标题： 高红移Ia型超新星光谱及其与低红移对应体的比较 显示英文标题

标题： Spectra of High-Redshift Type Ia Supernovae and a Comparison with their Low-Redshift Counterparts

摘要： 我们展示了14颗高红移（0.17 < z < 0.83）超新星的光谱，这些超新星是由超新星宇宙学计划发现的，作为测量宇宙参数活动的一部分。 这些光谱被用来确定红移并分类超新星类型，这是超新星用于宇宙学研究的必要信息。 红移要么从宿主星系的光谱中推导出来，要么从超新星本身的光谱中推导出来。 通过与附近超新星的光谱匹配，我们提供了证据表明这些超新星是Ia型超新星。 我们发现，根据这种拟合过程确定的光谱相对于最大亮度的时间与从测光光变曲线确定的时间一致，并且低红移和高红移的Ia型超新星的光谱时间序列无法区分。 我们还显示，从蓝移CaHK测量的膨胀速度与低红移Ia型超新星的测量值一致。 从这些初步的定量比较中，我们没有发现这些低红移和高红移样本之间Ia型超新星属性有进化迹象。 因此，尽管我们的样本可能不完整，但我们得出结论，在高红移处存在一组Ia型超新星，其光谱特性与低红移处的相同。 显示英文摘要

摘要： We present spectra for 14 high-redshift (0.17 < z < 0.83) supernovae, which were discovered by the Supernova Cosmology Project as part of a campaign to measure cosmological parameters. The spectra are used to determine the redshift and classify the supernova type, essential information if the supernovae are to be used for cosmological studies. Redshifts were derived either from the spectrum of the host galaxy or from the spectrum of the supernova itself. We present evidence that these supernovae are of Type Ia by matching to spectra of nearby supernovae. We find that the dates of the spectra relative to maximum light determined from this fitting process are consistent with the dates determined from the photometric light curves, and moreover the spectral time-sequence for SNe Type Ia at low and high redshift is indistinguishable. We also show that the expansion velocities measured from blueshifted CaHK are consistent with those measured for low-redshift Type Ia supernovae. From these first-level quantitative comparisons we find no evidence for evolution in SNIa properties between these low- and high-redshift samples. Thus even though our samples may not be complete, we conclude that there is a population of SNe Ia at high redshift whose spectral properties match those at low redshift.