4,773 research outputs found
Is there a 1998bw-like supernova in the afterglow of gamma ray burst 011121?
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
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?
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
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
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- 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 -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
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
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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