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arXiv 1404.0650astro-ph.HEastro-ph.SR
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利用Swift UVOT对超克拉塞卡质量Ia型超新星候选者的紫外观测

Ultraviolet Observations of Super-Chandrasekhar Mass Type Ia Supernova Candidates with Swift UVOT

Peter J. Brown, Paul Kuin, Richard Scalzo, Michael Smitka, Massimiliano de Pasquale, Stephen Holland, Kevin Krisciunas, Peter Milne, Lifan Wang

摘要:

在Ia型超新星(SNe~Ia)中,存在着一类过亮天体,它们的喷出物质量被推断为大于经典的克拉塞卡质量。我们提出并讨论了紫外/光学光度的光变曲线,颜色,绝对星等,和光谱的三个候选人的超拉塞卡质量SNe-2009dc,2011aa,和2012dn-观察与斯威夫特紫外/光学望远镜。Ia型超新星的光变曲线位于宽端,SN~2011aa的光变曲线是有史以来观测到的最宽的光变曲线。我们发现这三个超新星都有非常蓝的颜色,这可能提供了一种从宇宙学分析中排除这些过度发光的SNe的方法,尽管它们与最蓝的"正常" SNe Ia有一些重叠。这三颗超新星的紫外绝对星等都比正常的和宽的Ia型超新星过亮,但2011 aa和2012 dn的光学光度并不比正常的Ia型超新星过亮。SNe 2011 aa和2012 dn在UVOT范围(1600 - 6000埃)的积分亮度曲线只有SN~2009 dc的一半亮,这意味着56 Ni产额较小。虽然不足以强烈影响辐射热通量,但早期的中紫外线通量在早期做出了重大贡献。SNe 2009dc和2012dn的中紫外光谱中的强光谱特征表明,更高的温度和更低的不透明度是紫外线过量的原因,而不是来自激波相互作用的热的、光滑的黑体。需要进一步的工作来确定SNe 2011aa和2012dn的喷出物和56Ni质量,并充分解释它们的高紫外光度。

英文摘要:

Among Type Ia supernovae (SNe~Ia) exist a class of overluminous objects whose ejecta mass is inferred to be larger than the canonical Chandrasekhar mass. We present and discuss the UV/optical photometric light curves, colors, absolute magnitudes, and spectra of three candidate Super-Chandrasekhar mass SNe--2009dc, 2011aa, and 2012dn--observed with the Swift Ultraviolet/Optical Telescope. The light curves are at the broad end for SNe Ia, with the light curves of SN~2011aa being amongst the broadest ever observed. We find all three to have very blue colors which may provide a means of excluding these overluminous SNe from cosmological analysis, though there is some overlap with the bluest of "normal" SNe Ia. All three are overluminous in their UV absolute magnitudes compared to normal and broad SNe Ia, but SNe 2011aa and 2012dn are not optically overluminous compared to normal SNe Ia. The integrated luminosity curves of SNe 2011aa and 2012dn in the UVOT range (1600-6000 Angstroms) are only half as bright as SN~2009dc, implying a smaller 56Ni yield. While not enough to strongly affect the bolometric flux, the early time mid-UV flux makes a significant contribution at early times. The strong spectral features in the mid-UV spectra of SNe 2009dc and 2012dn suggest a higher temperature and lower opacity to be the cause of the UV excess rather than a hot, smooth blackbody from shock interaction. Further work is needed to determine the ejecta and 56Ni masses of SNe 2011aa and 2012dn and fully explain their high UV luminosities.

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