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Joint Astrophysics Colloquium
Charles Dermer Naval Research Laboratory The relationship between different classes of galaxies is revealed in studies of galaxy spectra. In this talk, I describe broadband spectra of luminous and active galaxies. The spectra of blazars, which are radio-loud active galaxies where the jets point towards us, form a "blazar main sequence" that depends on the jet power and intensity of the surrounding radiation field. An evolutionary scenario is proposed that links blazar subclasses in terms of a reduction in the black-hole accretion power with time. Nonthermal proton acceleration in galaxy jets produce neutrinos through photomeson production. Sources with intense surrounding fields should be strong neutrino sources. Neutrons and high-energy photons formed through photomeson processes will transport inner jet energy far from the black hole engine to power distant jets, hot spots and lobes. This effect may account for differences between classes of radio galaxies that display distinct morphologies. Such a scenario may also link radio-loud AGNs with ultraluminous infrared galaxies and optical QSOs, and will be tested with gamma-ray and neutrino telescopes now in development.
Thursday, October 18th 2001, 12:00 |