Variability and circular polarisation in the nucleus of NGC5128 at 10.7 GHz

Centaurus A

“…The "shells" and extensions of luminous material are especially prominent along the galaxy's major axis. infrared hot spot (Wade et al 1971) has been reported to be variable at millimeter wavelengths on short (~ Id) time scales (Kellermann 1974;Kaufmann et al 1977;Beall et al 1978;Kaufmann and Raffaelli 1979;Kaufmann and Beall 1980;Dent andHobbs 1983, quoted in Burns, Feigelson, andSchreier 1983; but see Fogarty and Schuch 1975), and at longer wavelengths on longer (~ 1 week) time scales (Price and Stull 1975;Price and Graf 1978), but not on short time scales at centimeter wavelengths (Bums et al 1983). The nucleus is extremely compact; Kellermann et al (1975) detected structure at ~ 7 X 10 -3 arc sec (0.1-0.2 pc) and VLBI structure at 5 X 10 -4 arc sec (~ 0.01 pc) has been detected at 8 GHz (Jauncey et al 1983, quoted in Preston et al 1983.…”

Gamma-Ray Astronomy

“…In Figure 4 we combined such observations with the gamma-ray observations for the three active galaxies from which gamma rays were seen. For Centaurus A, the radio measurements are from Kellermann (1974) , Price & Stull (1975), and Beall et al (1978; the infrared data are from Grasdalen & Joyce (1976) ; the optical measurements are from Kunkel & Bradt (1971); the x-ray and gamma-ray results up to a few MeV are from the HEAO-1 observations of Baity et al (1981); the gamma-ray upper limits around 100 MeV are from the SAS-2 observations of Bignami et al (1979); and the gamma ray measurement above a few hundred Ge V is from the atmospheric Cerenkov light observations of Grindlay et al (1975). For NGC 4151 the radio observations are from Haynes et al (1975), the IR and visible data are from Rieke & Lebofsky (1979) ; the x-ray and gamma-ray data and limits up to several MeV are from the summary of White et al (1980); and the gamma-ray limits at -100 MeV and -100 GeV are, respec tively, from Bignami et al (1979) andPorter &Weekes (1979).…”