Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Institution
- Publication
- Publication Type
Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Effects Of Mass And Distance Uncertainties On Calculations Of Flux From Giant Molecular Clouds, Matt Coel
Effects Of Mass And Distance Uncertainties On Calculations Of Flux From Giant Molecular Clouds, Matt Coel
Dissertations, Master's Theses and Master's Reports
It is assumed that the distribution of the Milky Way cosmic rays, the cosmic ray ‘sea,’ is even throughout the Galaxy. This assumption can be tested by measuring gamma rays produced from cosmic ray interactions with Giant Molecular Clouds. The gamma ray flux depends on the mass and distance of a given molecular cloud as well as the cosmic ray flux in its vicinity. Thus a predicted gamma ray flux can be compared to actual flux data from a detector. Uncertainties from measuring the mass of and distance to the clouds are taken into account for this prediction. This report …
Supernova Remnants And Cosmic Ray Acceleration Mechanisms, Ariel L. Simons, Yasunobu Uchiyama
Supernova Remnants And Cosmic Ray Acceleration Mechanisms, Ariel L. Simons, Yasunobu Uchiyama
STAR Program Research Presentations
Supernova remnants (SNRs) are considered to be the primary energy source of galactic-origin cosmic rays. Within this prediction exist two models, leptonic and hadronic, to explain the acceleration of charged particles up to a PeV in energy. Using data from the Fermi Gamma-ray Space Telescope (FGST) each model is expected to produce a distinct spectral energy distribution (SED) over a photon energy range of 100MeV to 100GeV. This analysis is focused on the methods for generating SEDs for the SNR Cassiopeia A and how they can be used to constrain the likelihood of either acceleration model.
Observations Of Very High Energy Gamma-Ray Emission From Supernova Remnants With Veritas, Mark Theiling
Observations Of Very High Energy Gamma-Ray Emission From Supernova Remnants With Veritas, Mark Theiling
All Dissertations
The nature and source of cosmic rays has been at the core of particle astrophysics since their discovery almost a century ago. The cosmic ray spectrum is best described by a broken power law, and can be better understood as three distinct parts. Theory holds that cosmic rays up to ∼1015 eV – those below the “knee” or steepening in the spectrum – are produced in the shocks of supernova remnants. Direct detection of cosmic rays produced in supernova remnant shocks is impossible, however, as cosmic rays below ∼1018 eV are deflected by the Galactic magnetic field and cannot be …
A Cosmic Ray Current-Driven Instability In Partially Ionised Media, Brian Reville, John Kirk, Peter Duffy, Stephen O'Sullivan
A Cosmic Ray Current-Driven Instability In Partially Ionised Media, Brian Reville, John Kirk, Peter Duffy, Stephen O'Sullivan
Articles
We investigate the growth of hydromagnetic waves driven by streaming cosmic rays in the precursor environment of a supernova remnant shock. It is known that transverse waves propagating parallel to the mean magnetic field are unstable to anisotropies in the cosmic ray distribution, and may provide a mechanism to substantially amplify the ambient magnetic field. We quantify the extent to which temperature and ionisation fractions modify this picture. Using a kinetic description of the plasma we derive the dispersion relation for a collisionless thermal plasma with a streaming cosmic ray current. Fluid equations are then used to discuss the effects …
Cosmic Ray Diurnal Anisotropy Related To Solar Activity, Rajesh K. Mishra, Rekha Agarwal Mishra
Cosmic Ray Diurnal Anisotropy Related To Solar Activity, Rajesh K. Mishra, Rekha Agarwal Mishra
Turkish Journal of Physics
The occurrence of a large number high amplitude event (HAE) of cosmic ray diurnal anisotropy during 1981--1994 has been examined as a function of solar activity. The high amplitude days with the time of maximum in the corotational/azimuthal direction do not indicate any significant correlation with solar activity. Our observations suggest that the direction of the anisotropy of HAE events contribute significantly to the long-term behaviour of the diurnal anisotropy. The occurrence of HAE is dominant during sunspot maximum as well as sunspot minimum.
Influence Of Solar Activity On Low Amplitude Cosmic Ray Diurnal Anisotropy, Rajesh K. Mishra, Rekha Agarwal Mishra
Influence Of Solar Activity On Low Amplitude Cosmic Ray Diurnal Anisotropy, Rajesh K. Mishra, Rekha Agarwal Mishra
Turkish Journal of Physics
A detailed study has been conducted on the occurrence of a large number of low amplitude events (LAE) of cosmic ray (CR) diurnal anisotropy during 1981--1994 as a function of solar activity. The low amplitude days with the time of maximum in the corotational/azimuthal direction do not indicate any significant correlation with solar activity. Our observations suggest that the direction of the anisotropy of LAE events contribute significantly to the long-term behaviour of the CR diurnal anisotropy. The occurrence of LAE is dominant during solar activity minimum years.
Features Of Daily Variation In Cosmic Ray Intensity During High/Low Amplitude Events, Rajesh K. Mishra, Rekha Agarwal Mishra
Features Of Daily Variation In Cosmic Ray Intensity During High/Low Amplitude Events, Rajesh K. Mishra, Rekha Agarwal Mishra
Turkish Journal of Physics
A detailed study has been conducted on the long-term changes in the diurnal, semi-diurnal and tri-diurnal anisotropy of cosmic rays in terms of the high/low amplitude anisotropic wave train events (HAE/LAE) during the period 1981--94 using the neutron monitor data from the Deep River neutron monitoring station. In all, 38 HAE and 28 LAE cases have been studied. An inter-comparison of the first three harmonics during these events has been made so as to understand the basic reason causing the occurrence of these types of events. It has been observed that the phase of diurnal anisotropy shifts towards earlier hours …
Large Amplitude Wave Trains In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra
Large Amplitude Wave Trains In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra
Turkish Journal of Physics
Using ground-based neutron monitor data of Deep River, the high amplitude anisotropic wave train events (HAE) in cosmic ray intensity have been investigated during the period 1991--1994. It has been observed that the phase of diurnal anisotropy for majority of HAE cases remains in the same co-rotational direction, whereas for some HAE cases the phase of diurnal anisotropy has shifted to later hours. For the majority of HAE cases the amplitude of semi-diurnal anisotropy remains statistically the same, whereas the phase of semi-diurnal anisotropy for all HAE cases has shifted to later hours. Furthermore, for tri-diurnal anisotropy the phase shifts …
Exceptionaly Low Amplitude Anisotropic Wave Train Events In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra
Exceptionaly Low Amplitude Anisotropic Wave Train Events In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra
Turkish Journal of Physics
The unusually low amplitude anisotropic wave train events (LAEs) in cosmic ray intensity using the ground-based Deep River neutron monitor data has been studied during the period 1991--94. It has been observed that the phase of the diurnal anisotropy for majority of the LAE events remains in the corotational direction. However, for some of the LAE events the phase of the diurnal anisotropy shifts towards earlier hours. On the other hand, the amplitude of the semi-diurnal anisotropy remains statistically the same whereas, phase shift towards later hours; similar trend has also been found in case of tri-diurnal anisotropy. The interplanetary …