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arXiv 1002.3056astro-ph.COastro-ph.SR
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Lick Observatory Supernova Search附近的超新星比率。IV。延迟时间分布的一种恢复方法

Nearby Supernova Rates from the Lick Observatory Supernova Search. IV. A Recovery Method for the Delay Time Distribution

Dan Maoz, Filippo Mannucci, Weidong Li, Alexei V. Filippenko, Massimo Della Valle, Nino Panagia

摘要:

超新星(SN)延迟时间分布(DTD)-超新星速率与时间的关系,这将伴随着恒星形成的短暂爆发-可以揭示SN祖先和化学富集时间尺度。以前试图恢复DTD的方法是比较平均SN速率与宇宙恒星形成历史(SFH)的红移,或者比较不同平均年龄星系之间的SN速率。我们提出了一种方法来恢复SN DTD,避免这种平均。我们将单个星系的SFH与每个星系中发现的SNe数量进行比较(通常为零,有时为一个或几个SNe)。我们应用该方法的子样本的3505个星系,托管82 SNe Ia和119核心坍缩SNe(CC SNe),从利克天文台SN搜索(LOSS),与SFHS重建SDSS光谱。我们发现在我们最短的延迟,“提示”,在<4.2亿年的bin中有一个> 2西格玛的SN Ia DTD信号。尽管存在系统误差,但由于SDSS光谱光纤的有限孔径,这导致一些瞬发信号泄漏到后面的DTD箱,数据需要在>99%置信度下的瞬发SNe Ia。我们进一步发现,在4西格玛,SNe Ia的“延迟”> 2.4 Gyr。因此,数据支持存在即时和延迟的Ia超新星。在CC SN DTD上的时间积分是0.010+/-0.002 SNe/Msun,正如预期的那样,如果所有质量>8 Msun的恒星都会导致可见的SN爆炸。这反对CC SNe的最小质量>10兆太阳,也反对很大一部分大质量恒星在没有爆炸的情况下坍缩。对于Ia型超新星,时间积分的DTD为0.0023+/-0.0006 SNe/Msun,其中大部分的延迟小于2.4 Gyr。我们表明,使用模拟,该方法的应用程序的全部现有的损失样本,但完整和无偏的SFH估计的调查星系,可以提供一个详细的测量的SN Ia DTD。

英文摘要:

The supernova (SN) delay-time distribution (DTD) - the SN rate versus time that would follow a brief burst of star formation - can shed light on SN progenitors, and on chemical enrichment timescales. Previous attempts to recover the DTD have used comparisons of mean SN rates vs. redshift to cosmic star-formation history (SFH), or comparison of SN rates among galaxies of different mean ages. We present an approach to recover the SN DTD that avoids such averaging. We compare the SFHs of individual galaxies to the numbers of SNe discovered in each galaxy (generally zero, sometimes one or a few SNe). We apply the method to a subsample of 3505 galaxies, hosting 82 SNe Ia and 119 core-collapse SNe (CC SNe), from the Lick Observatory SN Search (LOSS), with SFHs reconstructed from SDSS spectra. We find a >2sigma SN Ia DTD signal in our shortest-delay, "prompt", bin at <420 Myr. Despite a systematic error, due to the limited aperture of the SDSS spectroscopic fibres, which causes some of the prompt signal to leak to the later DTD bins, the data require prompt SNe Ia at the >99% confidence. We further find, at 4sigma, SNe Ia that are "delayed" by > 2.4 Gyr. Thus, the data support the existence of both prompt and delayed SNe Ia. The time integral over the CC SN DTD is 0.010+/-0.002 SNe per Msun, as expected if all stars of mass >8 Msun lead to visible SN explosions. This argues against a minimum mass for CC SNe of >10 Msun, and against a significant fraction of massive stars that collapse without exploding. For SNe Ia, the time-integrated DTD is 0.0023+/-0.0006 SNe per Msun formed, most of them with delays < 2.4 Gyr. We show, using simulations, that application of the method to the full existing LOSS sample, but with complete and unbiased SFH estimates for the survey galaxies, could provide a detailed measurement of the SN Ia DTD.

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