Optical spectroscopy and polarization of a new sample of optically bright flat radio spectrum sources
Optical spectroscopy and polarization of a new sample of optically bright flat radio spectrum sources
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DOI：
10.1093/mnras/281.2.425
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发表时间：
1996-07
影响因子：
4.8
通讯作者：
M. Marchã;I. Browne;C. Impey;Paul S. Smith
中科院分区：
文献类型：
--
作者：
M. Marchã;I. Browne;C. Impey;Paul S. Smith
本文讨论了一个新的8.4GHz亮平射电源样品，它由亮度大于V = 17的天体组成。选择样本有三个目的：（i）找到低光度的BL Lacertae（BL Lac）天体，其射电光度可与在X射线频率下选择的BL拉克天体的射电光度相媲美;（ii）研究BL拉克和其他平坦射电频谱源之间的差异;以及（iii）定义附近射电大声天体的样本，其宿主星系易于研究。利用射电偏振、光学偏振百分比、破裂对比度和最强发射线的等效宽度等四个观测参数，我们比较了BL拉克与样品中发现的其他类型活动星系核（AGN）的性质。我们发现大多数天体都有弱的发射线，但也发现了一些具有Seyfert型光谱的源，只有少数例外，这两种类型的源在观测性质上是分离的。在研究的对象中，我们报告了10个新的BL拉克和BL Lac候选者，我们定义了一个“完整”的样本，由这些对象组成的明亮的平坦的无线电频谱源的红移：：; 0.1。
A new sample of bright fiat radio spectrum sources selected at 8.4 GHz and consisting of objects brighter than V = 17 is discussed. The sample was selected with three purposes in mind: (i) to find low-luminosity BL Lacertae (BL Lac) objects with radio luminosities comparable to those of BL Lacs selected at X-ray frequencies; (ii) to investigate the differences between BL Lacs and other fiat radio spectrum sources; and (iii) to define a sample of nearby radio-loud objects, the host galaxies of which are easy to study. Using information on four observational parameters, radio polarization, optical percentage polarization, break contrast and equivalent width of the strongest emission line, we compare the properties of BL Lacs with those of other types of active galactic nuclei (AGN) found in the sample. We find that most of the objects have weak emission lines although some sources with Seyfert-type spectra were also found. With only a few exceptions, the two types of sources appear well separated in their observational properties. Among the objects studied we report 10 new BL Lacs and BL Lac candidates, and we define a 'complete' sample of bright fiat radio spectrum sources that consists of those objects with redshift ::; 0.1.