The Young and Nearby Normal Type Ia Supernova 2018gv: UV-optical Observations and the Earliest Spectropolarimetry
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Author
Yang, Yi
Hoeflich, Peter
Baade, Dietrich
Maund, Justyn R.
Wang, Lifan
Brown, Peter. J.
Stevance, Heloise F.
Arcavi, Iair
Burke, Jamison
Cikota, Aleksandar
Clocchiatti, Alejandro
Gal-Yam, Avishay
Graham, Melissa. L.
Hiramatsu, Daichi
Hosseinzadeh, Griffin
Howell, D. Andrew
Jha, Saurabh W.
McCully, Curtis
Patat, Ferdinando
Sand, David. J.
Schulze, Steve
Spyromilio, Jason
Valenti, Stefano
Vinkó, József

Wang, Xiaofeng

Wheeler, J. Craig
Yaron, Ofer
Zhang, Jujia

Affiliation
Univ Arizona, Steward ObservIssue Date
2020-10-09
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Yang, Y., Hoeflich, P., Baade, D., Maund, J. R., Wang, L., Brown, P. J., ... & Zhang, J. (2020). The young and nearby normal Type Ia supernova 2018gv: UV-optical observations and the earliest spectropolarimetry. The Astrophysical Journal, 902(1), 46.Journal
ASTROPHYSICAL JOURNALRights
© 2020. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
The nondetection of companion stars in SN Ia progenitor systems lends support to the notion of double-degenerate systems and explosions triggered by the merging of two white dwarfs. This very asymmetric process should lead to a conspicuous polarimetric signature. By contrast, observations consistently find very low continuum polarization as the signatures from the explosion process largely dominate over the pre-explosion configuration within several days. Critical information about the interaction of the ejecta with a companion and any circumstellar matter is encoded in the early polarization spectra. In this study, we obtain spectropolarimetry of SN 2018gv with the ESO Very Large Telescope at -13.6 days relative to theB-band maximum light, or similar to 5 days after the estimated explosion-the earliest spectropolarimetric observations to date of any SN Ia. These early observations still show a low continuum polarization (less than or similar to 0.2%) and moderate line polarization (0.30% 0.04% for the prominent Siii lambda 6355 feature and 0.85% 0.04% for the high-velocity Ca component). The high degree of spherical symmetry implied by the low-line and continuum polarization at this early epoch is consistent with explosion models of delayed detonations and is inconsistent with the merger-induced explosion scenario. The dense UV and optical photometry and optical spectroscopy within the first similar to 100 days after the maximum light indicate that SN 2018gv is a normal SN Ia with similar spectrophotometric behavior to SN 2011fe.ISSN
0004-637XEISSN
1538-4357Version
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/aba759