Milliarcsecond scale compactness of extragalactic radio sources at cosmological distances Original Research Article

A combination of VSOP pre-launch survey data and our own observations of extremely high redshift quasars provides a data base for studying structural properties of radio-loud quasars as a class of objects. We concentrate our attention on analyzing the compactness of the sources as a function of their redshift (and therefore the emitting frequency) as a precursor to the use of milliarcsecond scale structures of AGN as a cosmological standard rod. Data from the VSOP Survey program, as well as additional VSOP observations of the most distant quasars will enable us to conduct a similar study on sub-milliarcsecond angular scale in the near future.