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  • 1
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    Predictions of extragalactic gamma ray fluxes between 1 and 100 Mev. (1969)
    In:  Other Sources
    Details
    Publication Date: 2011-08-12
    Description: Extragalactic gamma ray fluxes predicted, discussing collisions, matter-antimatter annihilation and cosmological implications
    Keywords: SPACE RADIATION
    Type: ; ADEMIE DES SCIENCES
    Format: text
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  • 2
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    Ionising flux of cosmic background radiation (1976)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The indirect method of estimating the diffuse metagalactic flux of ionizing radiation proposed by Sunyaev (1969) is reconsidered in the light of further studies of the interaction of this radiation with galactic gas. An upper limit is derived for the intensity of the metagalactic background radiation to which the neutral interstellar medium is exposed. This limit on the ionizing radiation flux severely restricts the emission from a galactic corona containing gas in the temperature range 100,000 to 1,000,000 K. An upper limit of 10 to the 29.2 erg/sec/Hz is obtained for the mean luminosity radiated by a quasar in the energy band 40-170 eV. The 21-cm observations examined indicate that further than about 30 kpc from the center of the galaxy self-shielding by H II is possible only when the critical metagalactic ionizing flux is not exceeded.
    Keywords: SPACE RADIATION
    Type: Nature; 260; Apr. 8
    Format: text
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  • 3
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    The design and evaluation of grazing incidence relay optics (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: X-ray astronomy, both solar and celestial, has many needs for high spatial resolution observations which have to be performed with electronic detectors. If the resolution is not to be detector limited, plate scales in excess of 25 microns arc/sec, corresponding to focal lengths greater than 5 m, are required. In situations where the physical size is restricted, the problem can be solved by the use of grazing incidence relay optics. A system was developed which employs externally polished hyperboloid-hyperboloid surfaces to be used in conjunction with a Wolter-Schwarzschild primary. The secondary is located in front of the primary focus and provides a magnification of 4, while the system has a plate scale of 28 microns arc/sec and a length of 1.9 m. The design, tolerance specification, fabrication and performance at visible and X-ray wavelengths of this optical system are described.
    Keywords: OPTICS
    Type: Solar X-ray Astronomy Sounding Rocket Program; 6 p
    Format: application/pdf
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  • 4
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    High energy cosmic ray signature of quark nuggets (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: It has been recently proposed that dark matter in the Universe might consist of nuggets of quarks which populate the nuclear desert between nucleons and neutron star matter. It is further suggested that the Centauro events which could be the signature of particles with atomic mass A approx. 100 and energy E approx. 10 to 15th power eV might also be related to debris produced in the encounter of two neutron stars. A further consequence of the former proposal is examined, and it is shown that the production of relativistic quark nuggets is accompanied by a substantial flux of potentially observable high energy neutrinos.
    Keywords: SPACE RADIATION
    Type: HE-6.2-11 , 19th Intern. Cosmic Ray Conf - Vol. 8; p 290-293; NASA-CP-2376-VOL-8
    Format: application/pdf
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  • 5
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    Decay of long-lived particles in the early universe (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: It is pointed out that radiative decay of massive fermions can distort the cosmic background radiation. The present investigation is concerned with a study of decay lifetimes in the range from 10 to 100,000 years. Attention is given to the physics involved in determining the effect of radiative decay of massive fermions on observed photon backgrounds. The case of particles which decoupled when the effective number of species in equilibrium was in the range from 50 to 100 is considered, and constraints on particle masses and lifetimes are placed on the basis of observed photon fluxes. This approach provides results with special applications to particles predicted by supersymmetry theories and to right-handed neutrinos. Implications for galaxy formation are also discussed.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 269; June 1
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  • 6
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    Large-scale anisotropy of the cosmic microwave background radiation (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Inhomogeneities in the large-scale distribution of matter inevitably lead to the generation of large-scale anisotropy in the cosmic background radiation. The dipole, quadrupole, and higher order fluctuations expected in an Einstein-de Sitter cosmological model have been computed. The dipole and quadrupole anisotropies are comparable to the measured values, and impose important constraints on the allowable spectrum of large-scale matter density fluctuations. A significant dipole anisotropy is generated by the matter distribution on scales greater than approximately 100 Mpc. The large-scale anisotropy is insensitive to the ionization history of the universe since decoupling, and cannot easily be reconciled with a galaxy formation theory that is based on primordial adiabatic density fluctuations.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; vol. 244
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  • 7
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    Scale-invariant density perturbations, anisotropy of the cosmic microwave background, and large-scale peculiar velocity field (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The large-scale peculiar velocity field and the large- and intermediate-angular scale anisotropy of the cosmic microwave background are studied in inflationary cosmological models of critical density and containing primordial scale-invariant adiabatic density perturbations. Comparison with recent observations by de Vaucouleurs and Peters Provides tentative support for a cold dark matter scenario in which the dark matter is not appreciably less clustered than the luminous galaxy distribution.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 293; L1-L5
    Format: text
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  • 8
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    Fine-scale anisotropy of the cosmic microwave background in a universe dominated by cold dark matter (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The fine-scale anisotropy of the cosmic microwave background radiation has been studied in cosmological models with a scale-invariant primordial adiabatic density fluctuation spectrum dominated by cold, weakly interacting particles. Normalization of the present fluctuation spectrum to the observed galaxy distribution results in excessive temperature anisotropy when compared to a recent upper limit on 4.5 arcmin unless the density parameter exceeds 0.4. When this result is combined with the requirement that the universe be at least 13 billion years old, it is found that if the cosmological constant is zero, then the density parameter is between roughly 0.4 and 1 and the Hubble constant is between roughly 60 km/s/Mpc and 50 km/s/Mpc.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 285; L39-L43
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  • 9
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    On the distances to transient X-ray sources. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Estimation of the distance of three transient X-ray sources characterized by a rapid increase to a flux comparable with the strongest galactic X-ray sources, followed by a slower decay over a time scale of three to four months. A simple argument based only on X-ray data is presented, which yields a typical distance estimate on the order of a few kiloparsecs. In particular, it is demonstrated that it is most unlikely that the transient X-ray sources can be extragalactic in nature and produced by supernova events in nearby galaxies.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 181; May 1
    Format: text
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  • 10
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    Thermal-bremsstrahlung interpretation of cluster X-ray sources. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Analysis of the X-ray data for the extended sources in Coma, Perseus, and Virgo in terms of an isothermal gas-sphere model emitting thermal-bremsstrahlung radiation. It is found that the gas distribution is somewhat less centrally condensed than the galaxies, and that the gas mass is generally a small fraction of the binding mass of each cluster. In the case of the Coma cluster, approximately one-eighth of the binding mass (with an uncertainty of about 50%) may be in the form of hot gas at 100,000,000 K if H sub zero = 50 km/sec/Mpc.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 184; Sept. 15
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