Jet structure in the afterglow phase for gamma-ray bursts with a precessing jet

Huang, Baoquan; Lin, Da-Bin; Liu, Tong; Ren, Jia; Wang, Xiang-Gao; Liu, Hongbang; Liang, En‐Wei

doi:10.1093/mnras/stz1426

Cited by 18 publications

(11 citation statements)

References 80 publications

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“…The reasons are shown as follows. Firstly, the late simultaneous bumps found in these bursts are very similar to those in GRB 170817A, which is formed in an off-axis observed external-forward shock propagating in an interstellar medium (Troja et al 2018;Lamb et al 2019;Troja et al 2019;Huang et al 2019;Ren et al 2020). This implies that the late bumps in GRBs 100814A, 120326A, and 120404A may be formed in an off-axis observed external-forward shock in a homogeneous medium.…”

Section: Discussionmentioning

confidence: 62%

“…Secondly, the external-forward shock with other kinds of structured jet are also studied. For example, Huang et al (2019) has studied the jet structure owing to the jet precession and the corresponding afterglows in a homogeneous environment. Very complex structured jets have been found.…”

Section: Discussionmentioning

confidence: 99%

“…Granot et al (2018) studies the afterglows from 2D relativistic hydrodynamic simulations of a GRB jet propagating in a homogeneous medium. It seems to be the case that the late simultaneous bumps generally appear without preceding by a plateau/shallow decay in the afterglows for a structured jet propagating in a homogeneous medium (e.g., the figures 3 and 5 of Huang et al 2019, the figures 6 and 7 of Granot et al 2018). However, our work could not rule out the scenario that other kinds of structured jet propagating only in a homogeneous medium could explain the observed late simultaneous bumps directly followed by a steep decay and preceded by a plateau/shallow decay in these burst.…”

Section: Discussionmentioning

confidence: 99%

“…The models involved to explain the late simultaneous bumps/plateaux should also explain the steep decay following the bumps/plateaux. Actually, this feature (i.e., the simultaneous bumps/plateaux directly followed by a steep decay) is strongly reminiscent of the afterglows in GRB 170817A, which is formed in an off-axis observed external-forward shock propagating in an interstellar medium (ISM, Troja et al 2018;Lamb et al 2019;Troja et al 2019;Huang et al 2019;Ren et al 2020), of which the mass density is constant. The observations of GRB 170817A reveal an almost achromatic bump followed by a steep decay, which is very similar to the GRBs with late bumps mentioned above.…”

Section: Introductionmentioning

confidence: 96%

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Late Afterglow Bump/Plateau around the Jet Break: Signature of a free-to-shocked wind Environment in Gamma-ray Burst

Li,

Lin,

Ren

et al. 2021

Preprint

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A number of gamma-ray bursts (GRBs) exhibit the late simultaneous bumps in their optical and Xray afterglows around the jet break. Its origin is unclear. Based on the following two facts, we suggest that this feature may sound a transition of circum-burst environment from a free-wind medium to a homogeneous medium. (I) The late bump followed by a steep decay is strongly reminiscent of the afterglows of GRB 170817A, which is attributed to an off-axis observed external-forward shock (eFS) propagating in an interstellar medium. (II) Observations seem to feature a long shallow decay before the late optical bump, which is different from the afterglow of GRB 170817A. In this paper, we study the emission of an eFS propagating in a free-to-shocked wind for on/off-axis observers, where the mass density in the shocked-wind is almost constant. The late simultaneous bumps/plateaux in the optical and X-ray afterglows are really found around the jet break for high-viewing-angle observers. Moreover, there is a long plateau or shallow decay before the late bump in the theoretical light-curves, which is formed during the eFS propagating in the free-wind. For low-viewing-angle observers, the above bumps appear only in the situation that the structured jet has a low characteristic angle and the deceleration radius of the on-axis jet flow is at around or beyond the free-wind boundary. As examples, the X-ray and optical afterglows of GRBs 120326A, 120404A, and 100814A are fitted. We find that an off-axis observed eFS in a free-to-shocked wind can well explain the afterglows in these bursts.

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Section: Discussionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Late Afterglow Bump/Plateau around the Jet Break: Signature of a free-to-shocked wind Environment in Gamma-ray Burst

Li,

Lin,

Ren

et al. 2021

Preprint

Self Cite

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“…After decades of researches, the radiation mechanism of GRB prompt emission is still unclear (e.g., Zhang & Yan 2011;Geng et al 2018Geng et al , 2019Lin et al 2018;Zhang et al 2018aZhang et al ,b, 2021Duan, & Wang 2019a,b;Huang et al 2019;Li et al 2019b;Yang et al 2020;Zhang 2020). The photospheric emission model seems to be a promising scenario (e.g., Abramowicz et al 1991;Thompson 1994;Mészáros & Rees 2000;Rees & Mészáros 2005;Pe'er & Ryde 2011;Fan et al 2012;Lazzati et al 2013;Ruffini et al 2013;Gao & Zhang 2015;Bégué & Pe'er 2015;Pe'er et al 2015;Ryde et al 2017;Acuner & Ryde 2018;Hou et al 2018;Meng et al 2018Meng et al , 2019Li 2019a,c,d;Acuner et al 2020;Wang et al 2020).…”

Section: Introductionmentioning

confidence: 99%

The Photosphere Emission Spectrum of Hybrid Relativistic Outflow for Gamma-ray Bursts

Meng,

Geng,

2021

Preprint

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The photospheric emission in the prompt phase is the natural prediction of the original fireball model for gamma-ray burst (GRB) due to the large optical depth (τ > 1) at the base of the outflow, which is supported by the quasi-thermal components detected in several Fermi GRBs. However, which radiation mechanism (photosphere or synchrotron) dominates in most GRB spectra is still under hot debate. The shape of the observed photosphere spectrum from a pure hot fireball or a pure Poynting-fluxdominated outflow has been investigated before. In this work, we further study the photosphere spectrum from a hybrid outflow containing both a thermal component and a magnetic component with moderate magnetization (σ 0 = L P /L Th ∼ 1 − 10), by invoking the probability photosphere model. The high-energy spectrum from such a hybrid outflow is a power law rather than an exponential cutoff, which is compatible with the observed Band function in large amounts of GRBs. Also, the distribution of the low-energy indices (corresponding to the peak-flux spectra) is found to be quite consistent with the statistical result for the peak-flux spectra of GRBs best-fitted by the Band function, with similar angular profiles of structured jet in our previous works. Finally, the observed distribution of the high-energy indices can be well understood after considering the different magnetic acceleration (due to magnetic reconnection and kink instability) and the angular profiles of dimensionless entropy with the narrower core.

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Varying linear polarisation in the dust-free gamma-ray burst 210610B

Agüí Fernández,

de Ugarte Postigo,

Thöne

et al. 2024

A&A

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Long gamma-ray bursts (GRBs) are produced by the collapse of some very massive stars, that emit ultra-relativistic jets. When the jets collide with the interstellar medium they decelerate and generate the so-called afterglow emission, which has been observed to be polarised. We study the polarimetric evolution of the GRB\,210610B afterglow, at $z=1.1341$. This allows us to evaluate the role of geometric and/or magnetic mechanisms in the GRB afterglow polarisation. We observed GRB\,210610B using imaging polarimetry with CAFOS on the 2.2 m Calar Alto Telescope and FORS2 on the $4 m Very Large Telescope. Complementary optical spectroscopy was obtained with OSIRIS on the 10.4 m Gran Telescopio Canarias. We studied the GRB light-curve from X-rays to the optical bands and the Spectral Energy Distribution (SED). This allowed us to strongly constrain the line-of-sight extinction. Finally, we studied the GRB host galaxy using optical to NIR data to fit the SED and derive its integrated properties. GRB\,210610B had a bright afterglow with a negligible line-of-sight extinction. Polarimetry was obtained at three epochs: during an early plateau phase, at the time when the light curve breaks, and after the light curve steepened. We observe an initial polarisation of $ that goes to zero at the time of the break, and it then again increases to $ with a change in the position angle of $54 deg. The spectrum shows features with very low equivalent widths. This indicate a small amount of material in the line of sight within the host. The lack of dust and the low amount of material in the line of sight to GRB\,210610B allowed us to study the intrinsic polarisation of the GRB optical afterglow. The GRB polarisation signals are consistent with ordered magnetic fields in refreshed shock or/and hydrodynamics-scale turbulent fields in the forward shock.

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Jet structure in the afterglow phase for gamma-ray bursts with a precessing jet

Cited by 18 publications

References 80 publications

Late Afterglow Bump/Plateau around the Jet Break: Signature of a free-to-shocked wind Environment in Gamma-ray Burst

Late Afterglow Bump/Plateau around the Jet Break: Signature of a free-to-shocked wind Environment in Gamma-ray Burst

The Photosphere Emission Spectrum of Hybrid Relativistic Outflow for Gamma-ray Bursts

Varying linear polarisation in the dust-free gamma-ray burst 210610B

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