Radio emission, cosmic ray electrons, and the production of gamma-rays in the Galaxy

1980 ◽  
Vol 236 ◽  
pp. 448 ◽  
Author(s):  
W. R. Webber ◽  
G. A. Simpson ◽  
H. V. Cane
Keyword(s):  
Radio Emission ◽  
Gamma Rays ◽  
Cosmic Ray ◽  
The Galaxy

scholarly journals What do Gamma Rays tell us about the ISM?: New Insight from the Compton Observatory

1996 ◽  
Vol 169 ◽  
pp. 437-446 ◽  
Author(s):  
Hans Bloemen
Keyword(s):  
Interstellar Medium ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Line Emission ◽  
Cosmic Ray ◽  
Gamma Ray Astronomy ◽  
Early Results ◽  
The Galaxy ◽  
Γ Ray ◽  
Insight Into

Gamma-ray astronomy has become a rich field of research and matured significantly since the launch of NASA's Compton Gamma Ray Observatory in April 1991. Studies of the diffuse γ-ray emission of the Galaxy can now be performed in far more detail and extended into the MeV regime, including both continuum and line emission. These studies provide unique insight into various aspects of the interstellar medium, in particular of the cosmic-ray component. This paper gives a brief review on the diffuse Galactic γ-ray emission and summarizes early results and prospects from the Compton Observatory.

scholarly journals Radio haloes around galaxies and in clusters

1978 ◽  
Vol 79 ◽  
pp. 161-163
Author(s):  
V. L. Ginzburg
Keyword(s):  
Cosmic Rays ◽  
Radio Emission ◽  
Cosmic Ray ◽  
Relativistic Electrons ◽  
Radio Halo ◽  
Normal Galaxies ◽  
Extended Region ◽  
The Galaxy ◽  
Nuclear Component ◽  
Galactic Sources

The question of whether or not our and other normal galaxies have some sort of halo - an extended region containing, in particular, cosmic rays - has been discussed for no less than 25 years. Such a “cosmic ray halo” (CRH) appears as a radio-halo, although the absence of the latter is not evidence against the presence of CRH. the point is that the relativistic electrons responsible for the radio emission from the radio-halo undergo synchrotron and Compton losses which are practically absent in the case of the cosmic-ray proton-nuclear component. Possibly because the discussion concerning the existence of the radio-halo in the Galaxy has lasted for years it has acquired a particular character. the latter is clearly reflected in the report by Baldwin (1976) who emphasized that: ȜIn this discussion so far I have avoided the use of the phrase Ȝradio-haloȝ. It arouses antagonism in otherwise placid astronomers and many sought to deny its existence …ȝ Such a situation evidently reflects the difficulties that arise in detecting the radio-halo of our own Galaxy when account is taken of other confusing galactic sources as well as of the metagalactic background.

Erratum: Cosmic-ray nuclei, antiprotons and gamma-rays in the galaxy: a new diffusion model

2016 ◽  
Vol 2016 (04) ◽  
pp. E01-E01 ◽  
Author(s):  
Carmelo Evoli ◽  
Daniele Gaggero ◽  
Dario Grasso ◽  
Luca Maccione
Keyword(s):  
Diffusion Model ◽  
Gamma Rays ◽  
Cosmic Ray ◽  
The Galaxy

scholarly journals Gamma Rays from Cosmic Rays

1981 ◽  
Vol 94 ◽  
pp. 309-319 ◽  
Author(s):  
A. W. Wolfendale
Keyword(s):  
Cosmic Rays ◽  
Gamma Rays ◽  
Molecular Clouds ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Cosmic Ray Interactions ◽  
The Galaxy ◽  
Γ Rays ◽  
Γ Ray

It is shown that there is evidence favouring molecular clouds being sources of γ-rays, the fluxes being consistent with expectation for ambient cosmic rays interacting with the gas in the clouds for the clouds considered. An estimate is made of the fraction of the apparently diffuse γ-ray flux which comes from cosmic ray interactions in the I.S.M. as distinct from unresolved discrete sources. Finally, an examination is made of the possibility of gradients of cosmic ray intensity in the Galaxy.

scholarly journals Cosmic ray nuclei, antiprotons and gamma rays in the galaxy: a new diffusion model

2008 ◽  
Vol 2008 (10) ◽  
pp. 018 ◽  
Author(s):  
Carmelo Evoli ◽  
Daniele Gaggero ◽  
Dario Grasso ◽  
Luca Maccione
Keyword(s):  
Diffusion Model ◽  
Gamma Rays ◽  
Cosmic Ray ◽  
The Galaxy

Gamma-rays from cosmic-ray irradiated molecular clouds

1981 ◽  
Vol 301 (1462) ◽  
pp. 533-535 ◽  
Keyword(s):  
Monte Carlo ◽  
Cosmic Rays ◽  
Gamma Rays ◽  
Molecular Clouds ◽  
Cosmic Ray ◽  
Monte Carlo Analysis ◽  
The Galaxy

An examination is made of the contribution to the number of apparently discrete sources of y-rays from cosmic rays interacting with molecular clouds in the Galaxy. Attention is directed to specific nearby clouds and to clouds in general, the latter by a Monte-Carlo analysis.

scholarly journals On the Relationship Between Recent Measurements of Cosmic Ray Electrons, Nonthermal Radio Emission from the Galaxy, and the Solar Modulation of Cosmic Rays

1968 ◽  
Vol 21 (6) ◽  
pp. 845 ◽  
Author(s):  
WR Webber
Keyword(s):  
Cosmic Rays ◽  
Radio Emission ◽  
Electron Spectrum ◽  
Cosmic Ray ◽  
Solar Modulation ◽  
Nonthermal Radio ◽  
The Galaxy ◽  
Nonthermal Radio Emission ◽  
Modulation Parameter ◽  
The Relationship

Utilizing recent measurements of the cosmic ray electron spectrum at the Earth and the effects of solar modulation on this spectrum, possible limits on the local interstellar electron spectrum have been determined. Synchrotron emission from these interstellar electrons is then compared with the local (disk) volume emissivity of nonthermal radio emission as deduced from a study of radio intensity profiles along the galactic equator. The detailed spectrum and magnitude of radio emissivity can be reproduced from the electron spectrum only for very stringent, conditions on the magnitude of the local interstellar magnetic field, and the amount of solar modulation of cosmic rays. Specifically it is found that B -L "'" 7 !-,G, and the residual modulation parameter KR "'" 0�75 GV. If solar modulation effects on the cosmic ray electron component are negligible then an implausibly high local field of "'" 20 !-,G is required.

scholarly journals Gamma-ray observations and massive stars

1999 ◽  
Vol 193 ◽  
pp. 205-217
Author(s):  
Roland Diehl
Keyword(s):  
Gamma Rays ◽  
Massive Star ◽  
Gamma Ray ◽  
Massive Stars ◽  
Cosmic Ray ◽  
Interstellar Space ◽  
Interstellar Matter ◽  
Spatial Profile ◽  
The Galaxy ◽  
Γ Ray

Gamma-rays from astrophysical sources testify energetic processes such as nucleosynthesis and cosmic ray collisions. Gamma-rays are observable from throughout the Galaxy, unattenuated by interstellar matter, provided their intensity exceeds the current instrumental sensitivity level (∼ 10−5ph cm−2s−1 at 1 MeV). Massive stars are at the origin of relevant sources: The all-sky image in the 1.809 MeV γ-ray line from radioactive 26Al traces nucleosynthesis throughout the Galaxy. The structure of this emission along the plane of the Galaxy suggests massive stars as dominating sources of this radioactivity. Discrimination of the contribution from core collapse supernova against that from WR-wind ejected hydrostatic nucleosynthesis products may be obtained from 60Fe γ-ray line observations, or from spatial-profile consequences of the metallicity dependence of 26Al production in theories for both source sites. As a single source, the nearest WR star in the γ2 Vel system is found to eject less 26Al into interstellar space than current theories predict. However, a more adequate comparison must be based on a time-dependent 26Al light-curve of the system. Furthermore, continuum γ-ray production in WR binaries through wind-wind interaction, and constraints on the low-energy cosmic ray origin in WR winds through characteristic nuclear deexcitation line studies are targets of research. Studies stimulated by COMPTEL'S 3–7 MeV excess report from the Orion region indicate that the γ-ray line measurements could separate the origins from supernova ejecta and wind material. The COMPTEL Orion result is now attributed chiefly to an instrumental artifact, and has been withdrawn. Nevertheless, the search for MeV emission from massive star clusters, as well as from interacting binaries such as WR 140, promises a unique test of particle acceleration scenarios related to the source mechanism for cosmic ray production.

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