1520002

Cas A and Tycho are remnants of a core-collapse and a type Ia supernova explosion 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. 44Ti nucleosynthesis is assumed to occur in alpha-rich freeze-out from Si burning or NSE burning. The amount of 56Ni which also is produced in the supernova interior has been estimated indirectly together the 44Ti/56Ni ratio is a key diagnostic of the inner processes in a supernova explosion. Here we propose deep observations of the sky region including both Cassiopeia A and Tycho in order to (1) advance Cas A 44Ti line results to sufficient quality for line shape and line ratio tests that reflect inner ejecta kinematics and (2) obtain sufficient exposure for Tycho to confirm the 44Ti signal reported from other instruments in the hard X-ray range. The SWIFT detection of 44Ti from Tycho a SN Ia remnant adds to the puzzle of 44Ti synthesis and the origins of cosmic 44Ca. 44Ti deposits radioactive energy in nebular-phase supernova remnants through positrons but the escape of positrons into interstellar space is an issue. Our planned observations will (3) constrain any local positron annihilation in the remnant itself thus possibly explain the disk faintness in 511 keV gamma-rays. Young supernova remnants are also believed to be predominant sources of cosmic rays. Our observations aim (4) to search for direct evidence signs of local cosmic-rays within the remnants such as nuclear de-excitation gamma-ray lines and continuum emission from Bremsstrahlung. [truncated! Please see actual data for full text]