Fields GLAST Argonne

THE HISTORY OF COSMIC RAYSIN NORMAL GALAXIESGAMMA-RAY AND LITHIUM FOSSILS: 

THE HISTORY OF COSMIC RAYS IN NORMAL GALAXIES GAMMA-RAY AND LITHIUM FOSSILS Brian Fields U Illinois Tijana Prodanovic U of Novi Sad Vasiliki Pavlidou U Chicago John Beacom Ohio State U

Guaranteed Gamma-Ray Background from Cosmic Rays: 

Guaranteed Gamma-Ray Background from Cosmic Rays Guaranteed extragalactic backgrounds unresolved high-z counterparts to confirmed low-z sources AGN Stecker andamp; Salamon, Mukherjeee andamp; Chaing, Pohl Normal Galaxies Pavlidou andamp; BDF Normal Galaxies Milky Way resolved spatially andamp; spectrally Gamma emission from cosmic rays both hadronic and leptonic relative contributions unclear no pion bump

Cosmic-Ray Sources Across the UniversePavlidou & BDF: 

Cosmic-Ray Sources Across the Universe Pavlidou andamp; BDF Modeling the cosmic history of cosmic-ray interactions supernovae as cosmic-ray sources interstellar medium as targets both fixed by cosmic star formation rate normalize to Milky Way CR/SN efficiency Results Pavlidou andamp; BDF galaxies’ contribution peaks ~0.5 GeV offset from MW peak: distinguishable near peak, ~30% of EGRET background (AGN) GLAST: more AGN resolved galaxy peak emerges cosmic-ray signal sums hadronic+leptonic but can we separate them?

Paleolithography:Lithium Probes of Cosmic-Ray HistoryProdanovic & BDF: 

Paleolithography: Lithium Probes of Cosmic-Ray History Prodanovic andamp; BDF Hadronic gamma production inevitably means lithium synthesis Observables gammas: measure mean CR fluence across universe lithium abundance: measures local CR fluence Complementary: use one to probe the other

Milky Way Cosmic-Ray Anomaly: 

Milky Way Cosmic-Ray Anomaly Lithium as Milky-Way Dosimeter 6Li: cosmic rays are only conventional nucleosynthesis source alternative: dark matter decays in early universe link demands pionic production Local cosmic-ray exposure andgt; avg galaxy Milky Way anomalously high hadronic CR actvity? Turn the problem around if Milky Way not greatly anomalous expect large normal galaxy gamma signal

Extrasolar Hadronic Cosmic Rays Still Undetected in Gamma Rays: 

Extrasolar Hadronic Cosmic Rays Still Undetected in Gamma Rays Unambiguous hadronic signature: pion bump But pion bump unseen anywhere Milagro Galactic TeV signal inconsistent with local cosmic-rays Unresolved point sources?

GLAST Impact: 

GLAST Impact Extragalactic diffuse background sensitivity, angular resolution: better foreground separation intensity, spectrum probes normal galaxies AGN resolved foreground lowers AGB background contribution, galaxies stand out Local Galaxies Multiple Local Group galaxy detections tests cosmic-ray dependence on local environment (star formation) and universality of cosmic-ray confinement Milky Way better diffuse/point source separation identification of pion bump?

The History of Cosmic Rays in Normal GalaxiesConclusions: 

The History of Cosmic Rays in Normal Galaxies Conclusions Extragalactic cosmic rays at cusp of revolution Smoking Gun: cosmic-ray/ISM interactions extragalactic background global CR history abundances local CR history GLAST will provide crucial new information pionic component reveals hadrons andamp; encodes history with 6Li probes Milky Way anomaly all other survey data (diffuse and point sources) will contribute new insight