Modeling IR Spectral Energy Distributions: A Pilot Study of Starburst Parameters and Silicate Absorption Curves for Some GOALS Galaxies
Michael A. Dopita, Lee Armus, Lisa J. Kewley, Jeff A. Rich, Dave Sanders, Phillip N. Appleton, Ben H. P. Chan, Vassilis Charmandaris, Aaron S. Evans, David T. F… 展开作者
Michael A. Dopita, Lee Armus, Lisa J. Kewley, Jeff A. Rich, Dave Sanders, Phillip N. Appleton, Ben H. P. Chan, Vassilis Charmandaris, Aaron S. Evans, David T. Frayer, Justin H. Howell, Hanae Inami, Joseph A. Mazzarella, Andreea Petric, Sabrina Stierwalt, Jason Surace
备注：
Accepted for publication in Astrophysics & Space Science, 18pp
本文介绍了一个试点研究的光谱能量分布（SED）的拟合和推导的物理参数的19个星系观测的一部分，大天文台全天LIRG巡天（GOALS）的调查所观察到的\emph{Spitzer Space Telescope}。为此，我们使用了Dopita和他的同事在一系列论文中开发的泛谱拟合工具。我们表明，标准的李和德雷恩“天文硅酸盐”模型不能提供一个很好的适合硅酸盐吸收功能中观察到的严重尘埃熄灭（$A_{\rm V} \sim 50$马格。）星爆我们已经得出了一个经验适合在这些对象中的“星爆硅酸盐”的吸收。这种吸收曲线与硅酸盐颗粒在星暴环境中比在本地银河系星际介质中系统性地更大是一致的。我们证明了敏感性的SED拟合每个拟合参数，并得出这些参数的星系没有嵌入AGN。这种方法简单，并提供了合理的强大和统一的参数的星暴，特别是至于恒星形成率，人口的老恒星，紧凑的星暴区域和总前景消光的关注。然而，化学丰度和光学消光不能可靠地确定通过这种分析，和光学SED也将需要提供一个完整的表征的星爆区和周围的星系。
英文摘要：
This paper describes a pilot study into the spectral energy distribution (SED) fitting and the derivation of physical parameters for 19 galaxies observed as part of the Great Observatories All-sky LIRG Survey (GOALS) survey as observed with the \emph{Spitzer Space Telescope}. For this we have used the pan-spectral fitting tools developed in a series of papers by Dopita and his co-workers. We show that the standard Lee and Draine `astronomical silicate' model cannot provide a good fit to the silicate absorption features as observed in the heavily dust-extinguished ($A_{\rm V} \sim 50$mag.) starbursts. We have derived an empirical fit to the `starburst silicate' absorption in these objects. This absorption curve is consistent with the silicate grains being systematically larger in starburst environments than in the local Galactic interstellar medium. We demonstrate the sensitivity of the SED fitting to each of the fitted parameters, and derive these parameters for those galaxies which do not have an embedded AGN. This technique is simple and provides reasonably robust and uniform parameters for the starburst, especially as far as the star formation rate, population of old stars, compactness of the starburst region and total foreground extinction are concerned. However, the chemical abundances and the optical extinction cannot be reliably determined by this analysis, and optical SEDs will also be required to provide a complete characterization of the starburst region and of the surrounding galaxy.
Massive ETGs are thought to form through a two-phase process. At early times, an intense and fast starburst forms blue and disk-dominated galaxies. After quenching, the remaining structures become red, compact and massive, i.e., 'red nuggets'. Then, a time-extended second phase which is dominated by mergers, causes structural evolution and size growth. Given the stochastic nature of mergers, a small fraction of red nuggets survives, without any interaction, massive and compact until today: relic galaxies. Since this fraction depends on the processes dominating the size growth, counting relics …
The star formation history and metal content of the "Green Peas". New detailed GTC-OSIRIS spectrophotometry of three galaxies
我们提出了深宽波段成像和长缝光谱的三个紧凑，低质量的星暴星系在红移z \sim 0.2-0.3，也被称为绿豆（GP）。我们测量电离气体的物理性质，并获得高精度的几个物种的丰度。我们发现，这三个GP显示相对较低的消光，低的氧丰度，和显着高的N/O比，我们还报告在这些星系中的沃尔夫-拉叶星（WR）的检测清晰的签名。我们进行了试点光谱合成研究，使用人口和进化合成模型的组合。他们的输出是在定性协议，强烈建议的形成历史占主导地位的恒星爆发。与WR星的存在一致，这些模型表明，这些GP目前正在经历一次主要的星暴，产生约4%至约20%的恒星质量。然而，正如模型所暗示的那样，它们是古老的星系，在几个Gyr之前形成了大部分恒星质量。通过对其中一个星系的Mg I 5167、5173吸收线的探测，用光谱学方法证实了老星的存在。此外，我们进行了表面测光的基础上HST数据的研究，这表明，这三个星系的低表面亮度包络指数。如果由于恒星的排放，后者是结构上兼容的发光BCD/HII星系的演化主机，这表明GPS是可识别的本地BCD的组装历史中的主要情节。这些结论突出了这些天体作为研究宇宙晚期星系演化实验室的重要性。
