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  • ASTROPHYSICS  (7)
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  • 1
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    Effects of gamma-ray, neutrino, and particle production on the energetics and dynamics of compact extragalactic radio sources (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Consideration is given to particle production and high-energy radiation within apparently superluminal radio components of extragalactic radio sources forming within the apparent region of nuclear activity of a quasar or active galaxy. The physical conditions in compact components observed as radio emitters are derived for the quasars 3C 273 and 3C 345 and extrapolated to those of initial components of sizes on the order of 10 to the 15th cm on the basis of two-dimensional relativistic jet and relativistic three-dimensional models of component expansion. Probabilities that a given particle avoids an inelastic collision in the relativistic plasma are calculated for both cases which show that collisions which produce particles and radiation may be very important during the formation of a compact radio component. The consequences of electron-positron production, bremsstrahlung and proton-proton inelastic collisions ultimately giving rise to neutrinos and gamma rays for the development and energetics of the radio component are then examined, and upper limits to the amount of energy which can be channeled into radio components from an active region without giving rise to a high-energy X-ray source are derived.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 245
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Neutrino, gamma-ray, electron, and positron production in an ultrarelativistic plasma (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Neutrino, gamma-ray, electron and positron production resulting from inelastic proton-proton collisions in a highly relativistic plasma such as may exist in extragalactic radio or gamma-ray burst sources is examined. The source functions of primary (pions, kaons, and neutrons) and secondary (photons, electrons, positrons and neutrinos) products of relativistic nuclear collisions are computed for the cases of power law and Maxwellian relativistic proton distributions. It is shown that in plasma which is optically thin to interactions between the plasma and secondary gamma-rays, electrons and positrons, only a small fraction of the initial energy is emitted in the observable form of neutrinos and gamma rays. In an optically thick plasma on the other hand, most of the energy of the relativistic protons is found to be equally divided between gamma rays and neutrinos, although only the neutrinos may escape freely to be observed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
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  • 3
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    Superluminal motion in compact radio sources (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The observations of radio sources whose components appear to move superluminally are now sufficient to eliminate certain theoretical models. However, a number of models might be still relevant. The models which involve relativistic bulk motions of the radio components seem to provide the most likely explanation of apparent superluminal motion. A summary of observational predictions of various models for superluminal motions is included.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 92
    Format: text
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  • 4
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    The scattering of energetic particles by waves in a finite beta plasma (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Solutions are presented for the dispersion relation of waves propagating parallel to the ambient magnetic field, in a plasma having an arbitrary ratio of thermal to magnetic pressure, beta. Previous results applicable only to wave frequencies much lower than the ion cyclotron frequency are extended to include all frequencies lower than the electron cyclotron frequency. The cyclotron turnovers are found to occur at significantly lower frequencies in finite beta plasmas. Cyclotron damping is significant for small wavelength waves. These results show that in energetic particle scattering by electromagnetic turbulence in a plasma with beta value greater than 40, scattering by waves with wave frequencies greater than the ion cyclotron frequency can be neglected. This condition is satisfied in many astrophysical plasmas.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 334-338
    Format: text
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  • 5
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    Studies of X-ray clusters of galaxies/intergalactic plasmas (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Intergalactic plasmas were investigated from both an observational and theoretical point of view. A multiobject spectrometer, the MX spectrograph was used to obtain detailed dynamical information on clusters of galaxies; this information was then compared with X ray emission from hot gas in these clusters. Several spectra of galaxies are presented, and data reduction of the spectra was discussed. The existence of quasar winds in Seyfert galaxies and the interaction between such a wind and the interstellar medium also were considered.
    Keywords: ASTROPHYSICS
    Type: NASA-CR-173825 , NAS 1.26:173825
    Format: application/pdf
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  • 6
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    Velocity dispersions for X-ray-emitting clusters of galaxies (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Combining spectroscopy for five clusters of galaxies reported to contain X-ray sources with previously published data for 21 X-ray clusters, suggested correlations between the cluster's velocity dispersions and their X-ray properties have been tested. Unlike previous investigations, it is found that, for all reasonable data subsets, the cluster radial velocity dispersions sigma(r) are correlated with the cluster X-ray luminosities L/x/ at a confidence level exceeding 99%. The best-fit slope of the (log sigma/r/, log L/x/)-relation is somewhat larger than theoretically predicted, but accurate determination of that relation requires further X-ray and optical observations. For the 'most reliable' data subsample a correlation between sigma(r) and the X-ray source temperatures is also found but at a much lower confidence level (85%) than derived by previous investigators from smaller samples.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 232
    Format: text
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  • 7
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    The heating of gas in clusters of galaxies by relativistic electrons - Collective effects (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: We show that the rate at which gas is heated in X-ray clusters of galaxies by streaming relativistic electrons can be much greater than the Coulomb heating rate because of the stimulated growth of a high level of electrostatic turbulence and its subsequent collapse to shorter wavelengths. This enhanced heating (and, hence, energy loss) rate allows the X-ray emitting gas to be heated by those particles which are observable through their synchrotron emission at low radio frequencies and yields a radio source size consistent with the observed radio halo sizes in the Coma cluster. The heating of gas in clusters of galaxies by relativistic electrons will significantly affect the cluster gas dynamics.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
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