SOME ACTIVE GALACTIC NUCLEI AS COSMOLOGICAL PROBES

A method of using AGNs as cosmological probes and some recent results are discussed. The method is based on fitting the Hedgehog model to ob servations of spectra, structure and polarization of AGN radio emissio n and time variations of the observed quantities. If red shifts of sel ected AGNs are known, extragalactic distances, the Hubble constant and the deceleration parameter of the Universe can be measured using only radio observations. Recent results may give new strong arguments for the basic model to be in agreement with observations of variable spect ra and structure of many AGNs, and may allow preliminary selection of AGNs for further use.