Strong dependence of Type Ia supernova standardization on the local specific star formation rate-猫眼课题宝

DOI：

10.1051/0004-6361/201730404

发表时间：

2018-06

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：

M. Rigault;V. Brinnel;G. Aldering;P. Antilogus;C. Aragon;S. Bailey;C. Baltay;K. Barbary;S. Bongard;Kyle Boone;C. Buton;M. Childress;N. Chotard;Y. Copin;S. Dixon;P. Fagrelius;U. Feindt;D. Fouchez;E. Gangler;B. Hayden;W. Hillebrandt;D. Howell;A. Kim;M. Kowalski;D. Kuesters;P. Léget;S. Lombardo;Q. Lin;J. Nordin;R. Pain;E. Pecontal;R. Pereira;S. Perlmutter;D. Rabinowitz;K. Runge;D. Rubin;C. Saunders;G. Smadja;C. Sofiatti;N. Suzuki;S. Taubenberger;C. Tao;R. Thomas

作为一个持续的努力，以识别，理解和纠正天体物理学偏见的标准化Ia型超新星（SN Ia）的宇宙学的一部分，我们已经统计分类的大样本附近的SNe Ia到那些主要位于年轻或老年人的环境。这种分类是基于在距离每个SN位置1千秒差距（LsSFR）的投影距离内测量的特定星星形成率。与直接使用本地星星形成率相比，这是一个重要的改进，因为它提供了可用SN祖先的相对数量的标准化，并且对尘埃的灭绝更鲁棒。我们发现，经过传统的光变曲线标准化后，主要是较年轻环境中的超新星Ia比主要是较老环境中的超新星Ia暗ΔY = 0.163 ± 0.029 mag（5.7σ）。这是迄今为止测量到的与主星系环境相关的最强标准化SN Ia亮度系统。对于同一组Ia型超新星来说，总恒星质量较低或较高的主恒星之间的标准化亮度步长较小，ΔM = 0.119 ± 0.032等（4.5σ）。当同时拟合时，环境-年龄偏差仍然非常显著，ΔY = 0.129 ± 0.032 mag（4.0σ），而全球恒星质量阶跃减小到ΔM = 0.064 ± 0.029 mag（2.2σ）。因此，大约70%的差异从恒星质量的步骤是由于一个潜在的依赖环境为基础的祖年龄。此外，我们验证，单独使用本地星星形成率是不是强大的LsSFR在排序SNe Ia到更亮和更暗的子集。标准化，只使用超新星Ia在年轻的环境中减少了总色散从0.142 ± 0.008马格到0.120 ± 0.010马格。我们表明，随着环境年龄的发展与红移，一个很强的偏见，特别是对暗能量状态方程的导数的测量，可以开发。幸运的是，使用我们当地特定的星星形成率指标来测量和校正这种效应的数据很可能用于许多下一代超新星宇宙学实验。

As part of an on-going effort to identify, understand and correct for astrophysics biases in the standardization of Type Ia supernovae (SN Ia) for cosmology, we have statistically classified a large sample of nearby SNe Ia into those that are located in predominantly younger or older environments. This classification is based on the specific star formation rate measured within a projected distance of 1 kpc from each SN location (LsSFR). This is an important refinement compared to using the local star formation rate directly, as it provides a normalization for relative numbers of available SN progenitors and is more robust against extinction by dust. We find that the SNe Ia in predominantly younger environments are ΔY = 0.163 ± 0.029 mag (5.7σ) fainter than those in predominantly older environments after conventional light-curve standardization. This is the strongest standardized SN Ia brightness systematic connected to the host-galaxy environment measured to date. The well-established step in standardized brightnesses between SNe Ia in hosts with lower or higher total stellar masses is smaller, at ΔM = 0.119 ± 0.032 mag (4.5σ), for the same set of SNe Ia. When fit simultaneously, the environment-age offset remains very significant, with ΔY = 0.129 ± 0.032 mag (4.0σ), while the global stellar mass step is reduced to ΔM = 0.064 ± 0.029 mag (2.2σ). Thus, approximately 70% of the variance from the stellar mass step is due to an underlying dependence on environment-based progenitor age. Also, we verify that using the local star formation rate alone is not as powerful as LsSFR at sorting SNe Ia into brighter and fainter subsets. Standardization that only uses the SNe Ia in younger environments reduces the total dispersion from 0.142 ± 0.008 mag to 0.120 ± 0.010 mag. We show that as environment-ages evolve with redshift, a strong bias, especially on the measurement of the derivative of the dark energy equation of state, can develop. Fortunately, data that measure and correct for this effect using our local specific star formation rate indicator, are likely to be available for many next-generation SN Ia cosmology experiments.

Strong dependence of Type Ia supernova standardization on the local specific star formation rate

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