Al26, Fe60 and Ti44: three gamma ray emitters that can disclose many secrets of their parents: what we know and what we would like to know

by Dr Alessandro Chieffi (IAPS - Istituto di Astrofisica e Planetologia Spaziali)

Wednesday 24 Oct 2012, 10:30 → 11:30 Europe/Rome

Rostagni meeting room (INFN-LNL)

The quest for the main source(s) of Al26 started as soon as the first observational evidence of the presence of live Al26 in the inner Galaxy was demonstrated by the HEAO 3 experiment. The launch of the CGRO in 1991, and its continuous operation up to 2001, allowed the first mapping of the 1809 KeV line all over the Galaxy and put firm constraints on the possible main sources of this gamma ray emitter. Together with the search for a signal from the decay of Al26, also a signal from Fe60 has been searched for thoroughly. Unfortunately, all the experiments up to 2002 could only provide upper limits on the abundance of this nucleus in the interstellar medium. With the launch of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and of the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) the situation changed drastically since both RHESSI and SPI aboard INTEGRAL were able to measure an Fe60 signal from the inner radiant of our Galaxy. I will discuss in some detail the most probable sources of the presently alive Al26 and Fe60 in the Galaxy and, in particular, the evolutionary phases and the nuclear processes involved in their synthesis. Eventually, I'll briefly discuss also the elusive gamma ray emitter Ti44 and its quite problematic synthesis.