Observations: Cosmic rays Martin Pohl

Topics Isotopic composition of cosmic rays Low-energy cosmic rays Injection into shock acceleration Structure of acceleration regions Antimatter Nucleosynthesis in accretion flows

Topics What is the flux of low-energy cosmic rays? Where exactly are cosmic rays produced?

Low-energy cosmic rays Antimatter production: Nucleosynthesis or cosmic-ray interactions? Positrons start with less than a few MeV High bulge/disk needs explanation

Low-energy cosmic rays Cosmic-ray interactions: Collisions with CNO, e.g. Production rate is 𝑸=𝟒𝝅 𝑵 𝑪𝑵𝑶 𝝈 𝝋 𝑪𝑹 Predictions for nuclear lines below current sensitivity

Low-energy cosmic rays Nucleosynthesis Should trace novae, WR stars, etc. Cosmic-ray interactions: Requires high flux of low-energy cosmic rays Could relate to spurious activity of Galactic center May explain excess ionization at Galactic center

CR production sites We know the process: Shock acceleration: Significant energy gain by multiple shock crossing Injection is key Role of dust?

Introduction Expansion into wind zone for core-collapse SNe Typ Ic: Wolf-Rayet progenitor

CR production sites Solar-system abundances 19% massive-star abund. + 81% SS Refractories preferred, Dust? Slope 0.6 Murphy et al. 2016

CR production sites Isotopic composition around 100 MeV/nuc 60Fe has half-life 2.6 106 yr Refractories preferred Dust? Slope 0.6 Binns et al. 2016

CR production sites 60Fe is produced in core-collapse and found in ejecta, not in wind Acceleration at reverse shock? High low-energy flux for small acceleration rate Composition enriched Problem: Most particles should be accelerated by forward shock at late phase Refractories preferred Dust? Slope 0.6

CR production sites 60Fe is produced in core-collapse and found in ejecta, not in wind Use 20% massive star / 80% solar system to estimate RMS (red) Production calculations in OB associations by Woosley & Heger Chieffi & Limongi OB associations needed? Little time for propagation to Earth Refractories preferred Dust? Slope 0.6 Binns et al. 2016

Summary What do we need to know? Positron yields by novae and other sites of nucleosynthesis Intensity of nuclear excitation lines Isotopic yields in supernova ejecta Dust formation in ejecta, winds, and OB associations Propagation properties of low-energy cosmic rays Location of nearby sources