4,773 research outputs found

    Is there a 1998bw-like supernova in the afterglow of gamma ray burst 011121?

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    We use the very simple and successful Cannonball Model (CB) of gamma ray bursts (GRBs) and their afterglows (AGs) to analyze the observations of the strongly extinct optical AG of the relatively nearby GRB 011121, which were made with ground-based telescopes at early times, and with the HST at later time. We show that GRB 011121 was indeed associated with a 1998bw-like supernova at the GRB's redshift, as we had specifically predicted for this GRB before the supernova could be observed.Comment: Submitted for publicatio

    The threat to life from Eta Carinae and gamma ray bursts

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    Eta Carinae, the most massive and luminous star known in our galaxy, is rapidly boiling matter off its surface. At any time its core could collapse into a black hole, which may result in a gamma-ray burst (GRB) that can devastate life on Earth. Auspiciously, recent observations indicate that the GRBs are narrowly beamed in cones along the rotational axis of the progenitor star. In the case of Eta Carinae the GRBs will not point to us, but will be ravaging to life on planets in our galaxy that happen to lie within the two beaming cones. The mean rate of massive life extinctions by jets from GRBs, per life-supporting planet in galaxies like ours, is once in 100 million years, comparable to the rate of major extinctions observed in the geological records of our planet.Comment: Published in Astrophysics and Gamma Ray Physics in Space (eds. A. Morselli and P. Picozza), Frascati Physics Series Vol. XXIV (2002), pp. 513-52

    Is the diffuse gamma background radiation generated by galactic cosmic rays?

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    We explore the possibility that the diffuse gamma-ray background radiation (GBR) at high galactic latitudes could be dominated by inverse Compton scattering of cosmic ray (CR) electrons on the cosmic microwave background radiation and on starlight from our own galaxy. Assuming that the mechanisms accelerating galactic CR hadrons and electrons are the same, we derive simple and successful relations between the spectral indices of the GBR above a few MeV, and of the CR electrons and CR nuclei above a few GeV. We reproduce the observed intensity and angular dependence of the GBR, in directions away from the galactic disk and centre, without recourse to hypothetical extragalactic sources.Comment: Submitted for publicatio

    Nature of Philosophy

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    The aim of this paper is to examine the nature, scope and importance of philosophy in the light of its relation to other disciplines. This work pays its focus on the various fundamental problems of philosophy, relating to Ethics, Metaphysics, Epistemology Logic, and its association with scientific realism. It will also highlight the various facets of these problems and the role of philosophers to point out the various issues relating to human issues. It is widely agreed that philosophy as a multi-dimensional subject that shows affinity to others branches of philosophy like, Philosophy of Science, Humanities, Physics and Mathematics, but this paper also seeks, a philosophical nature towards the universal problems of nature. It evaluates the contribution and sacrifices of the great sages of philosophers to promote the clarity and progress in the field of philosophy

    The Cannonball Model of Gamma Ray Bursts: Lines in the X-Ray Afterglow

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    Recent observations suggest that gamma-ray bursts (GRBs) and their afterglows are produced by jets of highly relativistic cannonballs (CBs), emitted in supernova explosions. The fully ionized CBs cool to a temperature below 4500 K within a day or two, at which point electron-proton recombination produces an intense Lyman-α\alpha emission. The line energy is Doppler-shifted by the CBs' motion to X-ray energies in the observer's frame. The measured line energies, corrected for their cosmological redshift, imply Doppler factors in the range 600 to 1000, consistent with those estimated -in the CB model- from the characteristics of the γ\gamma-ray bursts. All other observed properties of the lines are also well described by the CB model. Scattering and self-absorption of the recombination lines within the CB also produce a wide-band flare-up in the GRB afterglow, as the observations indicate. A very specific prediction of the CB model is that the X-ray lines ought to be narrow and move towards lower line energies as they are observed: their current apparently large widths would be the effect of time integration, and/or of the blending of lines from CBs with different Doppler factors.Comment: 8 pages, no figure

    The vicissitudes of "cannonballs": a response to criticisms by A.M. Hillas and a brief review of our claims

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    A.M. Hillas, in a review of the origins of cosmic rays, has recently criticized the "cannonball" (CB) model of cosmic rays and gamma-ray bursts. We respond to this critique and take the occasion to discuss the crucial question of particle acceleration in the CB model and in the generally accepted models. We also summarize our claims concerning the CB model.Comment: 3.3 pages, no figure

    A (p, ν)-extension of the Appell function F1(·) and its properties

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    In this paper, we obtain a (p, v)-extension of the Appell hypergeometric functionF1(·), together with its integral representation, by using the extended Beta functionBp,v(x, y) introduced in [9]. Also, we give some of its main properties, namely theMellin transform, a differential formula, recursion formulas and a bounded inequality. In addition, some new integral representations of the extended Appell functionF1,p,v(·) involving Meijer’s G-function are obtained
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