Dynamics and Emission of Wind-powered Afterglows of Gamma-Ray Bursts: Flares, Plateaus, and Steep Decays

Barkov, Maxim V.; Luo, Yonggang; Lyutikov, Maxim

doi:10.3847/1538-4357/abd5c2

Cited by 9 publications

(6 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We first give an analysis of the wind-FRB models (Metzger et al 2019;Beloborodov 2020) from the point of basic theory of pulsar winds and relativistic shock propagating through the winds, §2. These are the types of "double relativistic explosion" previously considered in various set-up by Lyutikov (2002aLyutikov ( , 2011aLyutikov ( , 2017; Lyutikov & Camilo Jaramillo (2017); Barkov et al (2021). In the main §3 we argue that an effective "magnetic loading" quickly reduces the power of the magnetar's explosion, producing either an EM pulse through the wind, or a confined magnetic structure in pressure balance with the wind.…”

Section: Introductionmentioning

confidence: 77%

“…We assume that some kind of the central engine (a magnetar) produces energetic events on top of the steady wind. This will constitute a type of double relativistic explosion (Lyutikov 2002a(Lyutikov , 2011a(Lyutikov , 2017Lyutikov & Camilo Jaramillo 2017;Barkov et al 2021). First, we solve a formal MHD problem, and then discuss its limitations.…”

Section: Explosions In Relativistic Windsmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic loading of magnetars' flares

Lyutikov

2021

Preprint

Self Cite

View full text Add to dashboard Cite

Magnetars, the likely sources of Fast Radio Bursts (FRBs), produce both steady highly relativistic magnetized winds, and occasional ejection events. We demonstrate that the requirement of conservation of the magnetic flux dominates the overall dynamics of magnetic explosions. This is missed in conventional hydrodynamic models of the ejections as expanding shell with parametrically added magnetic field, as well as one-dimensional models of magnetic disturbances. Most of the initial free energy of an explosion is actually spent on stretching its own internal magnetic field, while doing minimal pdV work against the surrounding. Magnetic explosions from magnetars come into force balance with the pre-flare wind close to the light cylinder. They are then advected quietly with the wind, or propagate as electromagnetic disturbances. No powerful shock waves are generated in the wind.

show abstract

Section: Introductionmentioning

confidence: 77%

Section: Explosions In Relativistic Windsmentioning

confidence: 99%

Magnetic loading of magnetars' flares

Lyutikov

2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…A different type of model was proposed by Lyutikov et al (2017) 65 and Barkov et al (2021) 66 , in which the plateau phase, flares and possible steep slopes immediately after the plateau phase, are all explained by a dominant reverse shock. This reverse shock is different than the "classical" reverse shock 20 predicted as part of the "fireball" model 62,63 because it is assumed to propagate through ultrarelativistic, highly magnetized pulsar-like winds produced by long-lasting central engines.…”

Section: Comparison With Ideas Of Explaining X-ray Plateaumentioning

confidence: 96%

“…Other notable ideas include two components [55][56][57][58] or multi component 59 jet models; forward shock emission in homogeneous media 59 ; scattering by dust/modification of ambient density by gamma-ray trigger 60,61 ; dominant reverse shock emission [62][63][64][65][66] ; evolving micro-physical parameters 46,60 ; and viewing angle effects in which the jets viewed from the off-axis 59,[67][68][69][70][71] . While each of these ideas is capable of explaining the observed plateau under certain conditions, they all require an external addition to the basic "fireball" model scenario, and in some cases they cannot address the full set of properties of the plateau phase (such as the flux, slope or duration).…”

mentioning

confidence: 99%

The X-ray plateau phase of gamma-ray burst originating from an expanding shell with a Lorentz factor of a few tens

Dereli-Bégué

Pe’er

Ryde

et al. 2021

Preprint

View full text Add to dashboard Cite

Gamma-ray bursts (GRBs) are one of the most energetic explosions known in the Universe and are also known to have the most relativistic jets, with initial expansion Lorentz factors of $100< \Gamma_i <1000$ \cite{KP91, Fenimore+93, WL95, LS01, ZLB11, Zou+11, Racusin+11}. Many of these objects have a plateau in their early X-ray light curves (up to thousands of seconds) \cite{Nousek+06, OBrien+06, Zhang+06, Liang+07, Srinivasaragavan+20}. In this phase, the X-ray flux decreases much slower than theoretically expected \cite{MR93} which has puzzled the community for many years. Here, we show that the observed signal during this phase in both the X-ray and the optical bands is naturally obtained within the classical GRB “fireball” model, provided that (i) the initial Lorentz factor of the relativistically expanding jet is of the order of a few tens, rather than a few hundreds, as is often cited in the literature, and (ii) the expansion occurs into a medium-low density “wind” with density typically 3-4 orders of magnitude below the expectation from a Wolf-Rayet star \cite{CL99}. Within this framework, the end of the “plateau” phase (the beginning of the regular afterglow) marks the transition from the coasting phase to the self-similar expansion phase, which follows the scaling laws first derived by Blandford \& McKee.\cite{BM76}. This result therefore implies that the long GRB progenitors are either (i) not Wolf-Rayet stars, or (ii) the properties of the wind ejected by these stars prior to their final explosion are very different than the properties of the wind ejected at earlier times. This result shows that the range of Lorentz factors in GRB jets is much wider than previously thought, and bridges an observational ‘gap’ between mildly relativistic jets\cite{Ghisellini1993} inferred in active galactic nuclei, $\Gamma_i\lesssim 20$, to the much higher Lorentz factors, $\Gamma_i\lesssim 1000$ inferred in a few extreme GRBs\cite{Racusin+11}.

show abstract

“…As such the reverse shock is much less clearly defined than is the forward shock. Including a reverse shock would mean the addition of new parameters beyond those listed in the previous paragraphs (Zhang & Kobayashi 2005;Japelj et al 2014;Barkov et al 2021). Both the angular structure of the blast wave and any reverse shock are complications which we defer to future work.…”

mentioning

confidence: 98%

A semi-analytic afterglow with thermal electrons and synchrotron self-Compton emission

Warren,

Dainotti,

Barkov

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

We extend previous work on gamma-ray burst (GRB) afterglows involving hot thermal electrons at the base of a shock-accelerated tail. Using a physically-motivated electron distribution based on first-principles simulations, we compute broadband emission from radio to TeV gamma-rays. For the first time, we present the effects of a thermal distribution of electrons on synchrotron self-Compton (SSC) emission. The presence of thermal electrons causes temporal and spectral structure across the entire observable afterglow, which is substantively different from models that assume a pure power-law distribution for the electrons. We show that early-time TeV emission is enhanced by more than an order of magnitude for our fiducial parameters, with a time-varying spectral index that does not occur for a pure power law of electrons. We further show that the X-ray "closure relations" take a very different, also time-dependent, form when thermal electrons are present; the shape traced out by the X-ray afterglows is a qualitative match to observations of the traditional decay phase. INTRODUCTIONThe afterglows of gamma-ray bursts (GRBs) were initially used to localize the hosts, determine redshifts, and conclusively demonstrate the cosmological origin of these events (Costa et al. 1997; van Paradijs et al. 1997; Metzger et al. 1997;Bloom et al. 1998). Even before the first afterglows were observed, however, it was known that broadband observations would allow for the determination of the properties of GRBs and their progenitor systems (e.g., Paczyński & Rhoads 1993). A standard picture of GRB afterglows was developed, which assumed a relativistic shock accelerating electrons into a power-law distribution (Sari et al. 1998; Granot & Sari 2002, and countless others); these electrons then produced, by synchrotron radiation, the photons detected at Earth. Despite the simplicity of the model, it has been fitted with great success to numerous afterglows (

show abstract

Dynamics and Emission of Wind-powered Afterglows of Gamma-Ray Bursts: Flares, Plateaus, and Steep Decays

Cited by 9 publications

References 70 publications

Magnetic loading of magnetars' flares

Magnetic loading of magnetars' flares

The X-ray plateau phase of gamma-ray burst originating from an expanding shell with a Lorentz factor of a few tens

A semi-analytic afterglow with thermal electrons and synchrotron self-Compton emission

Contact Info

Product

Resources

About