标题： 从星系中分辨率光谱提取恒星形成历史 显示英文标题

标题： Extracting Star Formation Histories from Medium-resolution Galaxy Spectra

摘要： 我们对现有的数据压缩算法MOPED进行了改造，用于从星系的中分辨率光谱中提取中位数似然恒星形成（SF）历史。 通过关注星系光谱中的高频成分，我们最小化了来自光谱-测光校准和尘埃固有消光引起的潜在不确定性。 我们使用具有不同SF历史的模型星系的高频光谱来验证我们的方法，在波长范围为3650-8500 Å、分辨率为约2000的情况下进行测试。 我们表明，该方法可以在不知道金属丰度的情况下，以一种对信噪比敏感的方式恢复这些模型的完整SF历史。 研究每个波长处的流量对不同年龄恒星质量分数的敏感性，使我们能够在星系光谱中识别新的与年龄相关的特征。 我们还强调了在恢复那些中间年龄恒星的光学特征被较年轻和较年老恒星掩盖的星系的SF历史时存在的根本限制。 我们将此方法应用于从SDSS EDR形态学识别的早期和晚期类型星系的最高质量光谱中推导平均SF历史[...]。 我们还调查了在限定星等样本的SDSS-EDR堆叠光谱中的高频信号对宇宙整体SF历史的约束。 我们确认今天最庞大星系中的恒星群体似乎平均比最轻量级的星系中的恒星群体形成得更早。 我们的结果并不支持宇宙在红移低于1时SF活动存在统计显著峰值的最近建议，尽管这种峰值并未被排除[简化]。 显示英文摘要

摘要： We adapt an existing data compression algorithm, MOPED, to the extraction of median-likelihood star formation (SF) histories from medium-resolution galaxy spectra. By focusing on the high-pass components of galaxy spectra, we minimize potential uncertainties arising from the spectro-photometric calibration and intrinsic attenuation by dust. We validate our approach using model high-pass spectra of galaxies with different SF histories covering the wavelength range 3650-8500 A at a resolving power of about 2000. We show that the method can recover the full SF histories of these models, without prior knowledge of the metallicity, to within an accuracy that depends sensitively on signal-to-noise ratio. The investigation of the sensitivity of the flux at each wavelength to the mass fraction of stars of different ages allows us to identify new age-sensitive features in galaxy spectra. We also highlight a fundamental limitation in the recovery of the SF histories of galaxies for which the optical signatures of intermediate-age stars are masked by those of younger and older stars. We apply this method to derive average SF histories from the highest-quality spectra of morphologically identified early- and late-type galaxies in the SDSS EDR [...]. We also investigate the constraints set by the high-pass signal in the stacked spectra of a magnitude-limited sample of SDSS-EDR galaxies on the global SF history of the Universe. We confirm that the stellar populations in the most massive galaxies today appear to have formed on average earlier than those in the least massive ones. Our results do not support the recent suggestion of a statistically significant peak in the SF activity of the Universe at redshifts below unity, although such a peak is not ruled out [abridged].