma effects are subdominant to turbulence as far as the magnetic reconnection is concerned. The latter fact justifies an MHD-like treatment of magnetic reconnection on all scales much larger than the relevant plasma scales. We discuss numerical and observational evidence supporting the turbulent reconnection model. In particular, we demonstrate that the tearing reconnection is suppressed in 3D and, unlike the 2D settings, 3D reconnection induces turbulence that makes magnetic reconnection independent of resistivity. We show that turbulent reconnection dramatically affects key astrophysical processes, e.g. star formation, turbulent dynamo, acceleration of cosmic rays. We provide criticism of the concept of "reconnection-mediated turbulence" and explain why turbulent reconnection is very different from enhanced turbulent resistivity and hyper-resistivity, and why the latter have fatal conceptual flaws.

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“…Whether the GRB prompt emission is produced by synchrotron radiation or quasi-thermal emission from the photosphere (e.g., Vereshchagin 2014; Pe'Er & Ryde 2017) has been discussed and debated for a long time. Synchrotron radiation is expected in models like the internal shock model (Rees & Meszaros 1994;Daigne et al 2011) or the abrupt magnetic dissipation models (Zhang & Yan 2011;Deng et al 2015;Lazarian et al 2019). On the other hand, the photosphere models can be grouped into dissipative (Rees & Mészáros 2005;Pe'er et al 2006;Giannios 2008;Beloborodov 2009;Lazzati & Begelman 2009;Ioka 2010;Ryde et al 2011;Toma et al 2011;Aksenov et al 2013) and nondissipative (Pe'er 2008;Beloborodov 2011;Bégué et al 2013;Lundman et al 2013;Ruffini et al 2013Ruffini et al , 2014Deng & Zhang 2014;Meng et al 2018) models.…”

Section: Physical Implicationsmentioning

confidence: 99%

“Double-tracking” Characteristics of the Spectral Evolution of GRB 131231A: Synchrotron Origin?

Geng

Meng

et al. 2019

ApJ

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The characteristics of the spectral evolution of the prompt emission of gamma-ray bursts (GRBs), which are closely related to the radiation mechanism (synchrotron or photosphere), are still an unsolved subject. Here, by performing the detailed timeresolved spectral fitting of GRB 131231A, which has a very bright and well-defined single pulse, some interesting spectral evolution features have been found. (i) Both the low-energy spectral index α and the peak energy E p exhibit the "flux-tracking" pattern ("double-tracking" characteristics). (ii) The parameter relations, i.e., F (the energy flux)-α, F -E p , and E p -α, along with the analogous Yonetoku E p -L γ,iso relation for the different time-resolved spectra, show strong monotonous (positive) correlations, both in the rising and the decaying phases. (iii) The values of α do not exceed the synchrotron limit (α= -2/3) in all slices across the pulse, favoring the synchrotron origin. We argue that the one-zone synchrotron emission model with the emitter streaming away at a large distance from the central engine can explain all of these special spectral evolution characteristics.

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Gamma-Ray Bursts Induced by Turbulent Reconnection

Cited by 38 publications

References 193 publications

Synchrotron radiation in γ-ray bursts prompt emission

Synchrotron radiation in γ-ray bursts prompt emission

3D turbulent reconnection: Theory, tests, and astrophysical implications

“Double-tracking” Characteristics of the Spectral Evolution of GRB 131231A: Synchrotron Origin?

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