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arXiv 1111.0966astro-ph.HEastro-ph.CO
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SN 2011 fe的一个致密退化原恒星

A Compact Degenerate Primary-Star Progenitor of SN 2011fe

Joshua S. Bloom, Daniel Kasen, Ken J. Shen, Peter E. Nugent, Nathaniel R. Butler, Melissa L. Graham, D. Andrew Howell, Ulrich Kolb, Stefan Holmes, Carole Haswel… 展开作者

Joshua S. Bloom, Daniel Kasen, Ken J. Shen, Peter E. Nugent, Nathaniel R. Butler, Melissa L. Graham, D. Andrew Howell, Ulrich Kolb, Stefan Holmes, Carole Haswell, Vadim Burwitz, Juan Rodriguez, Mark Sullivan

摘要:

虽然从理论的角度来看,白矮星是Ia型超新星(SN Ia)中最有可能的主星,但许多其他候选者尚未被正式排除。沉积在任何爆炸的主包层中的冲击能量有助于早期SN亮度,并且由于这种辐射能量在爆炸后因膨胀而退化,因此扩散光度取决于初始主半径。我们提出了一个新的Ia 2011 fe附近超新星的不可探测极限,该极限似乎是在爆炸后4小时获得的,这使得我们能够直接约束初始主半径R_p。结合未探测到的静止X射线对应物和推断的合成Ni质量,我们表明R_p <~ 0.02 R_sun(比先前推断的小5倍),初级粒子的平均密度必须大于10,000 gm cm^{-3},有效温度必须小于几× 10^5 K。这排除了氢燃烧的主序星和巨星。在构造氦燃烧主序和碳燃烧主序时,我们发现这类天体也被排除在外。通过排除,我们发现只有简并支持的致密天体-WD和中子星-才是SN 2011 fe的主星。除了少量的警告外,我们还将伴星(次级)半径限制为Rc <~ 0.1 R_sun,排除了Roche Lobe溢出红巨星和主序星伴星。

英文摘要:

While a white dwarf is, from a theoretical perspective, the most plausible primary star in Type Ia supernova (SN Ia), many other candidates have not been formally ruled out. Shock energy deposited in the envelope of any exploding primary contributes to the early SN brightness and, since this radiation energy is degraded by expansion after the explosion, the diffusive luminosity depends on the initial primary radius. We present a new non-detection limit of the nearby SN Ia 2011fe, obtained what appears to be just 4 hours after explosion, allowing us to directly constrain the initial primary radius, R_p. Coupled with the non-detection of a quiescent X-ray counterpart and the inferred synthesized Ni mass, we show that R_p <~ 0.02 R_sun (a factor of 5 smaller than previously inferred), that the average density of the primary must be rho_p > 10,000 gm cm^{-3}, and that the effective temperature must be less than a few x 10^5 K. This rules out hydrogen burning main sequence stars and giants. Constructing the helium-burning main sequence and carbon-burning main sequence, we find such objects are also excluded. By process of elimination, we find that only degeneracy-supported compact objects---WDs and neutron stars---are viable as the primary star of SN 2011fe. With few caveats, we also restrict the companion (secondary) star radius to R_ c <~ 0.1 R_sun, excluding Roche-Lobe overflowing red giant and main-sequence companions to high significance.

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