Correlated X-ray and radio flux variations in the Seyfert galaxy III Zw 2

Abstract

Results from an analysis of the X-ray observations of the Seyfert 1 galaxy / quasar III Zw2, made at four different times during June, 1979 to December, 1980 with the Imaging Proportional Counter (IPC) and the Monitor Proportional Counter (MPC) on the Einstein Observatory are presented. A large decrease in the X-ray intensity of III Zw2 is detected over a one and a half year period, being by a factor of about 8 in 0.1-4 keV band and a factor of about 6 in 1.2-10.2 keV band. Contemporaneous radio observations at 14.5 GHz by Aller et al showed a correlated decline in its radio flux from a value of about 3 Jy in June 1979 to 1.2 Jy in Dec. 1980. Spectral analysis indicates that a power law with spectral index αE = 0.7 describes the spectrum of III Zw2 from 0.1-10 keV rather well. Its composite spectrum from radio to the X-ray bands indicates presence of a spectral break at near-infrared region (~10¹⁴ Hz). Synchrotron self-Compton model is examined to explain the observed characteristics of III Zw2.