The reddening law of Type Ia Supernovae: separating intrinsic variability from dust using equivalent widths
The reddening law of Type Ia Supernovae: separating intrinsic variability from dust using equivalent widths
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DOI：
10.1051/0004-6361/201116723
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发表时间：
2011-03
影响因子：
6.5
通讯作者：
N. Chotard;E. Gangler;G. Aldering;P. Antilogus;C. Aragon;S. Bailey;C. Baltay;S. Bongard;C. Buton;A. Canto;Michael Childress;Michael Childress;Y. Copin;H. Fakhouri;H. Fakhouri;E. Hsiao;M. Kerschhaggl;M. Kowalski;S. Loken;P. Nugent;P. Nugent;K. Paech;R. Pain;E. Pecontal;R. Pereira;Saul Perlmutter;Saul Perlmutter;D. Rabinowitz;K. Runge;R. Scalzo;R. Scalzo;G. Smadja;C. Tao;R. Thomas;B. Weaver;C. Wu;C. Wu
中科院分区：
文献类型：
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作者：
N. Chotard;E. Gangler;G. Aldering;P. Antilogus;C. Aragon;S. Bailey;C. Baltay;S. Bongard;C. Buton;A. Canto;Michael Childress;Michael Childress;Y. Copin;H. Fakhouri;H. Fakhouri;E. Hsiao;M. Kerschhaggl;M. Kowalski;S. Loken;P. Nugent;P. Nugent;K. Paech;R. Pain;E. Pecontal;R. Pereira;Saul Perlmutter;Saul Perlmutter;D. Rabinowitz;K. Runge;R. Scalzo;R. Scalzo;G. Smadja;C. Tao;R. Thomas;B. Weaver;C. Wu;C. Wu
我们利用76颗Ia型超新星（SNe Ia），用光学分光光度法研究了近区超新星工厂获得的B波段最大光2.5天内的Si和Ca特征对超新星内禀光度的影响，并确定了一个尘埃红化规律。我们使用Si II λ4131的等效宽度代替光变曲线的拉伸来解释一阶固有光度变化。由此产生的经验光谱红化定律表现出与Ca II和Si II λ6355相关的强烈特征。在应用基于Ca II H&K等效宽度的校正后，我们发现与Cardelli消光定律一致的红化定律。使用相同的输入数据，我们将此结果与合成静止帧类UBVRI光度学进行比较，以模仿文献观测。在对与Si II λ4131和Ca II H&K等效宽度相关的特征进行校正并引入颜色之间的经验相关性之后，我们确定了每个波段中的尘埃成分。我们发现总消光比与选择性消光比的值，R v = 2.8 ± 0.3。这与银河系的值相一致，与大多数以前的分析中发现的低R v值相反。这一结果表明，解释超新星Ia的颜色及其与经典消光定律的兼容性的长期争议，这对它们作为宇宙学探测器的使用至关重要，可以通过处理颜色的色散和超新星Ia光谱中明显特征的可变性来解释。
We employ 76 type Ia supernovae (SNe Ia) with optical spectrophotometry within 2.5 days of B-band maximum light obtained by the Nearby Supernova Factory to derive the impact of Si and Ca features on the supernovae intrinsic luminosity and determine a dust reddening law. We use the equivalent width of Si II λ4131 in place of the light curve stretch to account for first-order intrinsic luminosity variability. The resulting empirical spectral reddening law exhibits strong features that are associated with Ca II and Si II λ6355. After applying a correction based on the Ca II H&K equivalent width we find a reddening law consistent with a Cardelli extinction law. Using the same input data, we compare this result to synthetic rest-frame UBVRI-like photometry to mimic literature observations. After corrections for signatures correlated with Si II λ4131 and Ca II H&K equivalent widths and introducing an empirical correlation between colors, we determine the dust component in each band. We find a value of the total-to-selective extinction ratio, R v = 2.8 ± 0.3. This agrees with the Milky Way value, in contrast to the low R v values found in most previous analyses. This result suggests that the long-standing controversy in interpreting SN Ia colors and their compatibility with a classical extinction law, which is critical to their use as cosmological probes, can be explained by the treatment of the dispersion in colors, and by the variability of features apparent in SN Ia spectra.