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Title:
Gamma-ray imaging observations of the Crab and Cygnus regions
Authors:
McConnell, Mark Lewis
Affiliation:
AA(New Hampshire Univ., Durham.)
Publication:
Ph.D. Thesis New Hampshire Univ., Durham.
Publication Date:
00/1987
Category:
Astronomy
Origin:
STI
NASA/STI Keywords:
CRAB NEBULA, CYGNUS CONSTELLATION, GAMMA RAY SPECTRA, GAMMA RAY TELESCOPES, LINE SPECTRA, STELLAR SPECTRA, BALLOON-BORNE INSTRUMENTS, ELECTRON ENERGY, ENERGY SPECTRA, SPECTROSCOPIC TELESCOPES, X RAYS
Bibliographic Code:
1987PhDT.........4M

Abstract

The results are presented from a balloon borne experiment, referred to as the Directional Gamma Ray Telescope, which is designed to image celestial gamma rays over the energy range 160 keV to 9.3 MeV. It utilizes a technique known as coded aperture imaging in order to obtain spatially resolved images of the sky with an angular resolution of 3.8 deg. This detector is the first flight-ready instrument of this type operating at energies obove 160 keV. During 30 hrs in which the payload remained at float altitude, imaging observations of a number of sky regions were obtained, including observations of the Crab and Cygnus regions. The Crab Nebula was observed to have a featureless powerlaw spectrum with a best fit form of 5.1 x .001 EMeV/1.88 photons/sq cm/s/MeV. Emission from Cyg X-1 was observed up to approx. 10 MeV. At energies below 1 MeV, the data are consistent with a single temperature inverse Compton model, with an electron temperature of approx. 80 keV and an optical depth of approx. 2.0. The inverse Compton model is often employed to explain the observed X-ray emission. In the 2 to 9.3 MeV range, the DGT results show emission which is not understood in the context of the inverse Compton model.
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Database: Astronomy
Physics
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