ASYMMETRIES in SN 2014J NEAR MAXIMUM LIGHT REVEALED THROUGH SPECTROPOLARIMETRY

Amber L. Porter; Mark D. Leising; G. Grant Williams; Peter Milne; Paul Smith; Nathan Smith; Christopher Bilinski; Jennifer L. Hoffman; Leah Huk; Douglas C. Leonard

doi:10.3847/0004-637X/828/1/24

ASYMMETRIES in SN 2014J NEAR MAXIMUM LIGHT REVEALED THROUGH SPECTROPOLARIMETRY

Amber L. Porter, Mark D. Leising, G. Grant Williams, Peter Milne, Paul Smith, Nathan Smith, Christopher Bilinski, Jennifer L. Hoffman, Leah Huk, Douglas C. Leonard

Research output: Contribution to journal › Article › peer-review

18 Scopus citations

Abstract

We present spectropolarimetric observations of the nearby Type Ia supernova SN 2014J in M82 over six epochs: +0, +7, +23, +51, +77, +109, and +111 days with respect to B-band maximum. The strong continuum polarization, which is constant with time, shows a wavelength dependence unlike that produced by linear dichroism in Milky Way dust. The observed polarization may be due entirely to interstellar dust or include a circumstellar scattering component. We find that the polarization angle aligns with the magnetic field of the host galaxy, arguing for an interstellar origin. Additionally, we confirm a peak in polarization at short wavelengths that would imply R_V < 2 along the light of sight, in agreement with earlier polarization measurements. For illustrative purposes, we include a two-component fit to the continuum polarization of our +51-day epoch that combines a circumstellar scattering component with interstellar dust where scattering can account for over half of the polarization at 4000 Å. Upon removal of the interstellar polarization signal, SN 2014J exhibits very low levels of continuum polarization. Asymmetries in the distribution of elements within the ejecta are visible through moderate levels of time-variable polarization in accordance with the Si II λ6355 absorption line. At maximum light, the line polarization reaches ∼0.6% and decreases to ∼0.4% 1 week later. This feature also forms a loop on the q_RSP-u_RSP plane, illustrating that the ion does not have an axisymmetric distribution. The observed polarization properties suggest that the explosion geometry of SN 2014J is generally spheroidal with a clumpy distribution of silicon.

Original language	English
Article number	24
Journal	Astrophysical Journal
Volume	828
Issue number	1
DOIs	https://doi.org/10.3847/0004-637X/828/1/24
State	Published - Sep 1 2016
Externally published	Yes

Funding

This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration and the VizieR catalog access tool, CDS, Strasbourg, France. D.C.L. acknowledges support from NSF grants AST-1009571 and AST-1210311, under which part of this research was carried out. This research was also supported by NSF grants AST-1210599 (UA) and AST-1210372 (U. Denver). Some observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.

Funders	Funder number
NASA/IPAC
National Science Foundation	1515559, AST-1210599, AST-1009571, AST-1210311
Smithsonian Institution
Directorate for Mathematical and Physical Sciences	1210372, 1210599, 1009571, 1210311
National Aeronautics and Space Administration
University of Arizona
University of Akron	AST-1210372
Chinese Diabetes Society

Keywords

polarization
supernovae: general
supernovae: individual (SN 2014J)

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10.3847/0004-637X/828/1/24

Cite this

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title = "ASYMMETRIES in SN 2014J NEAR MAXIMUM LIGHT REVEALED THROUGH SPECTROPOLARIMETRY",

abstract = "We present spectropolarimetric observations of the nearby Type Ia supernova SN 2014J in M82 over six epochs: +0, +7, +23, +51, +77, +109, and +111 days with respect to B-band maximum. The strong continuum polarization, which is constant with time, shows a wavelength dependence unlike that produced by linear dichroism in Milky Way dust. The observed polarization may be due entirely to interstellar dust or include a circumstellar scattering component. We find that the polarization angle aligns with the magnetic field of the host galaxy, arguing for an interstellar origin. Additionally, we confirm a peak in polarization at short wavelengths that would imply RV < 2 along the light of sight, in agreement with earlier polarization measurements. For illustrative purposes, we include a two-component fit to the continuum polarization of our +51-day epoch that combines a circumstellar scattering component with interstellar dust where scattering can account for over half of the polarization at 4000 {\AA}. Upon removal of the interstellar polarization signal, SN 2014J exhibits very low levels of continuum polarization. Asymmetries in the distribution of elements within the ejecta are visible through moderate levels of time-variable polarization in accordance with the Si II λ6355 absorption line. At maximum light, the line polarization reaches ∼0.6% and decreases to ∼0.4% 1 week later. This feature also forms a loop on the qRSP-uRSP plane, illustrating that the ion does not have an axisymmetric distribution. The observed polarization properties suggest that the explosion geometry of SN 2014J is generally spheroidal with a clumpy distribution of silicon.",

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AU - Porter, Amber L.

AU - Leising, Mark D.

AU - Williams, G. Grant

AU - Milne, Peter

AU - Smith, Paul

AU - Smith, Nathan

AU - Bilinski, Christopher

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AU - Huk, Leah

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AB - We present spectropolarimetric observations of the nearby Type Ia supernova SN 2014J in M82 over six epochs: +0, +7, +23, +51, +77, +109, and +111 days with respect to B-band maximum. The strong continuum polarization, which is constant with time, shows a wavelength dependence unlike that produced by linear dichroism in Milky Way dust. The observed polarization may be due entirely to interstellar dust or include a circumstellar scattering component. We find that the polarization angle aligns with the magnetic field of the host galaxy, arguing for an interstellar origin. Additionally, we confirm a peak in polarization at short wavelengths that would imply RV < 2 along the light of sight, in agreement with earlier polarization measurements. For illustrative purposes, we include a two-component fit to the continuum polarization of our +51-day epoch that combines a circumstellar scattering component with interstellar dust where scattering can account for over half of the polarization at 4000 Å. Upon removal of the interstellar polarization signal, SN 2014J exhibits very low levels of continuum polarization. Asymmetries in the distribution of elements within the ejecta are visible through moderate levels of time-variable polarization in accordance with the Si II λ6355 absorption line. At maximum light, the line polarization reaches ∼0.6% and decreases to ∼0.4% 1 week later. This feature also forms a loop on the qRSP-uRSP plane, illustrating that the ion does not have an axisymmetric distribution. The observed polarization properties suggest that the explosion geometry of SN 2014J is generally spheroidal with a clumpy distribution of silicon.

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ASYMMETRIES in SN 2014J NEAR MAXIMUM LIGHT REVEALED THROUGH SPECTROPOLARIMETRY

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Keywords

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