scholarly journals INTEGRALSPI All‐Sky View in Soft Gamma Rays: A Study of Point‐Source and Galactic Diffuse Emission

2008 ◽  
Vol 679 (2) ◽  
pp. 1315-1326 ◽  
Author(s):  
L. Bouchet ◽  
E. Jourdain ◽  
J.‐P. Roques ◽  
A. Strong ◽  
R. Diehl ◽  
...  
Keyword(s):  
Point Source ◽  
Gamma Rays ◽  
Diffuse Emission

scholarly journals Gas-Čerenkov Detector for 10 to 100 MeV Gamma Rays

1971 ◽  
Vol 41 ◽  
pp. 77-78 ◽  
Author(s):  
H. Helmken ◽  
J. Hoffman
Keyword(s):  
Gamma Radiation ◽  
Point Source ◽  
Gamma Rays ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Plastic Scintillator ◽  
Spectral Information ◽  
Cerenkov Detector ◽  
Half Angle ◽  
Cerenkov Light

A gas-Čerenkov detector sensitive to gamma radiation above 10 MeV is currently undergoing final testing. The detector relies on the conversion and Compton scattering of gamma rays in a plastic scintillator and detecting the resulting electrons via the Čerenkov light they emit in a 2-m propane-gas column. Spectral information can be attained by varying gas pressure during the flight. The present detector is approximately 34″ in diameter, 91″ in length and weight 450 lb. At 20 MeV, an angular resolution of 6° half angle is expected. With an efficiency of 1 to 2%, a 10 hr balloon-borne system should achieve a point-source sensitivity of approximately 5× 10−5 photon cm−2 s−1 above 20 MeV. A satellite version of the detector is expected to have a sensitivity of approximately 1.3 × 10−5 photon cm−2 s−1 above 10 MeV for a 1-month galactic-plane scan mode. (Helmken and Hoffman, 1970.)

scholarly journals The Diffuse Emission and a Variable Ultraluminous X‐Ray Point Source in the Elliptical Galaxy NGC 3379

2005 ◽  
Vol 635 (2) ◽  
pp. 1053-1061 ◽  
Author(s):  
Laurence P. David ◽  
Christine Jones ◽  
William Forman ◽  
Steven S. Murray
Keyword(s):  
Point Source ◽  
Elliptical Galaxy ◽  
Diffuse Emission ◽  
X Ray

Diffuse Gamma Rays of Galactic and Extragalactic Origin: Preliminary Results from EGRET

1996 ◽  
Vol 168 ◽  
pp. 279-288
Author(s):  
P. Sreekumar ◽  
D.A. Kniffen
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Emission Model ◽  
Diffuse Emission ◽  
Interstellar Gas ◽  
Cosmic Ray Interactions ◽  
Galactic Model ◽  
Energy Gamma

The all-sky survey in high energy gamma rays (E>30 MeV) carried out by the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray Observatory provides for the first time an opportunity to examine in detail diffuse gamma-ray emission of extra-galactic origin. The observed diffuse emission at high galactic latitudes is generally assumed to have a galactic component arising from cosmic-ray interactions with the local interstellar gas and radiation, in addition to an isotropic component presumably of extragalactic origin. The galactic component can be estimated from a model of the interstellar medium and cosmic-ray distribution. Since the derived extragalactic spectrum depends very much on the success of our galactic model, the consistency of the galactic diffuse emission model is examined both spectrally and spatially with existing EGRET observations. In conjunction with this model, EGRET observations of the high latitude emission are used to examine the flux and spectrum of the residual extragalactic emission. This residual emission could be either truly diffuse in origin or could arise from accumulated emission from unresolved sources particularly in the light of EGRET observations showing the presence of numerous gamma-ray bright active galactic nuclei.

scholarly journals Chandra observations of the dwarf starburst and Wolf-Rayet galaxies NGC 4449 and NGC 5253

2003 ◽  
Vol 212 ◽  
pp. 751-752
Author(s):  
Lesley K. Summers ◽  
Ian R. Stevens ◽  
David K. Strickland ◽  
Timothy M. Heckman
Keyword(s):  
Point Source ◽  
Massive Stars ◽  
Stellar Winds ◽  
Diffuse Emission ◽  
X Ray ◽  
Complex Morphology ◽  
Hα Emission ◽  
Supernova Explosions ◽  
Source Populations

We present an analysis of the Chandra observations of two dwarf starburst, Wolf-Rayet galaxies (NGC 4449 and NGC 5253). We have identified at least three different classes of objects within the X-ray point source populations, and we have found the diffuse emission, resulting from the stellar winds and supernova explosions of massive stars, to have a complex morphology and to consist of several components. Comparison with the Hα emission suggests the presence of ~ kpc-scale wind-blown bubbles and ruptured superbubbles.

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