SPI Measurements of Galactic 26Al

Abstract

The precision measurement of the 1809 keV gamma-ray line from Galactic ${}^{26}$Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge detector camera. We aim for determination of the detailed shape of this gamma-ray line, and its variation for different source regions along the plane of the Galaxy. Data from the first part of the core program observations of the first mission year have been inspected. A clear detection of the \Al line at about 5--7 $\sigma$ significance demonstrates that SPI will deepen \Al studies. The line intensity is consistent with expectations from previous experiments, and the line appears narrower than the 5.4 keV FWHM reported by GRIS, more consistent with RHESSI's recent value. Only preliminary statements can be made at this time, however, due to the multi-component background underlying the signal at \about 40 times higher intensity than the signal from Galactic ${}^{26}$Al.

arXiv comment5 pages, 8 figures; accepted for publication in A&A (special INTEGRAL volume)

References in corpus (4)

• Early SPI/INTEGRAL contraints on the morphology of the 511 keV line emission in the 4th galactic quadrant
• SPI/INTEGRAL in-flight performance
• INTEGRAL/SPI ground calibration
• The Reuven Ramaty High Energy Solar Spectroscopic Imager observation of the 1809 keV line from Galactic 26Al

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• Observation of Diffuse Cosmic and Atmospheric Gamma Rays at Balloon Altitudes with an Electron-tracking Compton Camera
• 26Al in the inner Galaxy
• A Comprehensive Search for Gamma-Ray Lines in the First Year of Data from the INTEGRAL Spectrometer
• Measuring 26Al and 60Fe in the Galaxy
• Development of Convolutional Neural Networks for an Electron-Tracking Compton Camera
• Very massive star winds as sources of the short-lived radioactive isotope ${}^{26}$Al
• Galactic Population Synthesis of Radioactive Nucleosynthesis Ejecta
• Line shape diagnostics of Galactic 26Al
• Measurement of 25Mg(p; gamma)26Al resonance strengths via gamma spectrometry
• Gamma-Ray Line Astronomy
• SPI Measurements of Nucleosynthesis Gamma-Rays
• Cosmic Radioactivity and Galactic Chemical Evolution