1 / 8

Can Solar 6 Li Really Be Explained by Galactic Cosmic Rays?

Can Solar 6 Li Really Be Explained by Galactic Cosmic Rays?. Tijana Prodanović University of Novi Sad, Serbia Brian D. Fields University of Illinois at Urbana-Champaign. July 5 th , 200 7 30 th ICRC, Merida, Mexico. Outline.

luisa
Télécharger la présentation

Can Solar 6 Li Really Be Explained by Galactic Cosmic Rays?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Can Solar 6Li Really Be Explained by Galactic Cosmic Rays? Tijana Prodanović University of Novi Sad, Serbia Brian D. Fields University of Illinois at Urbana-Champaign July 5th, 2007 30th ICRC, Merida, Mexico

  2. Outline • Standard 6Li origin: Galactic Cosmic-Ray (GCR) nucleosynthesis • New observations indicate new 6Li source • CR interactions: Li & gamma-rays connected • Use extragalactic gamma-ray background (EGRB) to constrain GCR made 6Li • EGRB allows only ~50% of solar 6Li to be made by GCRs! • New source? MW higher CR flux? Low-energy CR component? 30th ICRC, Mexico

  3. How Well Do We Understand 6Li? • 7Li origin: cosmic rays + BBN • But 6Li only made by cosmic rays via fusion and spallation • Standard assumption: 6LiSolarmade by Galactic CRs • But new observations indicate a 6LiSolar plateau? New source of 6Li needed? Asplund et al.(2006) 30th ICRC, Mexico

  4. Lithium Cosmic-Ray Interactions • Hadronic cosmic-ray interaction production of • Pionic Gamma Rays 6Li & pionic gamma-rays connected! 30th ICRC, Mexico

  5. Li-g-ray Connection • Any cosmic-ray source produces both gamma-rays and lithium • Connected essentially with ratio of reaction rates (Fields and Prodanović 2005) • Li abundance: local CR fluence • Diffuse extragalactic : CR fluence across Universe • Use gamma rays to constrain Li! 30th ICRC, Mexico

  6. Galactic CRs and 6Li : Results Prodanović & Fields (2006) • Pionic gamma-ray fraction • Normalized to the Milky Way (blue) • ~30% of the total EGRB (normal gal.) • 6Li production channels included • fusion • spallation • 2-step reactions, eg. • Account for astration • Gamma rays allow for only ~50% of 6Li to be produced by GCRs! 30th ICRC, Mexico

  7. Implications & Conclusions • Only ~ 50% of solar 6Li can be explained by GCRs without overproducing gamma-rays • Need new important 6Li source • Recent observations in halo stars: 6Li plateau? But at 10% level of solar (Asplund et al. 2006) • Milky Way GCR flux higher than the cosmic mean? • Implications for star-formation rate • Low-energy CR component? • Energetics and LiBeB ratio constraints 30th ICRC, Mexico

  8. Thank You! 30th ICRC, Mexico

More Related