Radio Polarization and Spectra of Variable Extragalactic Objects

使用密歇根26米射电望远镜，将在4.8、8.0和14.5 GHz的频率上频繁地测量河外射电源的总通量密度和线偏振。将建立理论模型并将其与这些数据进行拟合，以研究发射区的物理条件和粒子能量产生机制。这些观测将得到与其他研究人员合作的甚长基线干涉测量(VLBI)观测的补充。还将利用国家射电天文台91米望远镜在0.85、1.4和2.7 GHz进行观测，以研究低频可变源的宽带特性。研究的具体目标包括：a)获得孤立爆发的高时间分辨率、多频率偏振和通量密度数据，以便测试源发射区的详细理论模型，b)建立更复杂的激波在相对论喷流中传播的模型，该模型约束了发射区的更多物理参数，C)为了更好地了解作为分米变化原因的内在和外在机制的相对重要性，以及“中频差”的性质，d)通过同时的宽带(紫外线或X射线通过射电波长)观测来改进活动星系核的全球模型，以及e)获得所选源的形态信息以测试发射区的模型。

Frequent measurements of the total flux density and linear polarization of extragalactic radio sources will be made at a frequency of 4.8, 8.0 and 14.5 GHz using the Michigan 26 meter radio telescope. Theoretical models will be developed and fitted to these data to study the physical conditions in the emitting regions and to study the particle energy generation mechanisms. These observations will be supplemented by Very Long Baseline Interferometry (VLBI) observations in collaboration with other researchers. Observations will also be made at 0.85, 1.4 and 2.7 GHz with the National Radio Astronomy Observatory 91 meter telescope to investigate the broad-band characteristics of low- frequency variable sources. Specific objectives of the research include: a) to obtain high time-resolution, multifrequency polarization and flux density data of isolated outbursts in order to test detailed theoretical models of the source emitting region, b) to develop more sophisticated models of shocks propagating in relativistic jet flows which constrain more of the physical parameters of the emitting regions, c) to better understand the relative importance of intrinsic and extrinsic and mechanisms as causes of decimetric variability, and the nature of the "intermediate frequency gap" , d) to improve global models of active galactic nuclei through simultaneous, broad- band (Ultraviolet or X-ray through radio wavelengths) observations, and e) to obtain morphological information of selected sources to test models of the emitting regions.