Gamma-Ray Line Astronomy
Abstract
Gamma-ray lines from radioactive isotopes, ejected into interstellar space by cosmic nucleosynthesis events, are observed with new space telescopes. The Compton Observatory had provided a sky survey for the isotopes 56Co, 22Na, 44Ti, and 26Al, detecting supernova radioactivity and the diffuse glow of long-lived radioactivity from massive stars in the Galaxy. High-resolution spectroscopy is now being exploited with Ge detectors: Since 2002, with ESA's INTEGRAL satellite and the RHESSI solar imager two space-based Ge-gamma-ray telescopes are in operation, measuring Doppler broadenings and line shape details of cosmic gamma-ray lines. First year's results include a detection and line shape measurement of annihilation emission, and 26Al emission from the inner Galaxy and from the Cygnus region. 60Fe gamma-ray intensity is surprisingly low; it may have been detected by RHESSI at 10% of the 26Al brightness, yet is not seen by INTEGRAL. 44Ti emission from Cas A and SN1987A is being studied; no other candidate young supernova remnants have been found through 44Ti. 22Na from novae still is not seen.
Cite
@article{arxiv.astro-ph/0409674,
title = {Gamma-Ray Line Astronomy},
author = {Roland Diehl},
journal= {arXiv preprint arXiv:astro-ph/0409674},
year = {2009}
}
Comments
9 pages, 5 figures; invited review at "Nuclei in the Cosmos 8", Vancouver, CA; accepted for publication in Nucl Phys A