Type II supernova spectral diversity. II. Spectroscopic and photometric correlations
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We present an analysis of observed trends and correlations between a large range of spectral and photometric parameters of more than 100 type II supernovae (SNe II), during the photospheric phase. We define a common epoch for all SNe of 50 days post-explosion, where the majority of the sample is likely to be under similar physical conditions. Several correlation matrices are produced to search for interesting trends between more than 30 distinct light-curve and spectral properties that characterize the diversity of SNe II. Overall, SNe with higher expansion velocities are brighter, have more rapidly declining light curves, shorter plateau durations, and higher Ni-56 masses. Using a larger sample than previous studies, we argue that "Pd"-the plateau duration from the transition of the initial to "plateau" decline rates to the end of the "plateau"-is a better indicator of the hydrogen envelope mass than the traditionally used optically thick phase duration (OPTd: explosion epoch to end of plateau). This argument is supported by the fact that Pd also correlates with ,S-3, the light-curve decline rate at late times: lower Pd values correlate with larger ,S-3 decline rates. Large ,S-3 decline rates are likely related to lower envelope masses, which enables gamma-ray escape. We also find a significant anticorrelation between Pd and ,S-2 (the plateau decline rate), confirming the long standing hypothesis that faster declining SNe II (SNe IIL) are the result of explosions with lower hydrogen envelope masses and therefore have shorter Pd values.
"Millennium Center for Supernova Science" of the Iniciativa Cientfica Milenio del Ministerio Economa, Fomento y Turismo de Chile P10-064-F Millennium Institute of Astrophysics (MAS) IC120009 Danish Agency for Science and Technology and Innovation realized through a Sapere Aude Level 2 grant CSP by the NSF AST0306969 AST0908886 AST0607438 AST1008343 EU/ FP7-ERC grant 615929 VILLUM FONDEN 13261
Artículo de publicación ISI
Quote ItemThe Astrophysical Journal, 850:90 (25pp), 2017 November 20
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