Light Curves of Type II Supernovae

Linking supernovae to their progenitors is a powerful method for furthering our understanding of the physical origin of their observed differences while at the same time testing stellar evolution theory. In this second study of a series of three papers where we characterise type II supernovae (SNe II) to understand their diversity, we derive progenitor properties (initial and ejecta masses and radius), explosion energy, and 56Ni mass and its degree of mixing within the ejecta for a large sample of SNe II. This dataset was obtained by the Carnegie Supernova Project-I and is characterised by a high cadence of SNe II optical and near-infrared light curves and optical spectra that were homogeneously observed and processed. A large grid of hydrodynamical models and a fitting procedure based on Markov chain Monte Carlo methods were used to fit the bolometric light curve and the evolution of the photospheric velocity of 53 SNe II. We infer ejecta masses of between 7.9 and 14.8 M⊙, explosion energies between 0.15 and 1.40 foe, and 56Ni masses between 0.006 and 0.069 M⊙. We define a subset of 24 SNe (the ‘gold sample’) with well-sampled bolometric light curves and expansion velocities for which we consider the results more robust. Most SNe II in the gold sample (∼88%) are found with ejecta masses in the range of ∼8−10 M⊙, coming from low zero-age main-sequence masses (9−12 M⊙). The modelling of the initial-mass distribution of the gold sample gives an upper mass limit of 21.3$ ^{+3.8}_{-0.4} $ M⊙ and a much steeper distribution than that for a Salpeter massive-star initial mass function (IMF). This IMF incompatibility is due to the large number of low-mass progenitors found – when assuming standard stellar evolution. This may imply that high-mass progenitors lose more mass during their lives than predicted. However, a deeper analysis of all stellar evolution assumptions is required to test this hypothesis.

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“…Detailed reviews can be found in the literature (e.g. Arnett 1996;Woosley et al 2002;Zampieri 2017).…”

Section: Sn II Physicsmentioning

confidence: 99%

Type II supernovae from the Carnegie Supernova Project-I

Martínez

Bersten

Anderson

et al. 2022

A&A

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“…. For stars that explode as supergiants, the rise timescale is governed by the cooling of the shock-heated photosphere and the fading timescale is governed by the gradual recombination of the ejecta (Arnett 1980;Weiler 2003;Zampieri 2017). For stars that explode in a compact state (stripped-envelope Wolf-Rayet stars and white dwarfs), the emission from the shock breakout and cooling is primarily at X-ray wavelengths and the rise and fall in the optical band are instead dominated by the dispersal of heat from newly-synthesized radioactive elements through the expanding ejecta (Arnett 1982).…”

mentioning

confidence: 99%

Real-time discovery of AT2020xnd: a fast, luminous ultraviolet transient with minimal radioactive ejecta

Perley

Yao

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The many unusual properties of the enigmatic AT2018cow suggested that at least some subset of the empirical class of fast blue optical transients (FBOTs) represents a genuinely new astrophysical phenomenon. Unfortunately, the intrinsic rarity and fleeting nature of these events have made it difficult to identify additional examples early enough to acquire the observations necessary to constrain theoretical models. We present here the Zwicky Transient Facility discovery of AT2020xnd (ZTF20acigmel, the “Camel”) at z = 0.243, the first unambiguous AT2018cow analog to be found and confirmed in real time. AT2018cow and AT2020xnd share all key observational properties: a fast optical rise, sustained high photospheric temperature, absence of a second peak attributable to ejection of a radioactively-heated stellar envelope, extremely luminous radio, millimetre, and X-ray emission, and a dwarf-galaxy host. This supports the argument that AT2018cow-like events represent a distinct phenomenon from slower-evolving radio-quiet supernovae, likely requiring a different progenitor or a different central engine. The sample properties of the four known members of this class to date disfavour tidal disruption models but are consistent with the alternative model of an accretion powered jet following the direct collapse of a massive star to a black hole. Contextual filtering of alert streams combined with rapid photometric verification using multi-band imaging provides an efficient way to identify future members of this class, even at high redshift.

show abstract

“…Detailed reviews can be found in the literature (e.g. Arnett 1996;Woosley et al 2002;Zampieri 2017).…”

Section: Sn II Physicsmentioning

confidence: 99%

Type II supernovae from the Carnegie Supernova Project-I. II. Physical parameter distributions from hydrodynamical modelling

Martinez,

Bersten,

Anderson

et al. 2021

Preprint

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Linking supernovae to their progenitors is a powerful method to further our understanding of the physical origin of their observed differences, while at the same time to test stellar evolution theory. In this second study of a series of three papers where we characterise type II supernovae (SNe II) to understand their diversity, we derive progenitor properties (initial and ejecta masses, and radius), explosion energy, 56 Ni mass, and its degree of mixing within the ejecta for a large sample of SNe II. This data set was obtained by the Carnegie Supernova Project-I and is characterised by a high cadence of their optical and near-infrared light curves and optical spectra homogeneously observed and processed. A large grid of hydrodynamical models and a fitting procedure based on Markov chain Monte Carlo (MCMC) methods were used to fit the bolometric light curve and the evolution of the photospheric velocity of 53 SNe II. We infer ejecta masses between 7.9 and 14.8 M , explosion energies between 0.15 and 1.40 foe, and 56 Ni masses between 0.006 and 0.069 M . We define a subset of 24 SNe (the 'gold sample') with well-sampled bolometric light curves and expansion velocities for which we consider the results more robust. Most SNe II in the gold sample (∼88%) are found with ejecta masses in the range of ∼8−10 M , coming from low zero-age main-sequence masses (9−12 M ). The modelling of the initial-mass distribution of the gold sample gives an upper mass limit of 21.3 +3.8 −0.4 M and a much steeper distribution than that for a Salpeter massive-star initial mass function (IMF). This IMF incompatibility is due to the large number of low-mass progenitors found -when assuming standard stellar evolution. This may imply that high-mass progenitors lose more mass during their lives than predicted. However, a deeper analysis of all stellar evolution assumptions is required to test this hypothesis.

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Light Curves of Type II Supernovae

Cited by 4 publications

References 46 publications

Type II supernovae from the Carnegie Supernova Project-I

Type II supernovae from the Carnegie Supernova Project-I

Real-time discovery of AT2020xnd: a fast, luminous ultraviolet transient with minimal radioactive ejecta

Type II supernovae from the Carnegie Supernova Project-I. II. Physical parameter distributions from hydrodynamical modelling

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