Detection of gamma-ray lines from interstellar 60Fe by the high resolution spectrometer SPI
Publication date: 02 March 2005
Authors: Harris, M.J., et al
Journal: A&A
Volume: 433
Issue: 3
Page: L49-L52
Year: 2005
Copyright: ESO 2005
It is believed that core-collapse supernovae (CCSN), occurring at a rate ~once per century, have seeded the interstellar medium with long-lived radioisotopes such as 60Fe (half-life 1.5 Myr), which can be detected by the gamma-rays emitted when they beta-decay. Here we report the detection of the 60Fe decay lines at 1173 keV and 1333 keV with fluxes 3.7 ± 1.1 × 10-5 photons cm-2 s-1 per line, in spectra taken by the SPI spectrometer on board INTEGRAL during its first year. The same analysis applied to the 1809 keV line of 26Al yielded a line flux ratio 60Fe/26Al = 0.11 ± 0.03. This supports the hypothesis that there is an extra source of 26Al in addition to CCSN.
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