Matter content in AGN jets: constraint from cocoon dynamics?

The matter content of jets in active galactic nuclei is examined in a new way. We model the dynamical expansion of its cocoon embedded in the intra-cluster medium (ICM). By comparing the observed shape of the cocoon with that expected from the theoretical model, we estimate the total pressure ($P_{\rm c}$) and electron temperature ($T_{e}$) of the cocoon. The number density of the total electrons ($n_{e^{-}}$) is constrained by using the non-thermal spectrum of the hot spot and the analysis of the momentum balance between the jet thrust and the rum pressure of ICM. Together with the obtained $P_{\rm c}$, $T_{e}$ and $n_{e^{-}}$, we constrain the matter content in the jets. We find that, in the case of Cygnus A, the ratio of number density of protons to that of electrons is of order of $10^{-3}$ . This implies the existence of a large number of positron in the jet.Comment: 4 pages, to appear in the proceedings of "Astrophysical Sources of High Energy Particles and Radiation", Torun, 20-24 June 200

Theoretical and experimental investigations of collective microwave phenomena in solids Semiannual status report, 1 Oct. - 31 Dec. 1969

Theoretical and experimental investigations of collective microwave phenomena in solid

Theoretical and experimental investigations of collective microwave phenomena in solids

Methods of generating microwave shear waves efficiently were studied. A new technique of mode conversion from a longitudinal wave to a shear wave was investigated and virtually 100% conversion efficiency could be obtained. Several aspects of Gunn oscillators were studied. One involved the detailed study of domains in Gunn oscillators using long samples of bulk gallium arsenide. Several new techniques were devised for measuring the properties of the domains. A fundamental theory of the efficiency of a Gunn oscillator was worked out. A computer program was devised to study the transient effect of domains passing through Gunn diodes. Some of the first planar epitaxial Gunn oscillators were made using liquid epitaxial material grown by liquid phase techniques on semi-insulating substrate. A new theory which predicted the properties of RF signals propagating in a thin film layer of GaAs was developed. The theory of the operation of a traveling wave amplifier is described