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arXiv 1808.00510astro-ph.HEastro-ph.SR
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超亮超新星的星云相谱:从观测和统计性质得到的物理见解

Nebular-phase spectra of superluminous supernovae: physical insights from observational and statistical properties

Matt Nicholl, Edo Berger, Peter K Blanchard, Sebastian Gomez, Ryan Chornock

摘要:

我们研究了超亮超新星(SLSNe)在极大光之后100天内的光谱演化。我们提供了Gaia 16 apd和SN 2017 egm的新数据,并使用包含12个事件的41个光谱的更大样本分析这些数据。光谱在光变曲线峰后2-4个$e$折叠时间内变为星云状,光谱演化速率与光变曲线时间尺度相关。发射谱线与氧、钙、镁、钠和铁的众所周知的跃迁相一致。SLSNe与其他Ic型SNe的区别在于突出的O I $λ$ 7774线和较高的氧电离状态。在5000欧姆附近的铁占主导地位的区域更类似于宽线SNe Ic,而不是正常的SNe Ic。主成分分析表明,5 'eigenspectra'捕获75%的方差,而聚类分析显示,没有明确的证据多SLSN子类。线速度为5000- 8000 km/s,并显示出喷出物的分层。O I $λ$ 7774可能产生于也产生钙排放的致密内部区域,而[O I] $λ$ 6300来自更远的外部,直到300- 400天。O I $λ$ 7774和Ca II的光度表明显著的聚集,与先前的研究一致。[Ca II] $λ$ 7300/[O I] $λ$ 6300的比率有利于具有相对大质量氦核的祖细胞,可能是$\gtrsim 6$ M $_\odot$,尽管这里需要更多的建模。具有宽光变曲线的SLSNe显示出最强的[O I] $λ$ 6300,表明喷出物质量较大。我们将展示如何推断的速度,密度和电离结构指向一个中央电源。

英文摘要:

We study the spectroscopic evolution of superluminous supernovae (SLSNe) later than 100 days after maximum light. We present new data for Gaia16apd and SN2017egm, and analyse these with a larger sample comprising 41 spectra of 12 events. The spectra become nebular within 2-4 $e$-folding times after light curve peak, with the rate of spectroscopic evolution correlated to the light curve timescale. Emission lines are identified with well-known transitions of oxygen, calcium, magnesium, sodium and iron. SLSNe are differentiated from other Type Ic SNe by a prominent O I $λ$7774 line and higher-ionisation states of oxygen. The iron-dominated region around 5000 Å is more similar to broad-lined SNe Ic than to normal SNe Ic. Principal Component Analysis shows that 5 `eigenspectra' capture 75% of the variance, while a clustering analysis shows no clear evidence for multiple SLSN sub-classes. Line velocities are 5000--8000 km/s, and show stratification of the ejecta. O I $λ$7774 likely arises in a dense inner region that also produces calcium emission, while [O I] $λ$6300 comes from further out until 300--400 days. The luminosities of O I $λ$7774 and Ca II suggest significant clumping, in agreement with previous studies. Ratios of [Ca II]$λ$7300/[O I]$λ$6300 favour progenitors with relatively massive helium cores, likely $\gtrsim 6$ M$_\odot$, though more modelling is required here. SLSNe with broad light curves show the strongest [O I] $λ$6300, suggesting larger ejecta masses. We show how the inferred velocity, density and ionisation structure point to a central power source.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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