High-redshift radio galaxies and quasars at submillimetre wavelengths: assessing their evolutionary status
High-redshift radio galaxies and quasars at submillimetre wavelengths: assessing their evolutionary status
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亚毫米波长的高红移射电星系和类星体：评估它们的演化状态
DOI：
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发表时间：
1997
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影响因子：
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通讯作者：
S. Rawlings
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作者：
D. Hughes;J. Dunlop;S. Rawlings
我们提出了在红移$z = 0.75 - 4.26$对9个射电星系和4个射电安静类星体样本的亚毫米连续辐射研究的新结果。观测是在800 $\mu m$进行的，使用詹姆斯·克拉克·麦克斯韦望远镜（JCMT）上的单元素辐射热计UKT14，达到了典型的r.m.s.灵敏度$\sigma_{rms} \sim 4$ mJy，代表了迄今为止最深的亚毫米河外测量。实现了三个检测，其中两个是安全的（4C41.17, Dunlop et al.（1994）和H1413 $+$ 117），一个（53W002）是暂定的，而其余10个源中的7个获得了类似的上限。我们使用这些数据作为详细讨论从亚毫米和毫米连续通量到高红移的尘埃/气体质量和恒星形成速率的转换的动机，并从我们自己和其他高红移射电星系和类星体的数据中确定这些数量。我们特别研究了从这些数据中得出物理量的四个主要不确定性来源的影响，即i)星系卷云的潜在污染，ii)尘埃静止频率质量吸收系数值的不确定性，iii)限制尘埃温度的困难，以及iv)估计高红移物体中适当的气尘比。我们的讨论强调了量化的重要性，并在可能的情况下尽量减少这种不确定性（例如，通过适当的观测策略），以便充分利用即将到来的下一代测辐射热计阵列（如JCMT上的SCUBA）提供的灵敏度提高十倍。
We present new results of a study of the sub-millimetre continuum emission from a sample of 9 radio galaxies and 4 radio-quiet quasars at redshifts $z = 0.75 - 4.26$. The observations were made at 800$\mu m$, using the single-element bolometer UKT14 on the James Clerk Maxwell Telescope (JCMT), reaching a typical r.m.s. sensitivity of $\sigma_{rms} \sim 4$ mJy and represent some of the deepest submillimetre extragalactic measurements made to date. Three detections were achieved, of which two are secure (4C41.17, Dunlop et al. (1994) and H1413$+$117) and one (53W002) is tentative, whilst comparable upper-limits were obtained for 7 of the 10 remaining sources. We use these data as the motivation for a detailed discussion of the conversion from submillimetre and millimetre continuum fluxes to dust/gas masses and star formation rates at high-redshift, and determine these quantities from our own and other data on high-redshift radio-galaxies and quasars. In particular we have investigated the impact of the four main sources of uncertainty in deriving physical quantities from such data, namely i) potential contamination by galactic cirrus, ii) uncertainty in the value of the dust rest-frequency mass-absorption coefficient, iii) difficulty in constraining the dust temperature, and iv) estimation of the appropriate gas:dust ratio in high-redshift objects. Our discussion emphasises how important it will be to quantify and, where possible, minimize such uncertainties (via, for example, appropriate observational strategies) in order to fully capitalize on the ten-fold improvement in sensitivity offered by the imminent arrival of the next generation of bolometer arrays, such as SCUBA on the JCMT.