AI 中文总结
研究对年轻Ia型超新星SN 2021fxy爆炸后几天进行光学观测，聚焦其高速特征。给出其光度、镍质量等数据，发现早期光谱中中等质量元素HVFs与光球成分分离，速度幂律演化比预期浅，为Ia型超新星爆炸物理提供约束。
AI 中文摘要
我们展示了对年轻Ia型超新星（SN Ia）SN 2021fxy在爆炸后几天内获得的光学观测结果，重点关注其显著的高速特征（HVFs）。它达到了B波段最大值$M_{\rm max}(B)= -19.36\pm0.31$星等，对应于约$1.3\times10^{43}~\rm{erg~s^{-1}}$的热光度，合成的$^{56}$Ni质量为$0.58\pm0.14$ $M_{\odot}$。早期光谱显示出中等质量元素的强HVFs，与光球成分显著分离。特别是，Si II $\lambda6355$ HVFs的速度遵循幂律演化（$\beta \approx 0.1$），比在同源膨胀下假设的$n = 10$密度分布预期的光球速度演化（$\beta \approx 0.22$）更浅。这种行为与HVFs在至少部分与大量外层抛射物解耦的固有抛射物结构中形成一致，为Ia型超新星的爆炸物理提供了可能的约束。
英文摘要
We present optical observations on the young type Ia supernova (SN Ia) SN 2021fxy obtained within a few days after the explosion, with a focus on its prominent high-velocity features (HVFs). It reached a $B$-band maximum of $M_{\rm max}(B) = -19.36\pm0.31$ mag, corresponding to a bolometric luminosity of $\sim 1.3\times10^{43}~\rm{erg~s^{-1}}$ with a synthesized $^{56}$Ni mass of $0.58\pm0.14$ M$_{\odot}$. The early spectra exhibit strong HVFs of intermediate-mass elements that are significantly detached from the photospheric components. In particular, the velocity of the Si II $\lambda6355$ HVFs follows a power-law evolution ($β\approx 0.1$), shallower than the expected photospheric velocity evolution expected for an assumed $n=10$ density profile ($β\approx 0.22$) under homologous expansion. This behavior is consistent with the HVFs forming in intrinsic ejecta structures at least partially decoupled from the bulk outer ejecta, providing a possible constraint on the explosion physics of SNe Ia.
Comments19 pages, 9 figures, accepted for publication in ApJ
