Galactic Cosmic Ray Origins and OB Associations: Evidence from SuperTIGER Observations of Elements Fe through Zr
arXiv:1608.08183 · doi:10.3847/0004-637X/831/2/148
Abstract
We report abundances of elements from Fe to Zr in the cosmic radiation measured by the SuperTIGER (Trans-Iron Galactic Element Recorder) instrument during 55 days of exposure on a long-duration balloon flight over Antarctica. These observations resolve elemental abundances in this charge range with single-element resolution and good statistics. These results support a model of cosmic-ray origin in which the source material consists of a mixture of 19\% material from massive stars and 81\% normal interstellar medium (ISM) material with solar system abundances. The results also show a preferential acceleration of refractory elements (found in interstellar dust grains) by a factor of 4 over volatile elements (found in interstellar gas) ordered by atomic mass (A). Both the refractory and volatile elements show a mass-dependent enhancement with similar slopes.
9 pages, 12 figures, 2 tables, accepted by ApJ