Deep Spitzer 24 mic COSMOS成像-- I.发光尘埃星系的演化--面对模型
Deep Spitzer 24mic COSMOS imaging -- I. The evolution of luminous dusty galaxies - Confronting the models
摘要：
我们提出了在S24>~ 80 μ Jy的COSMOS场的24 mic观测中识别~ 30，000个源的第一个结果。使用精确的photo-z和外推的计数在微弱的流量，我们解决了前所未有的细节积累的中红外背景在宇宙年龄。我们发现24 mic背景强度的~50%和~80%分别来自z<~1和z<~2的星系，支持了在非常高的红移（z>~2）下高度遮蔽源对CIB的贡献很小的假设。假设在光学波长的通量有限的选择，我们还发现，i波段源的部分与24 mic检测强烈增加到z~2的快速演化的结果，恒星形成星系经历了回望时间。尽管如此，这种上升的趋势显示了一个明显的突破，在z~1.3，可能是由于k-校正效应暗示的复杂性的SED中IR。最后，我们比较了我们的结果与不同模型的预测星系形成。我们注意到，半解析形式主义未能再现红移分布在24 mic观察。此外，模拟的星系表现出的R-K色比观测到的蓝得多，预测的K带通量在z>0.5时被系统地低估了。除非这些差异是由于对灭绝的不正确处理造成的，否则它们可能反映了对具有强恒星形成的高z质量源的预测密度的低估，这将指向模拟中尚未完全控制的更基本的过程。最新的后向演化方案相当好地再现了z~3范围内24 mic源的通量/红移分布，尽管没有一个方案能够在所有红移处完全匹配我们的结果。[摘要]
英文摘要：
We present the first results obtained from the identification of ~30,000 sources in the 24mic observations of the COSMOS field at S24>~80muJy. Using accurate photo-z's and extrapolations of the counts at faint fluxes we resolve with unprecedented detail the build-up of the mid-IR background across cosmic ages. We find that ~50% and ~80% of the 24mic background intensity originate from galaxies at z<~1 and z<~2 respectively, supporting the scenario where highly obscured sources at very high redshifts (z>~2) contribute only marginally to the CIB. Assuming flux-limited selections at optical wavelengths, we also find that the fraction of i-band sources with 24mic detection strongly increases up to z~2 as a consequence of the rapid evolution that star-forming galaxies have undergone with lookback time. Nonetheless this rising trend shows a clear break at z~1.3, probably due to k-correction effects implied by the complexity of SEDs in the mid-IR. Finally, we compare our results with the predictions from different models of galaxy formation. We note that semi-analytical formalisms fail to reproduce the redshift distributions observed at 24mic. Furthermore the simulated galaxies exhibit R-K colors much bluer than observed and the predicted K-band fluxes are systematically underestimated at z>0.5. Unless these discrepancies result from an incorrect treatment of extinction they may reflect an underestimate of the predicted density of high-z massive sources with strong star formation, which would point to more fundamental processes that are still not fully controlled in the simulations. The most recent backward evolution scenarios reproduce reasonably well the flux/redshift distribution of 24mic sources up to z~3, although none of them is able to exactly match our results at all redshifts. [Abridged]
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