The effect of stellar evolution uncertainties on the rest-frame ultraviolet stellar lines of C iv and He ii in high-redshift Lyman-break galaxies
The effect of stellar evolution uncertainties on the rest-frame ultraviolet stellar lines of C iv and He ii in high-redshift Lyman-break galaxies
复制标题
DOI：
10.1111/j.1365-2966.2011.19713.x
复制
发表时间：
2011-09
影响因子：
4.8
通讯作者：
J. Eldridge;E. Stanway
中科院分区：
文献类型：
--
作者：
J. Eldridge;E. Stanway
年轻的大质量恒星主导着恒星形成星系的静止坐标系紫外光谱。在高红移（z > 2）时，这些静止坐标系的紫外特征被移到光学坐标系中，引力透镜、深光谱学和光谱叠加分析的结合使得这些源的恒星种群特征得以研究。我们使用我们的恒星人口合成代码二进制人口和光谱合成（bpass），以适应两个强大的休息帧紫外光谱特征在公布的莱曼break星系光谱，考虑到二进制演化对恒星光谱的影响。特别地，我们考虑了准均匀演化（由快速旋转恒星的旋转混合引起），金属丰度和碳和氧的相对丰度对He iiλ1640 A和C ivλ1548，1551 A谱线观测强度的影响。我们发现，莱曼break星系在z = 2-3的光谱最适合中等亚太阳的金属丰度，并与耗尽的碳氧比。我们还发现，最低的金属丰度源的光谱是最好的拟合模型光谱中的He II发射线是由包括大质量的恒星被旋转起来的效果，使这些快速旋转的恒星经历准均匀的演变过程中的质量转移。
Young, massive stars dominate the rest-frame ultraviolet (UV) spectra of star-forming galaxies. At high redshifts (z > 2), these rest-frame UV features are shifted into the observed-frame optical and a combination of gravitational lensing, deep spectroscopy and spectral stacking analysis allows the stellar population characteristics of these sources to be investigated. We use our stellar population synthesis code Binary Population and Spectral Synthesis (bpass) to fit two strong rest-frame UV spectral features in published Lyman-break galaxy spectra, taking into account the effects of binary evolution on the stellar spectrum. In particular, we consider the effects of quasi-homogeneous evolution (arising from the rotational mixing of rapidly rotating stars), metallicity and the relative abundance of carbon and oxygen on the observed strengths of He iiλ1640 A and C ivλ1548, 1551 A spectral lines. We find that Lyman-break galaxy spectra at z∼ 2–3 are best fitted with moderately sub-solar metallicities, and with a depleted carbon-to-oxygen ratio. We also find that the spectra of the lowest metallicity sources are best fitted with model spectra in which the He ii emission line is boosted by the inclusion of the effect of massive stars being spun-up during binary mass transfer so these rapidly rotating stars experience quasi-homogeneous evolution.