Al(26) Studies with INTEGRAL's Spectrometer SPI
/ Authors
R. Diehl, K. Kretschmer, G. Lichti, V. Schonfelder, A. Strong, A. Kienlin, J. Knodlseder, P. Jean, V. Lonjou, G. Weidenspointner
and 6 more authors
J. Roques, G. Vedrenne, S. Schanne, N. Mowlavi, C. Winkler, C. Wunderer
/ Abstract
Al(26) radioactivity traces recent nucleosynthesis throughout the Galaxy, and is known to be produced in massive stars and novae. The map from its decay gamma-ray line suggests massive stars to dominate, but high-resolution line spectroscopy is expected to supplement imaging of Al(26) source regions and thus to help decide about the Al(26) injection process and interstellar environment, hence about the specific massive-star subgroup and phase which produces interstellar Al(26). The INTEGRAL Spectrometer SPI has observed Galactic Al(26) radioactivity in its 1809 keV gamma-ray line during its first inner-Galaxy survey. Instrumental background lines make analysis difficult; yet, a clear signal from the inner Galaxy agrees with expectations. In particular, SPI has constrained the line width to exclude previously-reported line broadenings corresponding to velocities >500 km/s. The signal-to-background ratio of percent implies that detector response and background modeling need to be fine-tuned to eventually enable line shape deconvolution in order to extract source location information along the line of sight.
Journal: arXiv: Astrophysics