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  • ASTROPHYSICS  (4)
  • ASTRONOMY  (1)
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  • 1
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    Secondary production of neutral pi-mesons and the diffuse galactic gamma radiation (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Isobaric and scaling model predictions of the secondary spectra of neutral pi-mesons produced in proton-proton collisions, at energies between threshold and a few GeV, are compared on the basis of accelerator data and found to show the isobaric model to be superior. This model is accordingly used, in conjuction with a scaling model representation at high energies, in a recalculation of the pi exp (0) gamma-radiation's contribution to the diffuse galactic gamma background; the cosmic ray-induced production of photons (whose energy exceeds 100 MeV) by such radiation occurs at a rate of 1.53 x 10 to the -25 photons/(s-H atom). These results are compared with previous calculations of this process as well as with COS-B observations of the diffuse galactic gamma-radiation.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 157; 2, Ma
    Format: text
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  • 2
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    Time-dependent behavior of active galactic nuclei with pair production (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: We study the properties of coupled partial differential equations describing the time-dependent behavior of the photon and electron occupation numbers for conditions likely to be found near active galactic nuclei (AGN). The processes governing electron acceleration are modeled by a stochastic accelerator, and we include acceleration by Alfvenic and whistler turbulence. The acceleration of electrons is limited by Compton and synchrotron losses, and the number density of electrons depends on pair production and annihilation processes. We also treat particle escape from the system. We examine the steady, (possibly) oscillatory, and unstable solutions that arise for various choices of parameters. We examine instabilities related to pair production and trapping and consider the formation of pair jets.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on Physics of Accretion Disks Around Compact and Young Stars; p 2
    Format: application/pdf
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  • 3
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    The production spectrum of a relativistic Maxwell-Boltzmann gas (1984)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A formula is derived for use in the calculation of the spectrum of particles or photons produced through particle collisions in a Maxwell-Boltzmann gas. The result is valid for all temperatures and for the general case when the gas contains different mass particles. It is written in terms of a double integral over the cross section differential in the energy of the produced particles (or photons) in the center-of-momentum system of two colliding particles. Analytic expressions for the reaction rate and luminosity are also derived and reproduce the findings of previous work. Application to the problem of the annihilation spectrum from a relativistic Maxwell-Boltzmann electron-positron gas is made. Agreement is found between the present work and previous numerical and analytical studies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 328-333
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  • 4
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    OSSE observations of 3C 273 (1995)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: We report results of multiple observations of the quasar 3C 273 with the Oriented Scintillation Spectrometer Experiment (OSSE) instrument on the Compton Gamma Ray Observatory. These observations span the period from 1991 June through 1993 January and represent the most sensitive observations to date in low-energy gamma rays. The source was detected at historically weak 100 keV fluxes compared with previous measurements. Variability by factors of approximately 3 on timescales of approximately equal 2 months was observed in the energy band 50-150 keV. The data are well described by a single power law with a proton number index Gamma = 1.7 +/- 0.1. No significant change of Gamma was observed during changes in intensity. Thermal models do not provide acceptable fits to the data. When the OSSE data are combined with contemporaneous measurements by COMPTEL and EGRET, the spectrum is seen to break at an energy of 1.0(+0.9, -0.4) MeV to a softer power law with Delta Gamma = 0.7(+0.06, -0.11), forming a power law with Gamma = 2.4 between approximately 1 MeV and several GeV.
    Keywords: ASTRONOMY
    Type: The Astrophysical Journal, Part 1 (ISSN 0004-637X); 445; 1; p. 182-188
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  • 5
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    Binary collision rates of relativistic thermal plasmas. II - Spectra (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Spectra of importance for the analysis of relativistic thermal plasmas are numerically calculated assuming a thermal form for the particle distribution functions. Complete sets of optically thin thermal electron-proton, electron-electron, and electron-positron bremsstrahlung spectra are calculated throughout the transrelativistic regime of electron temperatures and compared with approximate expressions for the spectra in the nonrelativistic and extreme relativistic regimes of temperature. A method for calculating accurate secondary particle production spectra in proton-proton collisions from threshold to the highest energies is presented based on an isobaric model near threshold and scaling representations at high energies. The production spectra of charged and neutral pions resulting from proton-proton collisions in relativistic proton plasmas are calculated, and the resultant electron, positron, and gamma-ray spectra from the decay of secondary pions are presented.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 307; 47-59
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