标题： 红移 z = 0.437 的强 Lyman-alpha 吸收星系的发射线光谱学 显示英文标题

标题： Emission Line Spectroscopy of a Damped Lyman-alpha Absorbing Galaxy at z = 0.437

摘要： 我们展示了凯克望远镜/低分辨成像光谱仪（LRIS）对类星体（QSO）3C196方向上一个候选强引力透镜吸积盘（DLA）星系的光谱观测结果（z_em = 0.871）。 DLA吸收系统红移为z_DLA = 0.437，在使用WFPC2/HST高分辨率成像时，发现了一颗距离类星体1.5"的星系。 我们在吸收红移处检测到了[O II] 3727Å、Hβ、[O III] 5007Å、Hα和[N II] 6584Å的发射线。 根据发射线，我们确定了星系的红移为z_em = 0.4376 ± 0.0006。 这些发射线还使我们能够利用基于不同发射线强度的已建立指数来计算消光修正后的光度和金属丰度指示器。 这些指标表明DLA星系的星际介质（ISM）具有较高的金属丰度，相当于或可能是太阳的两倍（例如，12+log (O/H) = 8.98 ± 0.07）。 根据Hα强度以及由Hα和Hβ相对强度推导出的消光值，恒星形成率约为4.7 ± 0.8 M_solar/yr。 这将该星系归类为富气螺旋星系范围内的星系。 显示英文摘要

摘要： We present Keck/LRIS spectra of a candidate damped Lyman-alpha (DLA) galaxy toward the QSO 3C196 (z_em = 0.871). The DLA absorption system has a redshift of z_DLA = 0.437, and a galaxy at 1.5" from the QSO has been identified in high resolution imaging with WFPC2/HST. We have detected emission lines of [O II] 3727A, Hbeta, [O III] 5007A, Halpha and [N II] 6584A at the absorption redshift. Based on the emission lines, we have found the redshift of the galaxy to be z_em = 0.4376 +/- 0.0006. The emission lines also enabled us to calculate the extinction-corrected luminosities and metallicity indicators using established indices based on line strengths of different emission lines. These indicators suggest that the ISM of the DLA galaxy has a high metallicity comparable to or perhaps twice as much as solar (e.g. 12+log (O/H) = 8.98 +/- 0.07). Based on the strengths of Halpha and on the reddening derived from the relative strengths of Halpha and Hbeta, the star formation rate is 4.7 +/- 0.8 M_solar/yr. This places the galaxy in the range of gas-rich spiral galaxies.