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Full-Text Articles in Physical Sciences and Mathematics
Observations Of Two Peculiar Emission Objects In The Large Magellanic Cloud, Menas Kafatos, A. G. Michalitsianos, D. A. Allen, R. E. Stencel
Observations Of Two Peculiar Emission Objects In The Large Magellanic Cloud, Menas Kafatos, A. G. Michalitsianos, D. A. Allen, R. E. Stencel
Mathematics, Physics, and Computer Science Faculty Articles and Research
Ultraviolet and visual wavelength spectra were obtained of two peculiar emission objects, Henize S63 and Sanduleak.'s star in the Large Magellanic Cloud. Previously not observed in the near- or far-ultraviolet, both objects exhibit strong permitted and semiforbidden line emission. Estimates based on the absolute continuum flux of the hot companion star in Hen S63 indicate that it rivals the luminosity of the carbon star primary. The emission-line profile structure in both objects does not suggest Wolf-Rayet type emission. Carbon in Sanduleak.'s star (LMC anonymous) is conspicuously absent, while N v, N IV], and N III] dominate the UV emission-line spectrum. …
The High-Energy Spectrum Of Hot Accretion Disks, J. A. Eilek, Menas Kafatos
The High-Energy Spectrum Of Hot Accretion Disks, J. A. Eilek, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
A hot, two-temperature accretion disk can be a strong γ-ray and relativistic particle source. This occurs when the accretion rate is high enough -- M/ M ≥ 3 X 10^-9 α γr^-1 for a canonical Kerr black hole-due to the high ion temperature in the inner disk. We present detailed photon and particle spectra for specific disk models. The predicted γ-ray flux is as high as 10% of the bolometric luminosity in sub-Eddington models. Most of the γ-radiation is continuous, due to the π^0 decay, emitted around 100 MeV but degraded to a few MeV in optically thick models. Spectral …
Gamma Rays From Penrose Powered Black Holes In Centaurus A, 3c 273, And Ngc 4151, Menas Kafatos
Gamma Rays From Penrose Powered Black Holes In Centaurus A, 3c 273, And Ngc 4151, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
Gamma-ray observations of active galaxies have important consequences for theories of the activity in their nuclei. The observations of Cen A, 3C 273, and NGC 4151 are examined under the assumption that Penrose collision processes in the ergospheres of massive black holes power their nuclei. The observed sharp break in the MeV region of the NGC 4151 spectrum cannot be due to the γ-γ pair production process. We attribute this break to the Penrose Compton scattering (PCS), in which γ-rays escape from the ergosphere as a result of Penrose processes involving electrons and lower energy X-ray photons in the ergosphere …