Polarized Emission from Gamma-Ray Burst Jets

Kobayashi, S.

doi:10.3390/galaxies5040080

Cited by 3 publications

(2 citation statements)

References 35 publications

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“…Most (but not all, e.g., [268]) of the early optical polarimetric observations relevant for the optical flash were done by the RINGO polarimeters on the Liverpool telescope [269][270][271][272][273][274][275][276][277]. Combining photometric and polarimetric observations [278], they concluded that their data clearly indicates that all epochs in which significant (linear) polarization was measured were dominated by emission from the reverse shock (while the optical afterglow emission from the forward external shock was sub-dominant). Here are a few examples.…”

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confidence: 99%

GRB Polarization: A Unique Probe of GRB Physics

2021

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Over half a century from the discovery of gamma-ray bursts (GRBs), the dominant radiation mechanism responsible for their bright and highly variable prompt emission remains poorly understood. Spectral information alone has proven insufficient for understanding the composition and main energy dissipation mechanism in GRB jets. High-sensitivity polarimetric observations from upcoming instruments in this decade may help answer such key questions in GRB physics. This article reviews the current status of prompt GRB polarization measurements and provides comprehensive predictions from theoretical models. A concise overview of the fundamental questions in prompt GRB physics is provided. Important developments in gamma-ray polarimetry including a critical overview of different past instruments are presented. Theoretical predictions for different radiation mechanisms and jet structures are confronted with time-integrated and time-resolved measurements. The current status and capabilities of upcoming instruments regarding the prompt emission are presented. The very complimentary information that can be obtained from polarimetry of X-ray flares as well as reverse-shock and early to late forward-shock (afterglow) emissions are highlighted. Finally, promising directions for overcoming the inherent difficulties in obtaining statistically significant prompt-GRB polarization measurements are discussed, along with prospects for improvements in the theoretical modeling, which may lead to significant advances in the field.

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confidence: 99%

GRB Polarization: A Unique Probe of GRB Physics

2021

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“…[258]) of the early optical polarimetric observations relevant for the optical flash were done by the RINGO polarimeters on the Liverpool telescope [243,[259][260][261][262][263][264][265][266]. Combining photometric and polarimetric observations [267] they conclude that their data clearly indicates that all epochs in which significant (linear) polarization was measured were dominated by emission from the reverse shock (while the optical afterglow emission from the forward external shock was sub-dominant). Here are a few examples.…”

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confidence: 99%

GRB Polarization: A Unique Probe of GRB Physics

Gill¹,

Kole²,

Granot³

2021

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Radio Linear Polarization of GRB Afterglows: Instrumental Systematics in ALMA Observations of GRB 171205A

Laskar

Hull

Cortés

2020

ApJ

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Polarization measurements of gamma-ray burst (GRB) afterglows are a promising means of probing the structure, geometry, and magnetic composition of relativistic GRB jets. However, a precise treatment of instrumental calibration is vital for a robust physical interpretation of polarization data, requiring tests of and validations against potential instrumental systematics. We illustrate this with Atacama Large Millimeter/Sub-millimeter Array (ALMA) Band 3 (97.5 GHz) observations of GRB 171205A taken ≈5.19 days after the burst, where a detection of linear polarization was recently claimed. We describe a series of tests for evaluating the stability of polarization measurements with ALMA. Using these tests to reanalyze and evaluate the archival ALMA data, we uncover systematics in the polarization calibration at the ≈0.09% level. We derive a 3σ upper limit on the linearly polarized intensity of P < 97.2 μJy, corresponding to an upper limit on the linear fractional polarization of ΠL < 0.30%, in contrast to the previously claimed detection. Our upper limit improves upon existing constraints on the intrinsic polarization of GRB radio afterglows by a factor of 3. We discuss this measurement in the context of constraints on the jet magnetic field geometry. We present a compilation of polarization observations of GRB radio afterglows, and demonstrate that a significant improvement in sensitivity is desirable for eventually detecting signals polarized at the ≈0.1% level from typical radio afterglows.

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Polarized Emission from Gamma-Ray Burst Jets

Cited by 3 publications

References 35 publications

GRB Polarization: A Unique Probe of GRB Physics

GRB Polarization: A Unique Probe of GRB Physics

GRB Polarization: A Unique Probe of GRB Physics

Radio Linear Polarization of GRB Afterglows: Instrumental Systematics in ALMA Observations of GRB 171205A

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