Standardizing Type Ia supernovae optical brightness using near-infrared rebrightening time
Standardizing Type Ia supernovae optical brightness using near-infrared rebrightening time
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DOI：
10.1093/mnras/stw2278
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发表时间：
2016-05
影响因子：
4.8
通讯作者：
H. Shariff;S. Dhawan;X. Jiao;B. Leibundgut;R. Trotta;D. V. Dyk
中科院分区：
文献类型：
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作者：
H. Shariff;S. Dhawan;X. Jiao;B. Leibundgut;R. Trotta;D. V. Dyk
Ia型超新星（SNIa）的精确标准化有助于SNIa作为距离指标的使用。我们分析了22个低z SNIa的均匀样品，由卡内基超新星计划（CSP）在光学和近红外（NIR）观察。我们研究了由于再增亮而导致的NIR波段中的第二个峰的时间t2，作为SNIa峰亮度的替代标准化参数。我们使用BAHAMAS，SNIa宇宙学的贝叶斯分层模型，以确定哈勃图中的剩余散射。我们发现，在没有颜色校正的情况下，与拉伸相比，t2是一个更好的标准化参数：t2的哈勃残差散射的后验间隔为[0.250，0.257]，而单独使用拉伸（x1）时为[0.280，0.287]。我们表明，当采用与颜色校正，T2和拉伸导致类似的残余散射。联合使用颜色、拉伸和t2作为标准化参数不会导致散射的任何进一步减少，这表明t2携带关于拉伸和颜色的冗余信息。随着未来更大的SNIa近红外样品在更高的红移，t2可能是一个有用的数量来执行标准化程序的鲁棒性检查。
Accurate standardisation of Type Ia supernovae (SNIa) is instrumental to the usage of SNIa as distance indicators. We analyse a homogeneous sample of 22 low-z SNIa, observed by the Carnegie Supernova Project (CSP) in the optical and near infra-red (NIR). We study the time of the second peak in the NIR band due to re-brightening, t2, as an alternative standardisation parameter of SNIa peak brightness. We use BAHAMAS, a Bayesian hierarchical model for SNIa cosmology, to determine the residual scatter in the Hubble diagram. We find that in the absence of a colour correction, t2 is a better standardisation parameter compared to stretch: t2 has a 1 sigma posterior interval for the Hubble residual scatter of [0.250, 0.257] , compared to [0.280, 0.287] when stretch (x1) alone is used. We demonstrate that when employed together with a colour correction, t2 and stretch lead to similar residual scatter. Using colour, stretch and t2 jointly as standardisation parameters does not result in any further reduction in scatter, suggesting that t2 carries redundant information with respect to stretch and colour. With a much larger SNIa NIR sample at higher redshift in the future, t2 could be a useful quantity to perform robustness checks of the standardisation procedure.