It has recently been suggested that neutron stars inside the shells of young supernova remnants (SNR) are the sources of PeV cosmic rays and that the interaction of the particles with the radiation ...field in the SNR causes electron pair production, which has relevance to recent observations of 'high' positron fluxes. Furthermore, the character of the interaction is such that the well-known knee in the cosmic ray energy spectrum can be explained. Our examination of the mechanism leads us to believe that the required parameters of SN and pulses are so uncommon that the knee and positron fraction can only be explained if a single, local and recent SN - and associated pulsar - are concerned.
A very recent observation by the Auger Observatory group claims strong evidence for cosmic rays above 56 EeV being protons from Active Galactic Nuclei. If, as would be expected, the particles above ...the ankle at about 2 EeV are almost all of extragalactic origin then it follows that the characteristics of the nuclear interactions of such particles would need to be very different from conventional expectation -- a result that follows from the measured positions of 'shower maximum' in the Auger' work. Our own analysis gives a different result, viz that the detected particles are still 'massive' specifically with a mean value of <ln A> = 2.2 +- 0.8. The need for a dramatic change in the nuclear physics disappears.
Neutrino astronomy - Introductory remarks Wolfendale, Arnold Whittaker
Philosophical transactions of the Royal Society of London. Series A: Physical sciences and engineering,
01/1994, Letnik:
346, Številka:
1678
Journal Article
Recenzirano
Nearly twenty years ago, G. D. Rochester and I organized a Discussion Meeting here on the origin of the cosmic radiation. P art of that meeting was devoted to primary gamma rays, and this meeting was ...followed a few years later by a meeting devoted entirely to gamma ray astronomy. At that time gamma rays represented a ‘new window on the Universe’. Now it is the turn of neutrinos to move into that slot, although it must be said that neutrino astronomy is not as far on as gamma ray astronomy was at that stage. Nevertheless, the subject has started and has already thrown up some dramatic questions, questions of interest to both astronomer and elementary particle physicist. In the more conventional astronomies, the Sun appears to be quite well behaved, and reasonably understood, with the interests of many centring on more distant and ‘dramatic’ objects, such as supernovae and extragalactic sources. With neutrinos, however, supernovae seem to be well behaved — at the superficial level, at least and based on one event — but the Sun does not. The remarkable deficit in solar neutrino flux recorded by Davis and collaborators over the past decades has been confirmed and we look forward to hearing the details of these confirmations, as well as the energy dependence of the flux and its comparison with expectation.
Global Warming—Some Perspectives Anatoly D. Erlykin; Arnold W. Wolfendale; Edward Hanna
Journal of environmental science and engineering. B,
04/2012, Letnik:
1, Številka:
4
Journal Article
J.Phys. G31 (2005) 255-264 We have argued J. Szabelski et al. (2002) that the well-known `ankle' in
the cosmic ray energy spectrum, at logE (eV) ~ 18.7-19.0, marks the transition
from mainly Galactic ...sources at lower energies to mainly extragalactic above.
Recently, however, there have been claims for lower transitional energies,
specifically from logE (eV) ~ 17.0 G. Thompson et al. (2004) via 17.2-17.8
V.S. Berezinsky et al. (2004) to 18.0 A.M. Hillas (2004). In our model the
ankle arises naturally from the sum of simple power law-spectra with slopes
differing by ~ 1.8; from differential slope -3.8 for Galactic particles (near
logE = 19) to ~ -2.0 for extragalactic sources. In the other models, on the
other hand, the ankle is intrinsic to the extragalactic component alone, and
arises from the shape of the rate of energy loss versus energy for the
(assumed) protons interacting with the cosmic microwave background (CMB).
Our detailed analysis of the world's data on the ultra-high energy spectrum
shows that taken together, or separately, the resulting mean sharpness of the
ankle (second difference of the log(intensity*E^3) with respect to logE) is
consistent with our `mixed' model. For explanation in terms of extragalactic
particles alone, however, the ankle will be at the wrong energy - for
reasonable production models and of insufficient magnitude if, as seems likely,
there is still a significant fraction of heavy nuclei at the ankle energy.
Mon.Not.Roy.Astron.Soc. 360 (2005) 236-252 A detailed search has been made for evidence of foreground contributions to
the Cosmic Microwave Background (CMB) WMAP, such foregrounds being related to
...our Galaxy. We find remarkable results. On the largest angular scales we find
significant differences between the power in the fluctuations for positive and
negative Galactic latitudes and between the four Galactic Quadrants. There are
also differences between the power spectrum at latitudes within 10 deg of the
Plane and at higher latitudes. The `slope' of the power spectrum has similar
variations.
In an effort to find the origin of these Galactic-style effects we have
examined the evidence from Galactic gamma rays, specifically from the EGRET
instrument. A correlation is found between gamma ray intensities and the CMB
and other cosmic ray indicators.
Most of the large scale Galactic asymmetries (eg north, south difference and
Quadrant variations) have analogues in cosmic ray asymmetries and also in some
other Galactic properties, such as the column density of gas. Thus, it is
possible to hypothesise on direct cosmic ray-induced contributions, although it
may be that cosmic rays are simply the indicators of Galactic `conditions'
which are influencing the residual CMB fluctuations.
Irrespective of the actual cause of the correlations we have endeavoured to
extrapolate to the situation where the residual foreground is minimised. The
effect on the usually-derived cosmological properties - universal matter
content, ionization, the tensor contribution, tilt and curvature - is briefly
examined.
It is often claimed that there should be a 'GZK cut-off" in the flux of
extragalactic cosmic rays, arising from interactions between the cosmic rays
and the cosmic micro-wave background photons (e.g. ...1 and 2). Some experiments
(3 and 4) show particles of even higher energy than this value and this has led
to claims for exotic processes (e.g. 5 and 6).
We contend that such claims are unnecessary - there is no predicted cut-off,
rather a continuation of the injection spectrum at reduced intensity. We have
combined the world's data and shown that the prediction for a rather flat
injection spectrum (exponent: 1.9 - 2.2) in the case of universal particle
injection provides a reasonable fit to the data. Conventional forms for the
particle attenuation in the intergalactic medium (e.g. 7 and 8) have been
assumed. Either protons or iron nuclei (or a mixture) will suffice.
Attention is drawn to another aspect, too, that of the losses on the
infra-red radiation which may be intense near to strong sources and for sources
in galaxy clusters. The attendant magnetic fields near the sources leads to
significantly long diffusion times through the strong infra-red fields. Two
'case histories' are considered.
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