Impact of cross section uncertainties on diffuse gamma-ray calculations

Timur DELAHAYE

Diffuse γ-ray emission

γ-ray emissivity

γ-ray emissivity

Nuclear enhancement factor

w(A₁,A₂) = (A₁×A₂)

(2.4/3)

Norbury & Townsend 2007 Nucl. Inst. Meth.

w(A₁,A₂) = (A₁ +A₂ -1)²

3/8

3/8

Ohrt & Buffington 1976 ApJ

Cross-sections

Badwhar Golden & Stephens 1977

parametrisation on data

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Kamae et alii 2007 ApJ

based on PYTHIA 6

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Huang et alii 2007 Astroparticle Phys.

based on DPMJET3 + 7 Δ&N resonnances

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Mori 2009 Astroparticle Phys.

based on DPMJET3

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p+p —> π⁰

Kachelriess & Ostapchenko 2012

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QGSJET-II-04

SIBYLL 2.1

Data are from Jæger, Colley, Hyman & Rest (1975)

p+p —> γ

Kachelriess & Ostapchenko 2012

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QGSJET-II-04

Kamae et al

Data are from Jaeger, Colley, Hyman & Rest (1975)

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and

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Campbell et alii (1973)

Conclusion

Uncertainties affecting γ-ray production cross-section are larger than the precision of astrophysical data

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Cosmic-rays are not only protons, interstellar gas is not only Hydrogene, we need more cross-sections and not only p+p —> γ.