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THE STUDY OF A MAGNETIC FIELD STRUCTURE IN BLAZAR JETS BY OPTICAL PHOTOPOLARIMETRIC DATA
Yu.S. Efimov1 , E.Yu. Vovk
1 2

RSI "Crimean Astrophysical Observatory", Nauchny, Crimea, 98409, Ukraine 2 National State University, Kiev, 01033, Ukraine Yuri.Efimov@mail.ru

There are no direct metho ds to measure magnetic field intensity in sources of synchrotron radiation. Usually estimations of magnetic field intensity are obtained from the Faraday rotation measure in radio region with additional data ab out a path length and an electron density. Besides the Faraday rotation of p olarization plane there are observational parameters which are connected directly with the intensity of magnetic field and its structure: a p olarization degree and a sp ectral index. Both these parameters can b e obtained from optical observations. On the other hand, various theoretical mo dels connect magnetic field intensity with p olarization degree. From two p olarimetric mo des observed in blazars: circular and linear, the last one is rather large (from 1% to 40%) and can b e detected easily in contrast to the circular p olarization which is very small (fraction of p ercentage). In its turn, the linear p olarization is directly connected with sp ectral index. So, the comparison of theoretical predictions from various mo dels of magnetic field with observed dep endencies b etween p olarization degrees and sp ectral indices allows to significantly confine an uncertainty of the magnetic field intensity estimations. The first such attempt had b een made ab out 30 years ago by Nordsieck (1976). Moreover, such a comparison allows to follow the variations of the magnetic field intensity from observed variations of p olarization degree and sp ectral index. In this rep ort we present a result of such comparison for two well-known blazars 3C 66A and OJ 287. It was shown that in b oth sources the decrease of p olarization and sp ectral index indicate: an increasing disorder of magnetic fields of relativistic jets. References Nordsieck K.H.: ApJ, 1976, 209, 653.