The expected detection of dust emission from high-redshift Lyman α galaxies
The expected detection of dust emission from high-redshift Lyman α galaxies
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预期检测到高红移莱曼α星系的尘埃排放
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
N. Pirzkal
中科院分区：
文献类型：
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作者：
S. Finkelstein;S. Malhotra;J. Rhoads;N. Hathi;N. Pirzkal
最近的结果表明，高红移莱曼 a (Lya) 星系的很大一部分含有大量尘埃。这意味着莱亚星系并不像过去所认为的那样是原始的。然而，这种粉尘尚未在排放中直接检测到；相反，它是根据静止框架紫外线（UV）和光学观测的消光估计推断出来的。这可能很棘手，因为尘埃和老恒星都会使用于推断尘埃的波长的银河光谱变红。因此，直接测量这些星系的尘埃排放是估计尘埃总质量的更准确方法，为我们提供了有关恒星种群和星际介质富集的真实物理信息。新一代仪器，例如阿塔卡马大型毫米波阵列和亚毫米波阵，应该能够探测到其中一些星系的亚毫米级尘埃排放。利用紫外光谱斜率的测量，我们得出了 23 z ≥ 4 Lya 星系样本的远红外通量预测。我们发现，在短短几个小时内，我们就可以检测到 39% ± 22% 的 Lya 星系的尘埃排放。将这些结果与从 21 个莱曼断裂星系 (LBG) 样本中发现的结果进行比较，我们发现 LBG 被检测到的可能性平均比 Lyα 星系高 60%，这意味着它们的尘埃较多，从而表明这些天体之间存在进化差异。这些观测结果将为这些星系中的尘埃提供比仅从紫外线和光通量得出的观测结果更好的约束。这些星系中存在尘埃的无可否认的证据可以解释今天许多 Lya 星系中所看到的比预期更大的 Lya 等效宽度。
Recent results have shown that a substantial fraction of high-redshift Lyman a (Lya) galaxies contain considerable amounts of dust. This implies that Lya galaxies are not primordial, as has been thought in the past. However, this dust has not been directly detected in emission; rather it has been inferred based on extinction estimates from rest-frame ultraviolet (UV) and optical observations. This can be tricky, as both dust and old stars redden galactic spectra at the wavelengths used to infer dust. Measuring dust emission directly from these galaxies is thus a more accurate way to estimate the total dust mass, giving us real physical information on the stellar populations and interstellar medium enrichment. New generation instruments, such as the Atacama Large Millimeter Array and Sub-Millimeter Array, should be able to detect dust emission from some of these galaxies in the submillimeter. Using measurements of the UV spectral slopes, we derive far-infrared flux predictions for of a sample of 23 z ≥ 4 Lya galaxies. We find that in only a few hours, we can detect dust emission from 39 ± 22 per cent of our Lya galaxies. Comparing these results to those found from a sample of 21 Lyman break galaxies (LBGs), we find that LBGs are on average 60 per cent more likely to be detected than Lyα galaxies, implying that they are more dusty, and thus indicating an evolutionary difference between these objects. These observations will provide better constraints on dust in these galaxies than those derived from their UV and optical fluxes alone. Undeniable proof of dust in these galaxies could explain the larger than expected Lya equivalent widths seen in many Lya galaxies today.