Three-Dimensional Explosion Geometry Of Stripped-Envelope Core-Collapse Supernovae. I. Spectropolarimetric Observations

Tanaka Masaomi

Kawabata Koji S.

Hattori Takashi

Mazzali Paolo A.

Aoki Kentaro

Iye Masanori

Maeda Keiichi

Nomoto Ken'ichi

Pian Elena

Sasaki Toshiyuki

Yamanaka Masayuki

Astrophysical Journal

We study the multi-dimensional geometry of supernova (SN) explosions by means of spectropolarimetric observations of stripped-envelope SNe, i.e., SNe without a hydrogen-rich layer. We perform spectropolarimetric observations of two stripped-envelope SNe, Type Ib SN 2009jf and Type Ic SN 2009mi. Both objects show non-zero polarization at the wavelength of the strong lines. They also show a loop in the Stokes Q-U diagram, which indicates a non-axisymmetric, three-dimensional ion distribution in the ejecta. We show that five out of six stripped-envelope SNe, which have been observed spectropolarimetrically so far, show such a loop. This implies that a three-dimensional geometry is common in stripped-envelope SNe. We find that stronger lines tend to show higher polarization. This effect is not related to the geometry, and must be corrected for to compare the polarization of different lines or different objects. Even after the correction, however, there remains a dispersion of polarization degree among different objects. Such a dispersion might be caused by three-dimensional clumpy ion distributions viewed from different directions.

supernovae: general

supernovae: individual (SNe 2009jf, 2009mi)

techniques: polarimetric

Astronomy. Space sciences [ 440 ]

eng

IOP Publishing Ltd

(c) 2012. The American Astronomical Society. All rights reserved. Printed in the U.S.A.

[ISSN] 0004-637X

[DOI] 10.1088/0004-637X/754/1/63

[NCID] AA00553242

[DOI] http://dx.doi.org/10.1088/0004-637X/754/1/63