Date:
Tue, 20/01/200912:15-13:15
Location:
Kaplun Bldg, seminar room, 2nd floor
An apparently "anomalous" cosmic-ray positron to electron ratio from mundane supernova remnants.
Recent measurements of the positron/electron ratio in the cosmic ray flux exhibits an apparent anomaly, known as the PAMELA anomaly, whereby the ratio increases with energy between 10 and 100 GeV. In contrast to the expectations of standard scenarios, in which positrons are secondary cosmic rays formed as the result of hadronic interactions between the primary cosmic ray protons formed in supernova remnants, and the interstellar medium (ISM) this ratio should decrease with energy. The positrons are therefore explained as evidence for either the decay product of massive weakly interacting massive particles (WIMPs) or a direct astrophysical source of pairs,such as pulsars. We will show, however, that once a realistic distribution for the cosmic ray sources is taken into consideration, we consistently predict the observed positron to electron ratio between 1 and 100 GeV, while abiding to different constraints such as the observed electron spectrum and the cosmic-rays cosmogenic age.
Recent measurements of the positron/electron ratio in the cosmic ray flux exhibits an apparent anomaly, known as the PAMELA anomaly, whereby the ratio increases with energy between 10 and 100 GeV. In contrast to the expectations of standard scenarios, in which positrons are secondary cosmic rays formed as the result of hadronic interactions between the primary cosmic ray protons formed in supernova remnants, and the interstellar medium (ISM) this ratio should decrease with energy. The positrons are therefore explained as evidence for either the decay product of massive weakly interacting massive particles (WIMPs) or a direct astrophysical source of pairs,such as pulsars. We will show, however, that once a realistic distribution for the cosmic ray sources is taken into consideration, we consistently predict the observed positron to electron ratio between 1 and 100 GeV, while abiding to different constraints such as the observed electron spectrum and the cosmic-rays cosmogenic age.