SN 2019ein: New Insights into the Similarities and Diversity among High-velocity Type Ia Supernovae-猫眼课题宝

DOI：

10.3847/1538-4357/ab8236

发表时间：

2019-08

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

M. Kawabata;K. Maeda;M. Yamanaka;T. Nakaoka;K. Kawabata;R. Adachi;H. Akitaya;U. Burgaz;H. Hanayama;Takashi Horiuchi;R. Hosokawa;K. Iida;F. Imazato;K. Isogai;Jiachen Jiang;Noriyuki Katoh;Hiroki Kimura;M. Kino;D. Kuroda;H. Maehara;K. Matsubayashi;K. Morihana;K. Murata;T. Nagao;M. Niwano;D. Nogami;M. Oeda;Tatsuharu Ono;H. Onozato;M. Otsuka;Tomoki Saito;M. Sasada;K. Shiraishi;Haruki Sugiyama;K. Taguchi;J. Takahashi;K. Takagi;S. Takagi;M. Takayama;Miyako Tozuka;K. Sekiguchi

我们提出了Ia型超新星（SN）2019 ein的光学观测，从估计爆炸日期后两天开始。光谱和光变曲线表明，SN 2019 ein属于高速宽线型，光变曲线衰减较快（Δm15（B）= 1.36 ± 0.02 mag），上升时间较短（15.37 ± 0.55天）。Si ii λ6355的速度与光球成分有关，但与分离的高速特征无关，在B波段最大值出现前12天达到20，000 km s−1。然而，线速度非常迅速而平稳地向最亮处下降，达到13，000 km s−1，这在HV SNe中相对较低。这表明HV超新星Ia的光谱演化速度不仅与最大光时的速度相关，而且与光变曲线下降率相关，就像正常速度（NV）超新星Ia的情况一样。光谱合成模拟表明，在> 17，000 km s-1的最外层，O-Ne-C燃烧层至少延伸到25，000 km s-1，并且在30，000 km s-1以下没有未燃烧的碳;这些特性在很大程度上与延迟爆轰方案相一致，并且与原型HV SN 2002 bo共享，尽管Δm15（B）。这一结构与已被充分研究的NV SN 2011 fe的结构截然不同。我们认为，~（56）Ni的质量（或Δ m ~（15））与O-Ne-C燃烧层范围的关系，对HV和NV SNe的爆炸机理提供了重要的制约。

We present optical observations of the Type Ia supernova (SN) 2019ein, starting two days after the estimated explosion date. The spectra and light curves show that SN 2019ein belongs to a high-velocity (HV) and broad-line group with a relatively rapid decline in the light curves (Δm15(B) = 1.36 ± 0.02 mag) and a short rise time (15.37 ± 0.55 days). The Si ii λ6355 velocity, associated with a photospheric component but not with a detached high-velocity feature, reached ∼20,000 km s−1 12 days before the B-band maximum. The line velocity, however, decreased very rapidly and smoothly toward maximum light, to ∼13,000 km s−1, which is relatively low among HV SNe. This indicates that the speed of the spectral evolution of HV SNe Ia is correlated with not only the velocity at maximum light, but also the light-curve decline rate, as is the case for normal-velocity (NV) SNe Ia. Spectral synthesis modeling shows that the outermost layer at >17,000 km s−1 is well described by an O–Ne–C burning layer extending to at least 25,000 km s−1, and there is no unburnt carbon below 30,000 km s−1; these properties are largely consistent with the delayed detonation scenario and are shared with the prototypical HV SN 2002bo despite the large difference in Δm15(B). This structure is strikingly different from that derived for the well-studied NV SN 2011fe. We suggest that the relation between the mass of 56Ni (or Δm15) and the extent of the O–Ne–C burning layer provides an important constraint on the explosion mechanism(s) of HV and NV SNe.

SN 2019ein: New Insights into the Similarities and Diversity among High-velocity Type Ia Supernovae

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