1320004

Cas A and Tycho are remnants of a core-collapse and type Ia supernova respectively. Radioactive 44Ti has been observed from these two relatively young supernova remnants and is believed to originate from the deep interiors of supernova explosions representing physical conditions that are otherwise difficult to explore if at all.Here we propose to simultaneously observe Cassiopeia A and Tycho in order to (1) bring Cas A results to sufficient quality for line shape and line ratio tests that can probe inner ejecta kinematics in unique ways and (2) obtain sufficient exposure for Tycho to confirm the results reported from other instruments in the hard X-ray range. 44Ti nucleosynthesis is assumed to occur in alpha-rich freeze-out from Si burning or NSE burning and was believed to be characteristic for core-collapse interiors. However in the Galaxy feewer 44Ti bright sources are seen than expected from core-collapse supernova statistics. Moreover the detection of 44Ti from Tycho a SN Ia remnant adds to the puzzle of 44Ti synthesis and the origins of cosmic 44Ca. Additionally the survey in 511 keV emission from positron annihilation with INTEGRAL has shown the disk being a rather faint source of positron annihilation emission leading to the question if positrons from radioactive decays of + unstable isotopes may be contained in their sources and not leak out into interstellar medium of the Galaxys disk. Our planned observations will (4) constrain any local positron annihilation in the remnant itself thus possibly explain the disk faintness in 511 keV gamma-rays. [truncated! Please see actual data for full text]