Constraining the Source of the High-velocity Ejecta in Type Ia SN 2019ein
Constraining the Source of the High-velocity Ejecta in Type Ia SN 2019ein
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DOI：
10.3847/1538-4357/ab8e3f
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发表时间：
2020-03
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通讯作者：
C. Pellegrino;D. Howell;S. Sarbadhicary;J. Burke;D. Hiramatsu;C. McCully;P. Milne;J. Andrews;P. Brown;L. Chomiuk;E. Hsiao;D. Sand;M. Shahbandeh;N. Smith;S. Valenti;J. Vink'o;J. Wheeler;S. Wyatt;Y. Yang
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作者：
C. Pellegrino;D. Howell;S. Sarbadhicary;J. Burke;D. Hiramatsu;C. McCully;P. Milne;J. Andrews;P. Brown;L. Chomiuk;E. Hsiao;D. Sand;M. Shahbandeh;N. Smith;S. Valenti;J. Vink'o;J. Wheeler;S. Wyatt;Y. Yang
我们给出了SN2019ein的多波长光度和光谱观测结果，SN2019ein是在附近星系NGC5353中发现的一颗高速Ia型超新星(SNIa)，探测极限为两天。SN2019ein显示出SNIa中最高的测量膨胀速度，在峰值亮度前14天，Si II的最小吸收蓝移了24,000公里的S−1。更不同寻常的是，我们观察到P天鹅座剖面的发射成分在B波段最大光之前蓝移了10,000公里以上的S−1。这一蓝移在28个其他SNE Ia的样本中是最高的之一，在我们最早的光谱时代是最大的，随后向最大光强方向减小。我们讨论了可能的前驱系统和爆炸机制，可以解释这些极端的吸收和发射速度。在B波段最大光强之前14天开始的射电观测，在SN 2019ein的位置没有探测到，这排除了共生前驱系统、大多数快速光学厚吸积风模型和半径处光学薄质量壳的可能性。将我们的谱与其他高速SNE Ia的模型和观测结果进行比较，我们发现SN2019ein很好地符合延迟爆轰爆炸。我们认为，高发射速度可能是非对称爆炸中抛射物混合引起的丰度增强的结果，或者是早期抛射物光球层的光学深度效应的结果。这些发现可能为高速SNE Ia之间的共同爆炸机制和抛射几何形状提供证据。
We present multiwavelength photometric and spectroscopic observations of SN 2019ein, a high-velocity Type Ia supernova (SN Ia) discovered in the nearby galaxy NGC 5353 with a two-day nondetection limit. SN 2019ein exhibited some of the highest measured expansion velocities of any SN Ia, with a Si ii absorption minimum blueshifted by 24,000 km s−1 at 14 days before peak brightness. More unusually, we observed the emission components of the P Cygni profiles to be blueshifted upward of 10,000 km s−1 before B-band maximum light. This blueshift, among the highest in a sample of 28 other SNe Ia, is greatest at our earliest spectroscopic epoch and subsequently decreases toward maximum light. We discuss possible progenitor systems and explosion mechanisms that could explain these extreme absorption and emission velocities. Radio observations beginning 14 days before B-band maximum light yield nondetections at the position of SN 2019ein, which rules out symbiotic progenitor systems, most models of fast optically thick accretion winds, and optically thin shells of mass at radii . Comparing our spectra to models and observations of other high-velocity SNe Ia, we find that SN 2019ein is well fit by a delayed-detonation explosion. We propose that the high emission velocities may be the result of abundance enhancements due to ejecta mixing in an asymmetric explosion, or optical depth effects in the photosphere of the ejecta at early times. These findings may provide evidence for common explosion mechanisms and ejecta geometries among high-velocity SNe Ia.