TY - JOUR
T1 - Time-resolved Polarimetry of the Superluminous SN 2015bn with the Nordic Optical Telescope
AU - Leloudas, Giorgos
AU - Maund, Justyn R.
AU - Gal-Yam, Avishay
AU - Pursimo, Tapio
AU - Hsiao, Eric
AU - Malesani, Daniele
AU - Patat, Ferdinando
AU - de Ugarte Postigo, Ugarte Postigo, Antonio
AU - Sollerman, Jesper
AU - Stritzinger, Maximilian D.
AU - Wheeler, J. Craig
N1 - We are grateful to Cosimo Inserra and Mattia Bulla for valuable comments and for sending us integrated V-band polarization values from their spectropolarimetry. A.G.-Y. is supported by the EU/FP7 via ERC grant No. 307260, the Quantum Universe I-Core program by the Israeli Committee for Planning and Budgeting, and the ISF; and by Kimmel and YeS awards. D.M. is partly supported by the Instrument Center for Danish Astrophysics (IDA). A.d.U.P. acknowledges support from a Ramn y Cajal fellowship and project AYA2014-58381-P. M.S. is supported in part by a Sapere Aude Level 2 grant funded by the Danish Agency for Science and Technology and Innovation and by a grant from the Villum foundation. The research of J.C.W. is supported in part by NSF AST-1109801. Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofísica de Canarias.
PY - 2017/3/1
Y1 - 2017/3/1
N2 - We present imaging polarimetry of the superluminous supernova SN 2015bn, obtained over nine epochs between −20 and +46 days with the Nordic Optical Telescope. This was a nearby, slowly evolving Type I superluminous supernova that has been studied extensively and for which two epochs of spectropolarimetry are also available. Based on field stars, we determine the interstellar polarization in the Galaxy to be negligible. The polarization of SN 2015bn shows a statistically significant increase during the last epochs, confirming previous findings. Our well-sampled imaging polarimetry series allows us to determine that this increase (from ~0.54% to gsim1.10%) coincides in time with rapid changes that took place in the optical spectrum. We conclude that the supernova underwent a "phase transition" at around +20 days, when the photospheric emission shifted from an outer layer, dominated by natal C and O, to a more aspherical inner core, dominated by freshly nucleosynthesized material. This two-layered model might account for the characteristic appearance and properties of Type I superluminous supernovae.
AB - We present imaging polarimetry of the superluminous supernova SN 2015bn, obtained over nine epochs between −20 and +46 days with the Nordic Optical Telescope. This was a nearby, slowly evolving Type I superluminous supernova that has been studied extensively and for which two epochs of spectropolarimetry are also available. Based on field stars, we determine the interstellar polarization in the Galaxy to be negligible. The polarization of SN 2015bn shows a statistically significant increase during the last epochs, confirming previous findings. Our well-sampled imaging polarimetry series allows us to determine that this increase (from ~0.54% to gsim1.10%) coincides in time with rapid changes that took place in the optical spectrum. We conclude that the supernova underwent a "phase transition" at around +20 days, when the photospheric emission shifted from an outer layer, dominated by natal C and O, to a more aspherical inner core, dominated by freshly nucleosynthesized material. This two-layered model might account for the characteristic appearance and properties of Type I superluminous supernovae.
UR - http://www.scopus.com/inward/record.url?scp=85014970638&partnerID=8YFLogxK
U2 - https://doi.org/10.3847/2041-8213/aa6157
DO - https://doi.org/10.3847/2041-8213/aa6157
M3 - مقالة
SN - 2041-8205
VL - 837
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - 14
ER -