标题： 高红移毫米波段搜索中分子吸收的缺失 显示英文标题

标题： On the absence of molecular absorption in high redshift millimetre-band searches

摘要： 我们对红化射电源宿主星系的毫米波段吸收（通过CO和HCO+旋转跃迁）进行了搜索（z = 0.405-1.802）。尽管有颜色选择（除一个源外，所有源的V - K > 5），但在检测到背景连续谱通量的八个类星体中均未发现吸收。基于之前（主要是中间）的H2和OH检测，此处以及一些之前的调查的限制应该足够深，可以根据它们的V - K颜色检测分子吸收。然而，我们的调查假设红化与类星体发射红移附近的尘埃有关，并且该发射的窄毫米波成分被紧凑的分子核心拦截。通过使用已知的毫米波吸收体来定义颜色深度，并将其与源的紫外光度进行比较，我们发现，即使这些假设成立，四十个物体中只有十二个（主要是本工作中的）可能被检测到。假设在z=0时激发温度为10 K，随着温度的升高，数量会减少（在100 K时为零可检测）。 显示英文摘要

摘要： We have undertaken a search for millimetre-wave band absorption (through the CO and HCO+ rotational transitions) in the host galaxies of reddened radio sources (z = 0.405-1.802). Despite the colour selection (optical-near infrared colours of V - K > 5 in all but one source), no absorption was found in any of the eight quasars for which the background continuum flux was detected. On the basis of the previous (mostly intervening) H2 and OH detections, the limits reached here and in some previous surveys should be deep enough to detect molecular absorption according to their V - K colours. However, our survey makes the assumption that the reddening is associated with dust close to the emission redshift of the quasar and that the narrow millimetre component of this emission is intercepted by the compact molecular cores. By using the known millimetre absorbers to define the colour depth and comparing this with the ultra-violet luminosities of the sources, we find that, even if these assumptions are valid, only twelve of the forty objects (mainly from this work) are potentially detectable. This is assuming an excitation temperature of 10 K at z=0, with the number decreasing with increasing temperatures (to zero detectable at 100 K).