Swift/BAT detection of hard X-rays from Tycho's Supernova Remnant:   Evidence for Titanium-44
  We report Swift/BAT survey observations of the Tycho's supernova remnant, performed over a period of 104 months since the mission's launch. The remnant is detected with high significance (>10 sigma) below 50 keV. We detect significant hard X-ray emission in the 60-85 keV band, above the continuum level predicted by a simple synchrotron model. The location of the observed excess is consistent with line emission from radioactive Titanium-44, so far reported only for Type II supernova explosions. We discuss the implications of these results in the context of the galactic supernova rate, and nucleosynthesis in Type Ia supernova. 
E. Troja, A. Segreto, V. La Parola, D. Hartmann, W. Baumgartner, C.   Markwardt, S. Barthelmy, G. Cusumano, N. Gehrels
astro-ph.HE