期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 386, 期 3, 页码 1729-1738出版社
WILEY-BLACKWELL
DOI: 10.1111/j.1365-2966.2008.13161.x
关键词
galaxies; active; quasars; general; cosmic microwave background; radio continuum; galaxies
We present an analysis of the spectral properties of the extragalactic radio sources in the nearly complete Very Small Array (VSA) sample at 33 GHz. Data from different surveys are used to study source spectra between 1.4 and 33 GHz. We find that, in general, spectra cannot be well described by a single power law in the range of frequencies considered. In particular, most of the VSA sources that are steep between 1.4 and 5 GHz, show a spectral flattening at nu > 5 GHz. We identify 20 objects (19 per cent of the sample) clearly characterized by an upturn spectrum, i.e. a spectrum falling at low frequencies (nu less than or similar to 5 GHz) and inverted at higher frequencies. Spectra with high-frequency flattening or upturn shape are supposed to occur when the emission from the active galactic nucleus (AGN) compact core begins to dominate over the component from extended lobes. This picture fits well with the AGN unified scheme, for objects observed at intermediate viewing angles of the AGN jet. Finally, we discuss implications that this class of sources can have on future cosmic microwave background observations at high resolution.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据