1,760 research outputs found

    An X-ray red-shift test for clusters of galaxies up to Z greater than or equal to 1

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    Correlated measurements of red-shifted iron line emission and apparent surface brightness are suggested for unambiguously defining intrinsic X-ray characteristics for clusters of galaxies up to z greater than or equal to 1. If some of the weak unidentified high galactic latitude X-ray sources are clusters at z approximately 1-3, then such correlated measurements should be feasible witin the complement of instruments aboard the HEAO-B orbiting X-ray telescope observatory. In addition, those clusters at z less than 1 would require spectral data from broader bandwidth experiments, such as the all-sky survey to be provided by the proportional counters aboard the first mission of the High Energy Astronomy Observatory (HEAO-A)

    ON THE MEASUREMENT OF A COSMOLOGICAL DIPOLE IN THE PHOTON NUMBER COUNTS OF GAMMA-RAY BURSTS

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    If gamma-ray bursts are cosmological or in a halo distribution their properties are expected to be isotropic (at least to 1st order). However, our motion with respect to the burst parent population (whose proper frame is expected to be that of the Cosmic Microwave Background (CMB), or that of a static halo) will cause a dipole effect in the distribution of bursts and in their photon number counts (together termed a Compton-Getting effect). We argue that the photon number count information is necessary to distinguish a genuine Compton-Getting effect from some other anisotropy and to fully test the proper frame isotropy of the bursts. Using the 2B burst catalogue and the dipole determined from the CMB, we find the surprising result that although the number weighted distribution is consistent with isotropy, the fluence weighted dipole has a correlation with the CMB dipole that has a probability of occuring only 10% of the time for an isotropic photon distribution. Furthermore, the photon and number dipoles are inconsistent under the hypothesis of isotropy, at the 2-sigma level. This could be an indication that a non-negligible fraction of gamma-ray bursts originate in the local, anisotropic universe. (shortened Abstract)Comment: Accepted by ApJ. Self-unpacking (use csh), uuencoded, compressed Postscript, 16 pages + 4 Figures (5 files

    The diffuse component of the cosmic X-radiation

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    The A-2 experiment on HEAO-1 is specifically developed to study the diffuse radiation of the entire X-ray sky over a wide bandwidth, covering both the soft X-ray emission from nearby regions of the galaxy and the isotropic hard X-radiation indicative of remote extragalactic origins. A partial conclusion from the experiment is that a hot thermal plasma, on a scale comparable to that of the universe, may be the principal source of hard X-radiation characteristic of the extragalactic sky. Some key features of this background were defined

    K-alpha X-rays from cosmic ray oxygen

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    Equilibrium charge fractions are calculated for subrelativistic cosmic ray oxygen ions in the interstellar medium. These are used to determine the expected flux of K-alpha rays arising from atomic processes for a number of different postulated interstellar oxygen spectra. Relating these results to the diffuse X-ray background measured at the appropriate energy level suggests an observable line feature. If the flux of low energy cosmic ray oxygen is sufficiently large, K-alpha X-ray line emission from these nuclei will comprise a significant fraction of the total diffuse flux at approximately 0.6 keV. A satellite borne detector with a resolution greater than 30 percent could observe this feature if the subrelativistic interstellar cosmic ray oxygen spectrum is as large as certain theoretical estimates expressed in the text

    Historical Mechanisms: An Approach to Transfer Scientific Categories to History

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    Abstract—Historical Mechanisms allow rational analysis ofworld history under Unitarian views in its complexities anddialectical differences especially power structures and theirconflicts. Apparent specialties relate themselves, aftermodifications of space and time without losing anything of theirfascination. Following Goethe, the general exists out of manypeculiarities but within peculiarities is always the general.Exceptions can be explained easier. Historical Mechanismsrepresent the unity of world historical processes which usuallywould fall apart with the enormous chaos of details. Naturally aUnitarian and absolute formula for world history still cannot befound. But the categories and metaphors from the naturalsciences allow a better overview of historical processes. Detailedresearch is important as well, however, it needs to be locatedwithin world historical lines, and otherwise specific events cannotbe understood in their full extent. In the article severalmetaphors and pictures will be presented which only serve for abetter understanding of such processes and simplify them

    A limit to the X-ray luminosity of nearby normal galaxies

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    Emission is studied at luminosities lower than those for which individual discrete sources can be studied. It is shown that normal galaxies do not appear to provide the numerous low luminosity X-ray sources which could make up the 2-60 keV diffuse background. Indeed, upper limits suggest luminosities comparable with, or a little less than, that of the galaxy. This is consistent with the fact that the average optical luminosity of the sample galaxies within approximately 20 Mpc is slightly lower than that of the galaxy. An upper limit of approximately 1% of the diffuse background from such sources is derived

    Two-twenty Kev Spectrum of X-rays from the Crab Nebula and the Diffuse Background near Galactic Anticenter

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    X ray spectroscopy of Crab nebula and diffuse background by sounding balloons and rocket

    The Low Energy Spectrum of Cosmic Rays as an Indicator of Primary Source Characteristics and Interstellar Propagation

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    Low energy spectrum of cosmic rays as indicator of primary source characteristics and interstellar propagatio

    Iron line emission from X-ray sources

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    Iron line emission from X ray source
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