Neutron conversion–diffusion: a new model for structured short gamma-ray burst jets compatible with GRB 170817

Preau, Edwan; Ioka, Kunihito; Mészáros, P.

doi:10.1093/mnras/stab652

Cited by 10 publications

(6 citation statements)

References 66 publications

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“…3.4.3.1 Mixing in the cocoon and the parameter fmix: As previously pointed out, the shocked jet part is very baryonpoor, and its mass density is negligible compared to that of the shocked ejecta part (see Figures 1 and 5) (Bromberg et al 2011). However, as the shocked jet part is adjacent to the dense shocked ejecta part, a fraction of the shocked jet part is exposed to being mixed with the shocked ejecta part (Nakar & Piran 2017; also see Preau et al 2021). Such mixing continues to happen throughout the jet propagation, and the shocked jet part of the cocoon is constantly being created (by and near the jet) and dissipated (in the shocked ejecta part, after being mixed with it); the balance of these two processes determines its final properties (at t b ).…”

Section: Breakout Of the Shocked Jet Cocoonmentioning

confidence: 65%

“…As reviewed in Section 2.3, the cocoon is composed of two distinct parts: the "shocked jet" part (low density and high fraction of internal energy in its total energy) and the "shocked ejecta" part (much higher density and lower internal energy fraction in its total energy) [see Bromberg et al (2011), the inner and outer cocoons in their Figure 1; also see Figure 1]. These two part are adjacent to each other, and are constantly being mixed making them difficult to differentiate (see Nakar & Piran 2017; also see Gottlieb et al 2021 for more details about mixing; see also Preau et al 2021). Hereafter, the "shocked jet" part is used to refer only to fluid elements of the initially pure shocked jet part that are still able to escaped the ejecta (i.e., with β inf > βm) 8 .…”

Section: Breakout Of the Two Components Of The Cocoon: Shocked Ejecta...mentioning

confidence: 99%

“…Such mixing continues to happen throughout the jet propagation, and the shocked jet part of the cocoon is constantly being created (by and near the jet) and dissipated (in the shocked ejecta part, after being mixed with it); the balance of these two processes determines its final properties (at t b ). Therefore, the size of the shocked jet part of the cocoon, at the breakout time, is closely related to the degree of mixing between the two parts of the cocoon (Bromberg et al 2011;Mizuta & Ioka 2013;Nakar & Piran 2017;Harrison et al 2018;Gottlieb et al 2021;Preau et al 2021;etc.). However, the physics of such mixing is not well understood, even with numerical simulation, as it is dependent on resolution, magnetic field, dimensionality, etc.…”

Section: Breakout Of the Shocked Jet Cocoonmentioning

confidence: 99%

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Cocoon breakout and escape from the ejecta of neutron star mergers

Hamidani¹,

Ioka²

2022

Preprint

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The cocoon is an inevitable product of a jet propagating through ambient matter, and takes a fair fraction of the jet energy. In short gamma-ray bursts, the ambient matter is the ejecta from the merger of neutron stars, expanding with a high velocity ∼ 0.2c, in contrast to the static stellar envelope in collapsars. Using 2D relativistic hydrodynamic simulations with the ejecta density profile as ρ ∝ r −2 , we find that the expansion makes a big difference; only 0.5-5% of the cocoon mass escapes from (faster than) the ejecta, with an opening angle 20 • -30 • , while it is ∼ 100% and spherical in collapsars. We also analytically obtain the shares of mass and energies for the escaped and trapped cocoons. Because the mass of the escaped cocoon is small and the trapped cocoon is concealed by the ejecta and the escaped cocoon, we conclude that it is unlikely that the cocoon emission was observed as a counterpart to the gravitational wave event GW170817.

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Section: Breakout Of the Shocked Jet Cocoonmentioning

confidence: 65%

Section: Breakout Of the Two Components Of The Cocoon: Shocked Ejecta...mentioning

confidence: 99%

Section: Breakout Of the Shocked Jet Cocoonmentioning

confidence: 99%

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Cocoon breakout and escape from the ejecta of neutron star mergers

Hamidani¹,

Ioka²

2022

Preprint

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“…The exact relation depends on how the medium is expanding, the ratio of the energy density for the jet to ejecta, and weakly on the timescale. Additionally, particle effects such as neutron conversion-diffusion may contribute to the resultant jet structure (Preau et al 2021).…”

Section: Discussionmentioning

confidence: 99%

Inhomogeneous Jets from Neutron Star Mergers: One Jet to Rule them all

Lamb¹,

Nativi²,

Rosswog³

et al. 2022

Preprint

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The broad, ∼ 4 order of magnitude range in energy, inferred via afterglow observations, for the short Gamma-Ray Burst (GRB) population is difficult to reconcile with the narrow energy distribution expected from neutron star merger progenitors. Using the resultant profiles from 3D hydrodynamic simulations of relativistic jets interacting with neutron star merger wind ejecta, we show how the inhomogeneity of energy and velocity can alter the observed afterglow lightcurve. From a single jet we find that the peak afterglow flux depends sensitively on the observer's line-of-sight: at an inclination within the GRB emitting region we find peak flux variability on the order < 0.5 dex through rotational orientation, and < 1.3 dex for polar inclination. The inferred jet kinetic energy for a fixed parameter afterglow covers ∼ 1/3 of the observed short GRB population. We find a physically motivated, analytic jet structure function via our simulations and include an approximation for the varying collimation due to the merger ejecta mass. We show that by considering the observed range of merger ejecta masses, a short GRB jet population with a single intrinsic energy is capable of explaining the observed broad diversity in short GRB kinetic energies.

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“…If these instabilities grow to large amplitudes, they can lead to substantial entrainment of baryons into the jet which can alter the jet dynamics and its emission properties (Aloy et al 2000;MacFadyen et al 2001;Gottlieb et al 2019;Matsumoto & Masada 2019). Strong mixing of jet material with the cocoon prior to breakout leads to heavy baryon loading especially after the collimation point (see e.g., Preau et al 2021). The degree of mixing is strongly influenced by the jet power, injection angle and density of the stellar medium (e.g., Gottlieb et al 2020): high-power jets with small injection angle propagating in low density medium develop faster moving jet-head and show a smaller degree of mixing.…”

Section: Introductionmentioning

confidence: 99%

High-energy neutrino emission from magnetised jets of rapidly rotating protomagnetars

Bhattacharya¹,

Carpio²,

Murase³

et al. 2022

Preprint

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Relativistic jets originating from protomagnetar central engines can lead to long duration gamma-ray bursts (GRBs) and are considered potential sources of ultrahighenergy cosmic rays and secondary neutrinos. We explore the propagation of such jets through a broad range of progenitors, from stars which have shed their envelopes to supergiants which have not. We use a semi-analytical spindown model for the strongly magnetised and rapidly rotating PNS to investigate the role of central engine properties such as the surface dipole field strength, initial rotation period, and jet opening angle on the interactions and dynamical evolution of the jet-cocoon system. With this model, we determine the properties of the relativistic jet, the mildly-relativistic cocoon, and the collimation shock in terms of system parameters such as the timedependent jet luminosity, injection angle and density profile of the stellar medium. We also analyse the criteria for a successful jet breakout, the maximum energy that can be deposited into the cocoon by the relativistic jet, and structural stability of the magnetised outflow relative to local instabilities. Lastly, we compute the highenergy neutrino emission as these magnetised outflows burrow through their progenitors. Precursor neutrinos from successful GRB jets are unlikely to be detected by IceCube, which is consistent with the results of previous works. On the other hand, we find high-energy neutrinos may be produced for extended progenitors like blue and red supergiants, and we estimate the detectability of neutrinos with next-generation detectors such as IceCube-Gen2.

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Neutron conversion–diffusion: a new model for structured short gamma-ray burst jets compatible with GRB 170817

Cited by 10 publications

References 66 publications

Cocoon breakout and escape from the ejecta of neutron star mergers

Cocoon breakout and escape from the ejecta of neutron star mergers

Inhomogeneous Jets from Neutron Star Mergers: One Jet to Rule them all

High-energy neutrino emission from magnetised jets of rapidly rotating protomagnetars

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