Limits on optical polarization duringt the prompt phase of GRB 140430a

0472857 - ASÚ 2017 RIV US eng J - Journal Article
Kopač, D. - Mundell, C. G. - Japelj, J. - Arnold, D. M. - Steele, I.A. - Guidorzi, C. - Dichiara, S. - Kobayashi, S. - Gomboc, A. - Harrison, R. M. - Lamb, G. P. - Melandri, A. - Smith, R. J. - Virgili, F. J. - Castro-Tirado, A.J. - Gorosabel, J. - Järvinen, A. - Sánchez-Ramírez, R. - Oates, S.R. - Jelínek, Martin
Limits on optical polarization duringt the prompt phase of GRB 140430a.
Astrophysical Journal. Roč. 813, č. 1 (2015), 1/1-1/14. ISSN 0004-637X. E-ISSN 1538-4357
Institutional support: RVO:67985815
Keywords : gamma-ray burst * GRB 140430A * polarimeters
Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
Impact factor: 5.909, year: 2015

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.-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 gammaray 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% (1 sigma). 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.
Permanent Link: http://hdl.handle.net/11104/0270081