射电天文研究室知识库

We report the progress on Very Long Baseline Interferometry (VLBI) observations of Gigahertz Peaked Spectrum (GPS) radio sources, and single-dish observations of active galactic nuclei (AGNs). The GPS sources are a kind of young AGNs observable in radio. From our VLBI observations at 1.6 and 5 GHz with the European VLBI Network (EVN) including the Urumqi and Shanghai stations, most GPS sources show compact doubles with sizes less than 1 kiloparsec. We have classified the sources into double-lobes, core-jets, and complex structures according to the spectral indices as well as images. We also estimated the values of the jet viewing angle for the symmetric objects. In addition, we are monitoring a few samples of AGNs with the Urumqi 25-meter radio telescope, in order to find flux variability. We detected rapid flux variability in quasar 1156+295, and relatively slow variability in a few of the others. The origin of the rapid variability is discussed. Moreover, we launched a radio-optical monitoring program called Fermi-AGN in 2009.