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arXiv 1903.09262astro-ph.HE
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ZTF18aalrxas:一个来自非常扩展的低质量祖星的IIb型超新星

ZTF18aalrxas: A Type IIb Supernova from a very extended low-mass progenitor

C. Fremling, H. Ko, A. Dugas, M. Ergon, J. Sollerman, A. Bagdasaryan, C. Barbarino, J. Belicki, E. Bellm, N. Blagorodnova, K. De, R. Dekany, S. Frederick, A. Ga… 展开作者

C. Fremling, H. Ko, A. Dugas, M. Ergon, J. Sollerman, A. Bagdasaryan, C. Barbarino, J. Belicki, E. Bellm, N. Blagorodnova, K. De, R. Dekany, S. Frederick, A. Gal-Yam, D. A. Goldstein, Z. Golkhou, M. Graham, M. Kasliwal, M. Kowalski, S. R. Kulkarni, T. Kupfer, R. R. Laher, F. J. Masci, A. A. Miller, J. D. Neill, D. A. Perley, U. D. Rebbapragada, R. Riddle, B. Rusholme, S. Schulze, R. M. Smith, L. Tartaglia, Lin Yan, Y. Yao

摘要:

我们研究了ZTF 18 aalrxas,一个双峰IIb型核心坍缩超新星(SN)在Zwicky瞬态设施(ZTF)的科学验证过程中发现的。发现ZTF 18 aalrxas时,光辐射仍在向最初的冷却峰值(2天内为0.7等)上升。我们的观测包括多波段(紫外,光学)光变曲线,和光谱跨越从$\approx0.7$ d到$\approx180$ d过去的爆炸。我们使用基于Monte-Carlo的非局部热力学平衡(NLTE)模型,该模型精确地再现了$\rm ^{56}Ni$供电的辐射热光变曲线和我们的星云光谱。该模型用于约束SN的合成放射性镍质量(0.17 $\mathrm{M}_{\odot}$)和总喷出物质量(1.7 $\mathrm{M}_{\odot}$)。使用半解析扩展包络模型来模拟冷却排放,以约束爆炸时的祖半径($790-1050$ $\mathrm{R}_{\odot}$)。我们的星云光谱显示出与致密的星周介质(CSM)相互作用的迹象,并对这一光谱进行建模和分析,以约束在祖星包层中的氧喷射量($0.3-0.5$ $\mathrm{M}_{\odot}$)和氢总质量($\approx0.15$ $\mathrm{M}_{\odot}$)。ZTF 18 aalrxas的氧质量与低($12-13$ $\mathrm{M}_{\odot}$)零年龄主序列质量祖细胞一致。ZTF 18 aalrxas的光变曲线和光谱与大质量单星SN IIb型祖先模型不一致。低质量的扩展的氢信封的存在下,一个密集的CSM的存在下,派生的喷出物的质量,和后期的氧气排放都可以在一个二元模型的情况下解释。

英文摘要:

We investigate ZTF18aalrxas, a double-peaked Type IIb core-collapse supernova (SN) discovered during science validation of the Zwicky Transient Facility (ZTF). ZTF18aalrxas was discovered while the optical emission was still rising towards the initial cooling peak (0.7 mag over 2 days). Our observations consist of multi-band (UV, optical) light-curves, and optical spectra spanning from $\approx0.7$ d to $\approx180$ d past the explosion. We use a Monte-Carlo based non-local thermodynamic equilibrium (NLTE) model, that simultanously reproduces both the $\rm ^{56}Ni$ powered bolometric light curve and our nebular spectrum. This model is used to constrain the synthesized radioactive nickel mass (0.17 $\mathrm{M}_{\odot}$) and the total ejecta mass (1.7 $\mathrm{M}_{\odot}$) of the SN. The cooling emission is modeled using semi-analytical extended envelope models to constrain the progenitor radius ($790-1050$ $\mathrm{R}_{\odot}$) at the time of explosion. Our nebular spectrum shows signs of interaction with a dense circumstellar medium (CSM), and this spetrum is modeled and analysed to constrain the amount of ejected oxygen ($0.3-0.5$ $\mathrm{M}_{\odot}$) and the total hydrogen mass ($\approx0.15$ $\mathrm{M}_{\odot}$) in the envelope of the progenitor. The oxygen mass of ZTF18aalrxas is consistent with a low ($12-13$ $\mathrm{M}_{\odot}$) Zero Age Main Sequence mass progenitor. The light curves and spectra of ZTF18aalrxas are not consistent with massive single star SN Type IIb progenitor models. The presence of an extended hydrogen envelope of low mass, the presence of a dense CSM, the derived ejecta mass, and the late-time oxygen emission can all be explained in a binary model scenario.

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