arXiv subjects

A. D. Erlykin

Publications and source records attributed to A. D. Erlykin.

46 records · Page 3Linked to original sources

arXiv2004

Cosmic Rays and the Monogem Supernova Remnant

Recent findings indicate that the Monogem Ring supernova remnant (SNR) and the associated pulsar B0656+14 may be the 'Single Source' responsible for the knee in the cosmic ray (CR) energy spectrum at ~3 PeV. We estimate the contribution of this pulsar to CR in the PeV region. We conclude that although the pulsar can contribute to the formation of the knee, it cannot be the domimant source and a SNR is still needed. We also examine the possibility of the pulsar giving the peak of the extensive air shower (EAS) intensity observed from the region inside the Monogem Ring. If the experimental EAS results concerning a narrow source are confirmed, they can be important, since they give evidence: (i) for the acceleration of protons and heavier nuclei by the pulsar; (ii) for the existence of the confinement mechanism in SNR; (iii) that CR produced by the Monogem Ring SNR and associated pulsar B0656+14 were released recently giving rise to the formation of the knee and the observed narrow peak in the EAS intensity; (iv) for the Monogem Ring and the associated pulsar B0656+14 being identified as the Single Source proposed in our Single Source Model of the knee. A number of predictions of the examined scenario are made.

astro-ph↗

arXiv2003

High-energy cosmic gamma rays from the `Single Source'

Some six years ago, we (Erlykin and Wolfendale, 1997) proposed the `single source model' in which a local, recent supernova remnant (SNR) was responsible for the `knee' in the cosmic ray (CR) energy spectrum at ~3PeV. Stimulated by the paper by Bhadra (2002), which drew attention to a possible gamma ray signature of this local remnant, we now study the situation for the local source and we conclude that, in contrast to Bhadra's conclusion, the non-observation of this remnant is understandable - at least using our SNR model. It is due to the fact that this SNR, being local, develops in the local hot interstellar medium (HISM) with its low density of gas and also being nearby it will be an extended source occupying up to 40$^\circ$ of the sky and thus indistinguishable from the background.

astro-ph↗

arXiv2003

The visibility of shell-type supernova remnants in gamma rays

The idea that the shocks from supernova remnants (SNR) expanding into the interstellar medium (ISM) accelerate CR is still popular one but a number of authors have drawn attention to the fact that the experimental evidence for the presence of gamma rays from the expected interaction of CR with gas in the remnant is poor. Indeed, it is claimed that many SNR are not `seen' in GeV or TeV gamma rays, whereas `they should have been'. We have looked at this problem and we conclude that the idea of CR production in SNR cannot be faulted in this way, if the evacuation of ambient gas by the stellar wind of the progenitor star and, frequently, by associated earlier close-by SN, is taken into account; such phenomena are expected for the important Type II SN which result from very massive stars. Other SNR have, apparently, been seen and the interaction of SNR-accelerated particles with adjacent molecular clouds has been deemed responsible. However, we worry about this interpretation because of the slow progress of the SNR shock through such clouds, although electron-effects may, indeed, contribute. This paper is devoted mainly to the visibility of nearby SNR in gamma rays although many of the arguments also relate to remote SNR. For the nearby SNR another problem enters the scene: the large angular spread of the remnant. It is especially important for the old SNR, where cosmic rays have already diffused to a large distance from the SNR center. We have also examined the effect of the 'anomalous diffusion' of CR propagation in the non-homogeneous interstellar medium on the visibility of SNR for gamma rays of different energies.

astro-ph↗

arXiv2002

Spectral Features and Masses in the PeV Region

An analysis is made of the masses and spectral features for cosmic rays in the PeV region, insofar as they have a bearing on the problem of the interaction of cosmic ray particles. In our Single Source Model we identified two 'peaks' seen in a summary of the world's data on primary spectra, and claimed that they are probably due to oxygen and iron nuclei from a local, recent supernova. In the present work we examine other possible mass assignments. We conclude that of the other possibilities only Helium and Oxygen (instead of O and Fe) has much chance of success; the original suggestion is still preferred, however. Concerning our location with respect to the SNR shell, the analysis suggests that we are close to it - probably just inside.

astro-ph↗

arXiv2002

How Should We Modify the High Energy Interaction Models ?

An analysis has been made of the present situation with respect to the high energy hadron-nucleus and nucleus-nucleus interaction models as applied to cosmic rays. As is already known, there are inconsistencies in the interpretation of experimental data on the primary mass composition, which appear when different EAS components are used for the analyses, even for the same experiment. In the absence of obvious experimental defects, there is a clear need for an improvement to the existing models; we argue that the most promising way is to enlist two effects which should be present in nucleus- nucleus collisions but have not been allowed for before. These are: a few percent energy transfer into the EAS electromagnetic component due to electron- positron pair production or electromagnetic radiation of the quark-gluon plasma and a small slow-down of the cascading process in its initial stages associated with the extended lifetime of excited nuclear fragments. The latter process displaces the shower maximum deeper into the atmosphere.

hep-ph↗

arXiv2002

Properties of the Interstellar Medium and the Propagation of Cosmic Rays in the Galaxy

The problem of the origin of cosmic rays in the shocks produced by supernova explosions at energies below the so called 'knee' (at ~3*10$^6$ GeV) in the energy spectrum is addressed, with special attention to the propagation of the particles through the inhomogenious interstellar medium and the need to explain recent anisotropy results, [1]. It is shown that the fractal character of the matter density and magnetic field distribution leads to the likelihood of a substantial increase of spatial fluctuations in the cosmic ray energy spectra. While the spatial distribution of cosmic rays in the vicinity of their sources (eg. inside the Galactic disk) does not depend much on the character of propagation and is largely determined by the distribution of their sources, the distribution at large distances from the Galactic disk depends strongly on the character of the propagation. In particular, the fractal character of the ISM leads to what is known as 'anomalous diffusion' and such diffusion helps us to understand the formation of Cosmic Ray Halo. Anomalous diffusion allows an explanation of the recent important result from the Chacaltaya extensive air shower experiment [1], viz. a Galactic Plane Enhancement of cosmic ray intensity in the Outer Galaxy, which is otherwise absent for the case of the so-called 'normal' diffusion. All these effects are for just one reason: anomalous diffusion emphasizes the role of local phenomena in the formation of cosmic ray characteristics in our Galaxy and elsewhere.

astro-ph↗

arXiv2001

Properties of Cosmic Ray Interactions at PeV Energies

An analysis has been made of the present situation with the high energy hadron-nucleus and nucleus-nucleus interaction models. As is already known there are inconsistencies in the interpretation of experimental data on the primary mass composition, which appear when different EAS components are used for the analyses, even for the same experiment. In the absence of obvious experimental defects, there is a clear need for an improvement to the existing models; we argue that the most promising way is to introduce two effects which should be present in nucleus-nucleus collisions and have not been allowed for before. These are: a few percent energy transfer into the EAS electromagnetic component due to electron-positron pair production or electromagnetic radiation of quark-gluon plasma and a small slow-down of the cascading process in its initial stages associated with the extended lifetime of excited nuclear fragments. The latter process displaces the shower maximum deeper into the atmosphere.

astro-ph↗

arXiv2001

The Origin of the Knee in the Cosmic-Ray Energy Spectrum

A sudden steepening of the cosmic-ray energy spectrum (the knee) is observed at an energy of about 3 PeV (1 PeV = 10$^{15}$eV). The recent results on extensive air showers allow us to conclude that: a) the knee has an astrophysical origin; b) the 'sharpness' and the fine structure of the knee rule out 'Galactic Modulation' as the origin of the knee; c) most likely the knee is the result of the explosion of a single, recent, nearby supernova.

astro-ph↗

arXiv2000

Models for the Origin of the Knee in the Cosmic-Ray Spectrum

A sudden steepening of the cosmic-ray energy spectrum (the knee) is observed at an energy of about 3 PeV (1 PeV = $10^{15}$ eV). The experimental study of the PeV cosmic rays has intensified greatly during the last 3 years. The recent results on extensive air showers allow us to conclude that: a) the knee has an astrophysical origin; b) the `sharpness' and the fine structure of the knee rule out `Galactic Modulation' as the origin of the knee; c) most likely the knee is the result of the explosion of a single, recent, nearby supernova.

astro-ph↗

arXiv2000

Fine Structure in the Energy Spectrum of Cosmic Ray Protons at 50 GeV ?

The recently published precise spectrum of cosmic ray protons from the Alpha Magnetic Spectrometer has been examined in some detail from the standpoint of a search for deviations from a smooth, simple, power law. We find a significant excess ($\simeq$ 10% over $\sim$ 0.3 interval in logE) centered on 50 GeV in the published data. It is possible that the 'unfolding technique' adopted by the experimenters causes an overestimate of the excess but it is difficult to reduce it much below about (5 $\pm$ 3)%. We have examined other recent data, too. There is also evidence here, for an excess in the same energy region, although of only (1.6 $\pm$ 0.9)%. A value of (3 $\pm$ 1.5)% would be consistent with all the data. There are hints of similar excesses for heavier nuclei and electrons. Possible explanations are put forward for an excess, should it prove to be genuine.

astro-ph↗