Probing high-redshift quasars with ALMA. I. Expected observables and potential number of sources
Probing high-redshift quasars with ALMA. I. Expected observables and potential number of sources
复制标题
使用 ALMA I 探测高红移类星体 预期可观测值和潜在源数量
DOI：
10.1051/0004-6361/200913467
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发表时间：
2010
影响因子：
6.5
通讯作者：
Ralf S. Klessen
中科院分区：
文献类型：
--
作者：
Dominik R.G. Schleicher;Marco Spaans;Ralf S. Klessen
目的我们探索ALMA观测如何以前所未有的细节探测高红移星系。我们讨论了大尺度星暴激发的主要观测数据，并提出了对活动星系中心的化学和通量的预期，其中化学可能是由X射线的吸收驱动的。我们估计了
深场中高红移源的预期数目。作为对亚毫米线观测的复杂解释的具体例子，我们分析了最近探测到的dz=6.42类星体，它的一些不同的线通量已经可用。我们注意到，我们的诊断也可能对未来用Spica或FIRI等星载仪器在局部宇宙中进行观测很有价值。方法为了估计星暴的可观测性，我们检查了如果星系z=8，附近Seyfert 2星系NGC-1068的星爆环发出的辐射属于ALMA带。我们基于半解析模型估计了中心X射线主导区的大小，并使用详细的一维方法来评估X射线辐照分子云中的化学和预期的线发射。我们利用已有的X射线主控区的化学计算，给出了不同的谱线通量与X射线光度、云密度和云柱密度的关系。我们使用高Z黑洞布居和局域SMBH密度的理论模型来估计高红移处的源的数量。结果表明，一些不同的精细结构线可以用来相当详细地探测高红移类星体的星暴分量，通过几种独立的手段提供关于这些星系结构的具体信息。我们证明了中心X射线主导区的大小约为几百秒，并对CO、[CII]和[OI]中的预期通量进行了详细的预测。虽然后者的精细结构谱线迅速变得光学厚度很大，主要取决于X射线源的强度，但旋转的CO谱线对这些参数有很大的依赖关系。我们将我们的模型与在NGC-1068和APM-08279中观测到的XDR进行了比较，发现观测到的发射确实可以用这些模型解释。根据X射线通量的不同，CO谱线强度可能会持续上升，直到(17-16)跃迁。对这种高J线的测量使人们能够在观测上区分XDR和PDR。对于最近观测到的z=6.42类星体，我们发现收集到的通量不能用单一的气体成分来解释。我们发现有迹象表明，在活跃的恒星形成区域存在密集的暖分量，而在较安静的区域存在低密度分量。Nearz=6，ALMA深场可能会在每个arcmin2中大致找到一个震源。在红移较高的情况下，人们可能不得不依靠JWST等其他调查来寻找合适的来源。
AimsWe explore how ALMA observations can probe high-redshift galaxies in unprecedented detail. We discuss the main observables that are excited by the large-scale starburst, and formulate expectations for the chemistry and the fluxes in the center of active galaxies, in which chemistry may be driven by the absorption of X-rays. We estimate the expected number of sources at high redshift in
an ALMA deep field.
As a specific example for the complex interpretation of sub-mm line observations, we analyze the recently detectedz = 6.42quasar, for which a number of different line fluxes is already available. We note that our diagnostics may also be valuable for future observations in the local universe with space-borne instruments like on SPICA or FIRI.MethodsTo estimate the observables from the starburst, we check which emission from the starburst ring of the nearby Seyfert 2 galaxy NGC 1068 falls into the ALMA bands if the galaxy were placed atz = 8. We estimate the sizes of the central X-ray dominated region based on a semi-analytic model, and employ a detailed 1D approach for the chemistry in X-ray irradiated molecular clouds to evaluate the chemistry and the expected line emission under these conditions. We make use of pre-existing chemistry calculations in X-ray dominated regions to show the dependence of different line fluxes on X-ray luminosity, cloud density and cloud column density. We use theoretical models for the high-zblack hole population and the local SMBH density to estimate the number of sources at higher redshift.ResultsWe show that a number of different fine-structure lines may be used to probe the starburst component of high-redshift quasars in considerable detail, providing specific information on the structure of these galaxies by several independent means. We show that the size of the central X-ray dominated region is of the order of a few hundred parsec, and we provide detailed predictions for the expected fluxes in CO, [CII] and [OI]. While the latter fine-structure lines quickly become optically thick and depend mostly on the strength of the X-ray source, the rotational CO lines have a non-trivial dependence on these parameters. We compare our models to XDRs observed in NGC 1068 and APM 08279 and find that the observed emission can indeed be explained with these models. Depending on the amount of X-ray flux, the CO line intensities may rise continuously up to the (17-16) transition. A measurement of such high-Jlines allows one to distinguish observationally between XDRs and PDRs. For the recently observedz = 6.42quasar, we show that the collected fluxes cannot be interpreted in terms of a single gas component. We find indications for the presence of a dense warm component in active star forming regions and a low-density component in more quiescent areas. Nearz = 6, an ALMA deep field may find roughly one source per arcmin2. At higher redshift, one likely has to rely on other surveys like JWST to find appropriate sources.
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DOI：
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发表时间：
2008
期刊：
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documentclass{aastex} usepackage{amsbsy} usepackage{amsfonts} usepackage{amssymb} usepackage{bm} usepackage{mathrsfs} usepackage{pifont} usepackage{stmaryrd} usepackage{textcomp} usepackage{ 的观察
DOI：
--
发表时间：
1999
期刊：
影响因子：
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作者：
B. McCall;T. Geballe;K. Hinkle;T. Oka
通讯作者：
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DOI：
10.1086/428495
发表时间：
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影响因子：
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作者：
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