The ESO’s VLT type Ia supernova spectral set of the final two years of SNLS-猫眼课题宝

DOI：

10.1051/0004-6361/201731924

发表时间：

2017-12

期刊：

Astronomy & Astrophysics

影响因子：

6.5

通讯作者：

中科院分区：

物理与天体物理2区

文献类型：

作者：

C. Balland;F. Cellier-Holzem;C. Lidman;P. Astier;M. Betoule;R. Carlberg;A. Conley;R. Ellis;R. Ellis;J. Guy;D. Hardin;I. Hook;I. Hook;D. Howell;D. Howell;R. Pain;C. Pritchet;N. Regnault;M. Sullivan;V. Arsenijević;S. Baumont;P. El-Hage;S. Fabbro;D. Fouchez;A. Mitra;A. Moller;A. Mourão;J. Neveu;M. Roman;V. Ruhlmann-Kleider

目标。我们的目标是展示 68 颗新的高红移 Ia 型超新星 (SNe Ia) 的 70 个光谱，这些光谱是在超新星遗产巡天 (SNLS) 运行的最后两年（2006-2008 年）期间在 ESO 的 VLT 上测量的。这个新样本补充了 VLT 三年光谱集。总之，这两个数据集构成了在 VLT 上测量的 SNLS SN Ia 光谱的五年样本，最终的 SNLS 宇宙学分析将部分基于该样本。在考虑的红移范围内，该样品在均匀性和光谱数量方面是独一无二的。我们用它来研究超新星 Ia 群的红移光谱演化的可能性以及超新星 Ia 光谱特性作为光曲线拟合参数和宿主星系质量的函数。方法。还原和提取基于 IRAF 标准任务和我们自己的还原管道。红移是尽可能根据主星系线或超新星特征来估计的。我们使用分光光度 SN Ia 模型 SALT2 结合一组模拟宿主星系污染的星系模板来评估候选者的 Ia 型性质。结果。我们确定了 68 个新的超新星 Ia，其红移范围为 z = 0.207 到 z = 0.98，平均红移为 z = 0.62。每个光谱及其最适合的 SALT2 模型均单独呈现。将这个新样本添加到 SNLS 的三年 VLT 样本中，最终数据集包含与 VLT 识别的 192 个 SNe Ia 相对应的 209 个光谱。我们还发布了其他候选星系（宿主星系或其他瞬变星系）的红移，其光谱是与活超新星 Ia 的光谱同时获得的。该列表提供了一个新的红移目录，可用于即将进行的星系巡天。使用完整的 VLT SNe Ia 样本，我们围绕最大光构建了复合光谱，其中包括颜色、光曲线形状参数（“拉伸”）、宿主星系质量和红移。我们发现高 z 值超新星 Ia 比低 z 值对应物更蓝、更亮，并且具有更弱的中间质量元素吸收线，其水平与选择效应的预期一致。我们还发现超新星 Ia 在低质量主星系 (M < 1010M⊙) 或局部蓝色 U-V 颜色中存在 [3000–3400] Å 范围内的通量过剩，并建议在未来的宇宙学研究中，除了拉伸和颜色之外，可以将 UV 通量（或局部颜色）用作第三个标准化参数。

Aims. We aim to present 70 spectra of 68 new high-redshift type Ia supernovae (SNe Ia) measured at ESO’s VLT during the final two years of operation (2006–2008) of the Supernova Legacy Survey (SNLS). This new sample complements the VLT three year spectral set. Altogether, these two data sets form the five year sample of SNLS SN Ia spectra measured at the VLT on which the final SNLS cosmological analysis will partly be based. In the redshift range considered, this sample is unique in terms of homogeneity and number of spectra. We use it to investigate the possibility of a spectral evolution of SNe Ia populations with redshift as well as SNe Ia spectral properties as a function of lightcurve fit parameters and the mass of the host-galaxy. Methods. Reduction and extraction are based on both IRAF standard tasks and our own reduction pipeline. Redshifts are estimated from host-galaxy lines whenever possible or alternatively from supernova features. We used the spectro-photometric SN Ia model SALT2 combined with a set of galaxy templates that model the host-galaxy contamination to assess the type Ia nature of the candidates. Results. We identify 68 new SNe Ia with redshift ranging from z = 0.207 to z = 0.98 for an average redshift of z = 0.62. Each spectrum is presented individually along with its best-fit SALT2 model. Adding this new sample to the three year VLT sample of SNLS, the final dataset contains 209 spectra corresponding to 192 SNe Ia identified at the VLT. We also publish the redshifts of other candidates (host galaxies or other transients) whose spectra were obtained at the same time as the spectra of live SNe Ia. This list provides a new redshift catalog useful for upcoming galaxy surveys. Using the full VLT SNe Ia sample, we build composite spectra around maximum light with cuts in color, the lightcurve shape parameter (“stretch”), host-galaxy mass and redshift. We find that high-z SNe Ia are bluer, brighter and have weaker intermediate mass element absorption lines than their low-z counterparts at a level consistent with what is expected from selection effects. We also find a flux excess in the range [3000–3400] Å for SNe Ia in low mass host-galaxies (M < 1010M⊙) or with locally blue U–V colors, and suggest that the UV flux (or local color) may be used in future cosmological studies as a third standardization parameter in addition to stretch and color.

The ESO’s VLT type Ia supernova spectral set of the final two years of SNLS

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