论文标题
FR0射电星系的Lofar视图
The LOFAR view of FR0 radio galaxies
论文作者
论文摘要
我们探讨了Fanaroff-Riley Class 0目录（FR0CAT）中源的低频无线电性能，如低频阵列（Lofar）观测值150 MHz所示。该样本包括与附近（z <0.05）大型早期型星系相关的104个紧凑型无线电主动核（AGN）。 Lofar观察到的66个FR0CAT源位于天空区域中，所有这些源都被检测到，通常显示出小于3-6 kpc的点状结构。然而，低表面亮度的12 fr0分解的发射占150 MHz的总无线电功率的5％至40％，通常具有喷射的形态在15至50 kpc之间。在其他FR0周围未检测到延长的发射，典型的光度限制为5 x 10 $^{22} $ w/hz在100 kpc x 100 kpc的面积上。 150 MHz至1.4 GHz之间的FR0的频谱斜率范围广泛（-0.7 <$α$ <0.8），中位值为$ \overlineα\ sim 0.1 $;其中有20％的频谱（$α$> 0.5），这表明存在于空间分辨率限制内的大量扩展。通过包括光谱和形态学信息，FR0的比例显示了射流的证据，至少约为40％。这项研究证实，FR0和Fris可以被解释为连续的喷射源人群的两个极端，而FR0代表了尺寸和无线电功率的低端。
We explore the low-frequency radio properties of the sources in the Fanaroff-Riley class 0 catalog (FR0CAT) as seen by the LOw Frequency ARray (LOFAR) observations at 150 MHz. This sample includes 104 compact radio active galactic nuclei (AGN) associated with nearby (z<0.05) massive early-type galaxies. Sixty-six FR0CAT sources are in the sky regions observed by LOFAR and all of them are detected, usually showing point-like structures with sizes smaller than 3-6 kpc. However, 12 FR0s present resolved emission of low surface brightness which contributes between 5% and 40% of the total radio power at 150 MHz, usually with a jetted morphology extending between 15 and 50 kpc. No extended emission is detected around the other FR0s, with a typical luminosity limit of 5 x 10$^{22}$ W/Hz over an area of 100 kpc x 100 kpc. The spectral slopes of FR0s between 150 MHz and 1.4 GHz span a broad range (-0.7 < $α$ < 0.8) with a median value of $\overlineα\sim 0.1$; 20% of them have a steep spectrum ($α$ > 0.5), an indication of the presence of substantial extended emission confined within the spatial resolution limit. The fraction of FR0s showing evidence for the presence of jets, by including both spectral and morphological information, is at least ~40%. This study confirms that FR0s and FRIs can be interpreted as two extremes of a continuous population of jetted sources, with the FR0s representing the low end in size and radio power.
