TY - JOUR
T1 - Record-breaking polarization from the interacting superluminous supernova 2017hcc
AU - Mauerhan, Jon C.
AU - Smith, Nathan
AU - Williams, G. Grant
AU - Smith, Paul S.
AU - Filippenko, Alexei V.
AU - Bilinski, Christopher
AU - Zheng, Wei Kang
AU - Brink, Thomas G.
AU - Hoffman, Jennifer L.
AU - Leonard, Douglas C.
AU - Milne, Peter
AU - Jeffers, Benjamin
AU - Modak, Shaunak
AU - Stegman, Samantha
AU - Zhang, Keto D.
N1 - Publisher Copyright:
© 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2024/1/1
Y1 - 2024/1/1
N2 - We present multi-epoch spectropolarimetry of Type IIn supernova SN2017hcc, 16-391 d after explosion. Continuum polarization up to 6 per cent is observed during the first epoch, making SN 2017hcc the most intrinsically polarized SN ever reported at visible wavelengths. During the first 29 d, when the polarization is strongest, the continuum polarization exhibits wavelength dependence that rises toward the blue, then becomes wavelength independent by day 45. The polarization drops rapidly during the first month, even as the flux is still climbing to peak brightness. None the less, unusually high polarization is maintained until day 68, at which point the polarization declines to levels comparable to those of previous well-studied SNe IIn. Only minor changes in position angle (PA) are measured throughout the evolution. The blue slope of the polarized continuum and polarized line emission during the first month suggests that an aspherical distribution of dust grains in pre-shock circumstellar material (CSM) is echoing the SN IIn spectrum and strongly influencing the polarization, while the subsequent decline during the wavelength-independent phase appears consistent with electron scattering near the SN/CSM interface. The persistence of the PA between these two phases suggests that the pre-existing CSM responsible for the dust scattering at early times is part of the same geometric structure as the electron-scattering region that dominates the polarization at later times. SN 2017hcc appears to be yet another, but more extreme, case of aspherical yet well-ordered CSM in Type IIn SNe, possibly resulting from pre-SN mass-loss shaped by a binary progenitor system.
AB - We present multi-epoch spectropolarimetry of Type IIn supernova SN2017hcc, 16-391 d after explosion. Continuum polarization up to 6 per cent is observed during the first epoch, making SN 2017hcc the most intrinsically polarized SN ever reported at visible wavelengths. During the first 29 d, when the polarization is strongest, the continuum polarization exhibits wavelength dependence that rises toward the blue, then becomes wavelength independent by day 45. The polarization drops rapidly during the first month, even as the flux is still climbing to peak brightness. None the less, unusually high polarization is maintained until day 68, at which point the polarization declines to levels comparable to those of previous well-studied SNe IIn. Only minor changes in position angle (PA) are measured throughout the evolution. The blue slope of the polarized continuum and polarized line emission during the first month suggests that an aspherical distribution of dust grains in pre-shock circumstellar material (CSM) is echoing the SN IIn spectrum and strongly influencing the polarization, while the subsequent decline during the wavelength-independent phase appears consistent with electron scattering near the SN/CSM interface. The persistence of the PA between these two phases suggests that the pre-existing CSM responsible for the dust scattering at early times is part of the same geometric structure as the electron-scattering region that dominates the polarization at later times. SN 2017hcc appears to be yet another, but more extreme, case of aspherical yet well-ordered CSM in Type IIn SNe, possibly resulting from pre-SN mass-loss shaped by a binary progenitor system.
KW - circumstellar matter
KW - stars: evolution
KW - supernovae: general
KW - supernovae: individual: SN 2017hcc-stars: winds, outflows
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U2 - 10.1093/mnras/stad3579
DO - 10.1093/mnras/stad3579
M3 - Article
AN - SCOPUS:85179891506
SN - 0035-8711
VL - 527
SP - 6090
EP - 6099
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -