Dense Structure. Blazar Source And The Light Changed

Blazars, one part of Active Galactic Nuclei (AGN), are the most powerful and the largest amplitude variable objects in the cosmos. According to the standard unified model of AGN, there is a central massive black hole, surrounded by an accretion disk. A powerful reletivistic jet will emanate from the region near the black hole. The viewing angle of the jet of blazar is very small. Thus, its radiation will be Doppler enhanced, and generate a wide spectrum from radio band to light energy -y-ray band. To study how blazars?energy originates, transfers and variates is very important to cosmology and basic physics. After world war II, there was a big progress in radio astronomy. It brought on some great discoveries in astronomy, such as quasar, microwave background radiation etc. In radio astronomy, interferometry is an important technique which is still under developing. Today, VLBI (Very Long Baseline Interferometry) can reach sub-milliarcsecond angular resolution. It is the only tool that can be used to study the compact strutures of blazars. Furthermore, some radio telescopes were systematically monitoring the fluxes of blazars since 1960s. We have many data of the light curves of blazars now. The main purpose of this dissertation is to study the compact structures and light curves of blazars depend on the observation of single dish and VLBI. We applied EVN (European VLBI Network) and VLBA to observe blazar 0420-014, 1334-127, 1504-166, 2243-166, 2345-167 and J1625+4134. We com- pared their compact structures on different epochs, measured the superluminal proper motions of their jet components, and studied the relation between the emanation of new jet component and flux flare. I found that 0420-014 had two kinds of radio flares which orignated in different positions in jet. Moreover, I found some evidence that the jet of PKS 0420-014 was probably rotating (Chap- ter 3 and 4). Also, I proposed a new method to estimate the viewing angles of the jets of blazars. This method is based on multi-epoch VLBI observation, and can obtain not only viewing angle but also its variation (Chapter 5). The periodicity analysis of the light curves of blazars needs improvement. Due to the complication of blazars?light curves, the present periodicity analysis methods are not perfect. In the rest part of this dissertation (Chapter 6 and 7), I disscussed in detail some suitable periodicity analysis method, i.e. CLEANmethod, MaJximum entropy method (MEM) and Jurkevich method. I improvedthe Jurkevich method. FOr each method, I compiled a corresponding softwarewhich could process real data. Combined CLEAN idea with Jurkevich method,I proposed a method, called periodical function CLEAN algorithm, to pick-upperiodical signals from original lightcurves. The obtained periodic signals arevery helpful to understand their physical mechanism.