arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0705.0726astro-ph
收藏

衰减率校正的Ia型超新星上升时间的多样性:一种模式还是两种?

Diversity of Decline-Rate-Corrected Type Ia Supernova Rise Times: One Mode or Two?

Mark Strovink

摘要:

B波段光变曲线的上升时间为8个异常良好观察附近的Ia型超新星(SNe)是由一个新开发的模板构建算法,使用光变曲线函数,是平滑的,灵活的,并从外部导出的模板和其他先验假设的潜在偏差。从现有的文献,光度BVRI数据收集了许多个月,包括最早的点,调和,合并,并适合于一个独特的时间爆炸的每个SN。平均而言,在对光变曲线下降率进行校正后,三个SNe在18.81 ± 0.36天内上升,而五个SNe在16.64 ± 0.21天内上升。如果所有8个SNe都是从单亲群体中取样的(统计检验不支持这一假设),则下降率校正的SN上升时间的均方根固有离散度为0.96 + 0.52 - 0.25天--这是该离散度的第一次测量。相应的全球平均上升时间为17.44 +- 0.39天,其中不确定性主要由内在方差决定。该值比两个已发表的平均值短约2天,这两个平均值名义上是精确度的两倍,尽管也是基于小样本。当比较高Z和低Z SN光度来确定宇宙学参数时,使用具有不切实际的上升时间的光变曲线模板会引入偏差。如果光变曲线的采样周期以当前搜索和测量策略的典型方式依赖于z,那么模板上升时间的两天差异可以使光度比较偏差约0.03个星等。

英文摘要:

B-band light-curve rise times for eight unusually well-observed nearby Type Ia supernovae (SNe) are fitted by a newly developed template-building algorithm, using light-curve functions that are smooth, flexible, and free of potential bias from externally derived templates and other prior assumptions. From the available literature, photometric BVRI data collected over many months, including the earliest points, are reconciled, combined, and fitted to a unique time of explosion for each SN. On average, after they are corrected for light-curve decline rate, three SNe rise in 18.81 +- 0.36 days, while five SNe rise in 16.64 +- 0.21 days. If all eight SNe are sampled from a single parent population (a hypothesis not favored by statistical tests), the rms intrinsic scatter of the decline-rate-corrected SN rise time is 0.96 +0.52 -0.25 days -- a first measurement of this dispersion. The corresponding global mean rise time is 17.44 +- 0.39 days, where the uncertainty is dominated by intrinsic variance. This value is ~2 days shorter than two published averages that nominally are twice as precise, though also based on small samples. When comparing high-z to low-z SN luminosities for determining cosmological parameters, bias can be introduced by use of a light-curve template with an unrealistic rise time. If the period over which light curves are sampled depends on z in a manner typical of current search and measurement strategies, a two-day discrepancy in template rise time can bias the luminosity comparison by ~0.03 magnitudes.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑