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| Paper: |
Optical Linear Polarization in the Case of Two Supernovae
Associated to X-ray Flashes: XRF060218/SN2006aj and XRF080109/SN2008D |
| Volume: |
449, Astronomical Polarimetry 2008: Science from Small to Large Telescopes |
| Page: |
421 |
| Authors: |
Gorosabel, J.; de Postigo, A. U.; Castro-Tirado, A. J.; Jel'inek, M.; Larionov; Guziy, S.; Augusteijn, T.; Fynbo, J.; Hjorth, J.; Malesani, D.; Xu, D.; Ferrero, P.; Kann, A.; Klose, S.; Rossi, A.; Llorente, A.; Madrid, J. P. |
| Abstract: |
We present the polarization monitoring carried out for two SNe
associated with GRBs: XRF060218/SN2006aj and XRF080109/SN2008D.
For XRF060218/SN2006aj we measured a mean polarization of P∼4%
at 2.6-5.6 days after the X-ray event. This is the highest
polarization value ever measured for a supernova. We derived the
intrinsic polarization of XRF080109/SN2008D, assuming that the last
polarization detection is due to the host galaxy. The resulting
XRF060218/SN2006aj intrinsic polarization decayed as t–2,
similarly as the one reported for SN2004dj. This decay can be
explained by a circularization of the expansion geometry.
Surprisingly the XRF060218/SN2006aj polarization position angle
displayed a ≈ 100° rotation when we compare data taken
before and after the light curve peak. On the other hand,
XRF080109/SN2008D showed polarization values in the range
0.7–1.6%. A statistical analysis of the data distribution on the
Stokes plane strongly suggests that XRF080109/SN2008D showed
intrinsic variable polarization. Assuming that the Ib-type SN2007uy
(another SN simultaneously imaged in the same host of
XRF080109/SN2008D) is constant in the Stokes plane, then the Stokes
parameters of XRF080109/ SN2008D evolve approximately on a straight
line as expected for an axisymmetric expansion. These two examples
illustrate how to obtain geometric information without resolving the
emitting source. |
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