THE RELATION BETWEEN EJECTA VELOCITY, INTRINSIC COLOR, AND HOST-GALAXY MASS FOR HIGH-REDSHIFT TYPE Ia SUPERNOVAE
THE RELATION BETWEEN EJECTA VELOCITY, INTRINSIC COLOR, AND HOST-GALAXY MASS FOR HIGH-REDSHIFT TYPE Ia SUPERNOVAE
复制标题
DOI：
10.1088/0004-637x/748/2/127
复制
发表时间：
2012-01
期刊：
影响因子：
--
通讯作者：
R. Foley
中科院分区：
文献类型：
--
作者：
R. Foley
最近，利用Ia型超新星（SNe Ia）的大量低红移样本，我们发现了Ia型超新星的喷射速度与本征颜色之间的关系，这提高了Ia型超新星的距离精度，并减少了与尘埃变红相关的潜在系统偏差。迄今为止，还没有任何SN Ia宇宙学结果对“速度-颜色”关系做出修正。为了验证这种关系的存在，并限制其在高红移时的性质，我们研究了由斯隆数字巡天- ii超新星巡天和超新星遗产巡天发现和观测的75个Ia型超新星样本。从每个光谱中，我们分别测量了Ca H&K和Si i λ6355特征，v0Ca H&K和v0Si ii的最大亮度下的喷射速度。利用SN光曲线参数，我们确定了每个SN的本征Bmax−Vmax。与低红移时的发现相似，我们发现具有较高喷射速度的Ia型超新星本质上比具有较低喷射速度的Ia型超新星更红。超新星Ia在低红移和高红移时的喷射速度分布是相似的，这表明目前的宇宙学结果在速度-颜色关系方面应该没有什么偏差。此外，我们发现Ia超新星的喷射速度与宿主星系质量之间有轻微的（2.4σ显著性）趋势，如v0Ca H&K探测到的高质量宿主星系中的Ia超新星往往具有较低的喷射速度。这些结果强调了光谱学对超新星宇宙学的重要性。
Recently, using a large low-redshift sample of Type Ia supernovae (SNe Ia), we discovered a relation between SN Ia ejecta velocity and intrinsic color that improves the distance precision of SNe Ia and reduces potential systematic biases related to dust reddening. No SN Ia cosmological results have yet made a correction for the “velocity–color” relation. To test the existence of such a relation and constrain its properties at high redshift, we examine a sample of 75 SNe Ia discovered and observed by the Sloan Digital Sky Survey-II Supernova Survey and Supernova Legacy Survey. From each spectrum, we measure ejecta velocities at maximum brightness for the Ca H&K and Si ii λ6355 features, v0Ca H&K and v0Si ii, respectively. Using SN light curve parameters, we determine the intrinsic Bmax − Vmax for each SN. Similar to what was found at low redshift, we find that SNe Ia with higher ejecta velocity tend to be intrinsically redder than SNe Ia with lower ejecta velocity. The distributions of ejecta velocities for SNe Ia at low and high redshift are similar, indicating that current cosmological results should have little bias related to the velocity–color relation. Additionally, we find a slight (2.4σ significant) trend between SN Ia ejecta velocity and host-galaxy mass such that SNe Ia in high-mass host galaxies tend to have lower ejecta velocities as probed by v0Ca H&K. These results emphasize the importance of spectroscopy for SN Ia cosmology.