44Ti Decay Gamma Ray Lines in Cas A
With a lifetime of 86 years, 44Ti emits three gamma-ray lines at 67.9, 78.4 (from 44Sc) and 1157 keV (from 44Ca), observable with SPI and IBIS onboard INTEGRAL.
Top: IBIS/ISGRI images (2.5°×2.5°) centred on the supernova remnant Cassiopeia A (Cas A) in six energy bands:
- 63.5 - 65.5 keV
- 65.5 - 69.5 keV
- 69.5 - 73.5 keV
- 73.5 - 75.5 keV
- 75.5 - 79.5 keV
- 79.5 - 85.5 keV
The images containing the two 44Sc lines at 67.9 and 78.4 keV clearly show the enhanced emission from Cas A at these energies. The linear scale is the same for all six images.
Bottom: IBIS/ISGRI spectrum of Cas A and the best-fit model (solid red line) with the following boundaries: 21, 24, 28, 34, 39.5, 50, 63.5, 65.5, 69.5, 73.5, 75.5, 79.5, 85.5, 109.5, and 201 keV. The count rates and the model have been divided by the effective ISGRI area at the center of each channel, in order to obtain approximate flux density units. The upper limit above 110 keV is given at the 3σ confidence level.
Image from M. Renaud et al. .