A new look at the infrared properties of z ∼ 5 galaxies
A new look at the infrared properties of z ∼ 5 galaxies
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重新审视 z 〜 5 星系的红外特性
DOI：
10.1093/mnras/stac2997
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发表时间：
2022
影响因子：
4.8
通讯作者：
A. Faisst
中科院分区：
文献类型：
--
作者：
L. Sommovigo;A. Ferrara;S. Carniani;A. Pallottini;P. Dayal;E. Pizzati;M. Ginolfi;V. Markov;A. Faisst
最近的阿尔马大型巡天发现，在z > 4的恒星形成星系中存在着显著的尘埃连续辐射。不幸的是，这样的大型程序--即ALPINE（z 105）和REBELS（z 107）--只为我们提供了单个目标的远红外（FIR）连续数据点。因此，高z星系FIR谱能量密度（SED）大多保持不受约束，取决于SED拟合过程中尘埃温度（Td）的假设。这在推断的尘埃质量（Md）、红外光度（LIR）和z > 4时的模糊星星形成率（SFR）分数中引入了不确定性。在这项工作中，我们使用的方法，使我们能够约束Td与一个单一的频带测量相结合的158 μm连续信息与上覆的[C $\scriptstyle \rm II$]发射线。我们分析了21个[C $\scriptstyle \rm II$]和FIR连续谱在ALPINE中检测到的z × 105个星系，发现Td = 25 − 60 K和Md = 0.6 − 25.1 × 107 M。根据测量到的阿尔卑斯星系的恒星质量，推断出的尘埃产量约为Md/M =（0.2 − 8）× 10−3，与理论上的尘埃产量限制一致。我们发现21个ALPINE星系中有8个的LIR ≥ 1012 L，与超亮红外星系（ULIRGs）相当。依赖于紫外到光学SED拟合，在这8个ULIRGs类星系中的4个中，SFR被低估了2个数量级。我们的结论是，这4个奇特的源的特点应该是一个两相星际介质结构与“空间隔离”FIR和紫外线发射区。
Recent ALMA large surveys unveiled the presence of significant dust continuum emission in star-forming galaxies at z > 4. Unfortunately, such large programs – i.e. ALPINE (z ∼ 5) and REBELS (z ∼ 7) – only provide us with a single Far-Infrared (FIR) continuum data point for their individual targets. Therefore, high-z galaxies FIR spectral energy densities (SEDs) remain mostly unconstrained, hinging on an assumption for their dust temperature (Td) in the SED fitting procedure. This introduces uncertainties in the inferred dust masses (Md), infrared luminosities (LIR), and obscured Star Formation Rate (SFR) fraction at z > 4. In this work we use a method that allows us to constrain Td with a single band measurement by combining the 158 μm continuum information with the overlying [C $\scriptstyle \rm II$] emission line. We analyse the 21 [C $\scriptstyle \rm II$] and FIR continuum detected z ∼ 5 galaxies in ALPINE, finding a range of Td = 25 − 60 K and Md = 0.6 − 25.1 × 107 M⊙. Given the measured stellar masses of ALPINE galaxies, the inferred dust yields are around Md/M⋆ = (0.2 − 8) × 10−3, consistent with theoretical dust-production constraints. We find that 8 out of 21 ALPINE galaxies have LIR ≥ 1012 L⊙, comparable to UltraLuminous IR Galaxies (ULIRGs). Relying on ultraviolet-to-optical SED fitting, the SFR was underestimated by up to 2 orders of magnitude in 4 of these 8 ULIRGs-like galaxies. We conclude that these 4 peculiar sources should be characterised by a two-phase interstellar medium structure with “spatially-segregated” FIR and ultraviolet emitting regions.