在1<z<3时透镜半导体的中红外光谱：接近MIPS混淆极限的源的性质
Mid-Infrared Spectroscopy of Lensed Galaxies at 1<z<3: The Nature of Sources Near the MIPS Confusion Limit
摘要：
我们目前斯皮策/IRS中红外光谱的15引力透镜，24微米-选定的星系，并结合4个额外的非常微弱的星系与IRS光谱的文献中的结果。该样品的中值固有24微米通量密度为130微焦耳，使非常微弱的24微米源，占主导地位的斯皮策宇宙学调查的数量计数的光谱特性的系统调查。19个星系光谱中有6个（32%）显示出AGN的强中红外连续谱; X射线探测证实了其中3个星系中存在AGN，并揭示了另外两个星系中的AGN。这些结果表明，核吸积可能会贡献更多的流量微弱的24微米-选定的样品比以前假设的。几乎所有的光谱显示一些芳香族（PAH）的排放功能，测量的芳香族通量比不显示从z=0的演变。特别是，SMM J163554.2+661225的高S/N中红外光谱与低红移，低光度模板非常吻合。我们比较了恒星形成星系的静止坐标系8微米和总红外光度，发现这个比率与总红外光度的行为从z=2到z=0有适度的演变。由于高芳族-连续通量比在这些星系中排除了活动星系核的主要贡献，这一发现意味着系统的演化与红移的红外源的结构和/或金属丰度。它也对从24微米测量推断的恒星形成率的估计有影响，在这个意义上，在z ~2，一个给定的观测框架24微米光度对应于一个较低的热光度比将推断从低红移模板在相应的静止波长类似的光度。
英文摘要：
We present Spitzer/IRS mid-infrared spectra for 15 gravitationally lensed, 24 micron--selected galaxies, and combine the results with 4 additional very faint galaxies with IRS spectra in the literature. The median intrinsic 24 micron flux density of the sample is 130 microJy, enabling a systematic survey of the spectral properties of the very faint 24 micron sources that dominate the number counts of Spitzer cosmological surveys. Six of the 19 galaxy spectra (32%) show the strong mid-IR continuua expected of AGN; X-ray detections confirm the presence of AGN in three of these cases, and reveal AGNs in two other galaxies. These results suggest that nuclear accretion may contribute more flux to faint 24 micron--selected samples than previously assumed. Almost all the spectra show some aromatic (PAH) emission features; the measured aromatic flux ratios do not show evolution from z=0. In particular, the high S/N mid-IR spectrum of SMM J163554.2+661225 agrees remarkably well with low--redshift, lower--luminosity templates. We compare the rest-frame 8 micron and total infrared luminosities of star--forming galaxies, and find that the behavior of this ratio with total IR luminosity has evolved modestly from z=2 to z=0. Since the high aromatic--to--continuum flux ratios in these galaxies rule out a dominant contribution by AGN, this finding implies systematic evolution in the structure and/or metallicity of infrared sources with redshift. It also has implications for the estimates of star forming rates inferred from 24 micron measurements, in the sense that at z ~2, a given observed frame 24 micron luminosity corresponds to a lower bolometric luminosity than would be inferred from low-redshift templates of similar luminosity at the corresponding rest wavelength.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
