A Redshift Survey of the Submillimeter Galaxy Population
A Redshift Survey of the Submillimeter Galaxy Population
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DOI：
10.1086/428082
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发表时间：
2004-12
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影响因子：
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通讯作者：
S. Chapman;A. Blain;I. Smail;R. Ivison
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作者：
S. Chapman;A. Blain;I. Smail;R. Ivison
我们使用Keck I望远镜获得了73个亚毫米星系（smg）样本的光谱红移，它们的中位通量密度为850 μm，为5.7 mJy，通过它们微弱的射电发射可以获得精确的位置。这些星系的红移范围为z = 3.6，中位红移为2.2，四分位数范围为z = 1.7-2.8。基于我们无线电识别样本的预期选择函数，对纯亚毫米通量有限的样本进行建模，表明中位红移为2.3，其红移分布与光学和无线电选择的类星体非常相似。观测到的红移分布与活动星系核（AGN）和星爆亚样本相似。样本的RAB中位数为24.6。然而，星系的尘埃校正紫外线（UV）光度很少暗示其射电/亚毫米发射所显示的巨大热光度，其结果是，对于具有纯星暴光谱的smg，真实光度可能被低估了约120的中值因子。因此，无线电和亚毫米观测对于选择最明亮的高红移星系至关重要。850 μm、射电和红移数据用于估计尘埃温度和表征光度红移。通过450 μm的测量，我们证实了尘埃温度中值Td = 36±7 K是合理的，该温度是基于局部远红外(FIR)-无线电相关性适用于高红移的假设得出的。单个450 μm的探测结果符合z ~ 2的局部无线电- fir关系。这个中值Td低于局部相似亮度的IRAS 60 μm星系的估计值。我们证明了灰尘温度的变化使得使用简单的长波长光度法估计单个SGMs的红移不可能优于Δz≃1。我们计算了总红外和热光度（从无线电估计的中位数红外光度为8.5 × 1012 L☉），构建了光度函数，并量化了相对于本地IRAS星系z = 0.5-3.5的亚毫米星系群的强烈演化。我们利用热光度和紫外光谱分类确定了星系群AGN含量的下限，并首次直接测量了高度模糊的发光星系对宇宙光度密度历史的贡献变化。我们得出结论，明亮的亚毫米星系与z = 2-3的莱曼断裂星系的恒星形成密度相当，包括低于我们的亚毫米通量极限的星系，这个星系群可能是这个时期大质量恒星形成的主要场所。smg和QSO群体的快速演化与在静止帧紫外中选择的较低光度星系样本所见的形成形成对比，表明smg与宿主QSO的星系晕的形成和演化之间存在密切联系。
We have obtained spectroscopic redshifts using the Keck I telescope for a sample of 73 submillimeter galaxies (SMGs), with a median 850 μm flux density of 5.7 mJy, for which precise positions are available through their faint radio emission. The galaxies lie at redshifts out to z = 3.6, with a median redshift of 2.2 and an interquartile range z = 1.7-2.8. Modeling a purely submillimeter flux-limited sample, based on the expected selection function for our radio-identified sample, suggests a median redshift of 2.3, with a redshift distribution remarkably similar to the optically and radio-selected quasars. The observed redshift distributions are similar for the active galactic nucleus (AGN) and starburst subsamples. The median RAB is 24.6 for the sample. However, the dust-corrected ultraviolet (UV) luminosities of the galaxies rarely hint at the huge bolometric luminosities indicated by their radio/submillimeter emission, with the effect that the true luminosity can be underestimated by a median factor of ~120 for SMGs with pure starburst spectra. Radio and submillimeter observations are thus essential to select the most luminous high-redshift galaxies. The 850 μm, radio, and redshift data are used to estimate the dust temperatures and characterize photometric redshifts. Using 450 μm measurements for a subset of our sample, we confirm that a median dust temperature of Td = 36 ± 7 K, derived on the assumption that the local far-infrared (FIR)-radio correlation applies at high redshift, is reasonable. Individual 450 μm detections are consistent with the local radio-FIR relation holding at z ~ 2. This median Td is lower than that estimated for similarly luminous IRAS 60 μm galaxies locally. We demonstrate that dust temperature variations make it impossible to estimate redshifts for individual SGMs to better than Δz ≃ 1 using simple long-wavelength photometric methods. We calculate total infrared and bolometric luminosities (the median infrared luminosity estimated from the radio is 8.5 × 1012 L☉), construct a luminosity function, and quantify the strong evolution of the submillimeter population across z = 0.5-3.5 relative to local IRAS galaxies. We use the bolometric luminosities and UV-spectral classifications to determine a lower limit to the AGN content of the population and measure directly the varying the contribution of highly obscured, luminous galaxies to the luminosity density history of the universe for the first time. We conclude that bright submillimeter galaxies contribute a comparable star formation density to Lyman break galaxies at z = 2-3, and including galaxies below our submillimeter flux limit, this population may be the dominant site of massive star formation at this epoch. The rapid evolution of SMGs and QSO populations contrasts with that seen in bolometrically lower luminosity galaxy samples selected in the rest-frame UV and suggests a close link between SMGs and the formation and evolution of the galactic halos that host QSOs.