Tatsuji Kato

VLA Polarization Observation of the Radio ARC at 15 GHZ

Polarization measurements of the radio Arc were made with the VLA at 15 GHz. High frequency polarimetry made with high spatial resolution minimizes Faraday depolarization and reveals polarized filaments which correspond to the predominant filaments of the radio Arc. We notice a peculiar linear feature in the polarization map (“thorns”) which suggests the presence of a second magnetic field system. The total intensity maps show no evidence for an interaction between the two field systems, so the thorns may be foreground magnetized structures. However, if the two magnetic field systems do interact, it would allow a model in which the acceleration of relativistic particles takes place at their intersection. The accelerated particles would flow toward both ends of the radio Arc, and account for the intrinsic polarization observed along the entire length of the system. Thermal electrons responsible for the Faraday depolarization occuring at longer wavelengths may be supplied by the interaction of the streams of relativistic particles with relatively dense, ambient thermal clouds.

Observations of flat-spectrum QSOs at 43 GHz at NRO

Abstract Using the 45-m telescope at NRO we measured flux densities at 43 GHz of 115 flat-spectrum radio sources selected from 5 GHz catalogues. A preliminary log N ∼ log S curve is obtained. A simple model interpretation of the curve is given.

The 10 GHz Log N — Log S Curve Obtained At NRO

Using 45-m radio-telescope at NRO, we obtained log N — log S curves at 10 GHz for flat- and steep-spectrum sources separately. A simple model-fitting of evolution is given

LOG N - LOG S OF RADIO SOURCES AT 10 GHz WITH FLAT SPECTRA*

A log N — log S relation at 10 GHz is constructed for sources with the flat spectra α ≤ 0.5 (flux density S ∞ ν −α) from observations at NRO, MPIfR and others. Based on the source distribution on log (Luminosity) ~ volume plane we obtain an epoch-depending luminosity function, which explains the above relation.