标题： 6L* z=5.5 星暴星系的紫外连续光谱 spectroscopy 显示英文标题

标题： UV Continuum Spectroscopy of a 6L* z=5.5 Starburst Galaxy

摘要： 我们获得了来自超亮（z_850 = 24.3）的红移 z = 5.515 ± 0.003 的恒星形成星系（BD38）的一条高信噪比（22.3 小时积分时间）的 UV 连续谱 VLT FORS2 光谱，该星系位于红移 z = 1.24 的 RDCS 1252.9-2927 星团所在的区域。 此天体显示出显著的连续谱（0.41 ± 0.02 \muJy 在 \lambda 1300 Å）和低电离的星际吸收特征，与较低红移（z ~ 3）的 LBG 典型特征相似；这是通过金属吸收谱线特征确认的最高红移 LBG。 吸收特征的等效宽度与 z ~ 3 强 Lyman alpha\alpha 吸收体相当。 未检测到明显的 Lyman alpha\alpha 发射线（F <= 1.4 * 10^-18 ergs cm^-2 s^-1, 3\sigma 倍标准差）。 此天体的半光半径为 1.6 kpc (0\farcs 25)，由框架内 UV 辐射推导出的恒星形成率为 SFR_UV = 38 h^-2_0.7 M_sun yr^-1 （修正尘埃消光后为 142 h^-2_0.7 M_sun yr^-1）。 根据最近关于 z ~ 6 UV 光度函数的确定结果，此天体似乎为 6L*。 该天体在 3.6\mu 和 4.5\mu 波段的斯皮策红外阵列相机（IRAC）流量分别为 23.3 和 23.2 AB 星等（已修正聚类透镜效应的 0.3 星等），这意味着根据星族合成模型其质量为 1-6 × 10^10 太阳质量。在 z_850 带中，这个星系比迄今为止所有确认的约 z = 6 的 i 滴漏源都要亮，并且在 3.6\mu 和 4.5\mu 波段也更亮，是目前已知 z > 5 的最亮正在发生恒星爆发的星系。——摘录自摘要 显示英文摘要

摘要： We have obtained a high S/N (22.3 hr integration) UV continuum VLT FORS2 spectrum of an extremely bright (z_850 = 24.3) z = 5.515 +/- 0.003 starforming galaxy (BD38) in the field of the z = 1.24 cluster RDCS 1252.9-2927. This object shows substantial continuum (0.41 +/- 0.02 \muJy at \lambda1300) and low-ionization interstellar absorption features typical of LBGs at lower redshift (z ~ 3); this is the highest redshift LBG confirmed via metal absorption spectral features. The equivalent widths of the absorption features are similar to z ~ 3 strong Ly\alpha absorbers. No noticeable Ly\alpha emission was detected (F <= 1.4 * 10^-18 ergs cm^-2 s^-1, 3\sigma). The half-light radius of this object is 1.6 kpc (0\farcs25) and the star formation rate derived from the rest-frame UV luminosity is SFR_UV = 38 h^-2_0.7 M_sun yr^-1 (142 h^-2_0.7 M_sun yr^-1 corrected for dust extinction). In terms of recent determinations of the z ~ 6 UV luminosity function, this object appears to be 6L*. The Spitzer IRAC fluxes for this object are 23.3 and 23.2 AB mag (corrected for 0.3 mag of cluster lensing) in the 3.6\mu and 4.5\mu channels, respectively, implying a mass of 1-6 * 10^10 M_sun from population synthesis models. This galaxy is brighter than any confirmed z ~ 6 i-dropout to date in the z_850 band, and both the 3.6\mu and 4.5\mu channels, and is the most massive starbursting galaxy known at z > 5. -- Abstract Abridged