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Detection of gamma-ray lines from interstellar 60Fe by the high resolution spectrometer SPI

M. J. Harris·J. Knodlseder·P. Jean·E. Cisana·R. Diehl·G. G. Lichti·J. -P. Roques·S. Schanne·G. Weidenspointner
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Abstract

It is believed that core-collapse supernovae (CCSN), occurring at a rate about 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 x 10(-5) ph 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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M. J. Harris, J. Knodlseder, P. Jean, E. Cisana, R. Diehl, G. G. Lichti, J. -P. Roques, S. Schanne, G. Weidenspointner. 2005-02-28. Detection of gamma-ray lines from interstellar 60Fe by the high resolution spectrometer SPI. https://doi.org/10.1051/0004-6361%3A200500093

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