LIMITS ON OPTICAL POLARIZATION DURING THE PROMPT PHASE OF GRB 140430A

Journal Article · Sun Nov 01 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/813/1/1· OSTI ID:22521979

Kopac, D.; Mundell, C. G.; Arnold, D. M.; Steele, I. A.; Kobayashi, S.; Lamb, G. P.; Smith, R. J.; Virgili, F. J. ^[1]; Japelj, J.; Gomboc, A. ^[2]; Guidorzi, C.; Dichiara, S. ^[3]; Harrison, R. M. ^[4]; Melandri, A. ^[5]; Castro-Tirado, A. J.; Gorosabel, J.; Sánchez-Ramírez, R.; Oates, S. R. ^[6]; Järvinen, A. ^[7]

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1. Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool, L3 5RF (United Kingdom)
2. Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia)
3. Department of Physics and Earth Sciences, University of Ferrara, via Saragat 1, I-44122, Ferrara (Italy)
4. Department of Astrophysics, School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel)
5. INAF—Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy)
6. Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomia s/n, E-18008 Granada (Spain)
7. AIP—Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)

Gamma-ray burst GRB 140430A was detected by the Swift satellite and observed promptly with the imaging polarimeter RINGO3 mounted on the Liverpool Telescope, with observations beginning while the prompt γ-ray emission was still ongoing. In this paper, we present densely sampled (10-s temporal resolution) early optical light curves (LCs) in 3 optical bands and limits to the degree of optical polarization. We compare optical, X-ray, and gamma-ray properties and present an analysis of the optical emission during a period of high-energy flaring. The complex optical LC cannot be explained merely with a combination of forward and reverse shock emission from a standard external shock, implying additional contribution of emission from internal shock dissipation. We estimate an upper limit for time averaged optical polarization during the prompt phase to be as low as P < 12% (1σ). This suggests that the optical flares and early afterglow emission in this GRB are not highly polarized. Alternatively, time averaging could mask the presence of otherwise polarized components of distinct origin at different polarization position angles.

• OSTI ID: 22521979
• Journal Information: Astrophysical Journal, Vol. 813, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AFTERGLOW
COMPARATIVE EVALUATIONS
COSMIC GAMMA BURSTS
DIAGRAMS
GAMMA RADIATION
PHOTON EMISSION
POLARIMETRY
POLARIZATION
RESOLUTION
SATELLITES
STELLAR FLARES
TELESCOPES
VISIBLE RADIATION
X RADIATION