1. Interaction of Cosmic-Rays with the Solar System Bodies as seen by Fermi LAT Monica Brigida Bari University For the Fermi LAT Collaboration

2. Sources in the Solar System Sources: The Moon The Sun (quiet and/or flaring) The Earth Potential Sources Asteroids in different populations: Main Asteroid Belt (MBAs) Jovian and Neptunian Trojans (Trojans) Kuiper Belt Objects (KBOs) Other planets Debris (< few meter size, dust, grains) MBAs, Trojans, KBOs Oort Cloud 2 M.Brigida - ICATPP 2010

3. Non flaring Sources in the Solar System Non flaring sources in the Solar System are bright in gamma rays due to their interaction with Galactic cosmic rays (CR) Moon gamma ray emission depends on the flux of CR nuclei near its surface Quiet solar gamma ray emission has two components: IC due to the CR electron scattering off solar photons in the heliosphere and the CR nuclei interactions with the solar atmosphere Gamma ray emission studies are a sensible probe for CR fluxes in the solar system Gamma ray flux measurements depends on the solar cycle 3 M.Brigida - ICATPP 2010

4. Solar activity and Cosmic rays Max solar activity ‐ > min cosmic ‐ ray flux Min solar activity ‐ > max cosmic ‐ ray flux The gamma ‐ ray flux depends on CRs flux intensities ‐ Solar Activity is now increasing from its minimum ‐ Solar Activity expected to peak around 2012 4 M.Brigida - ICATPP 2010

5. Emission Models “γ-ray emission” due to CR interactions with surface material: Moon rock (solid) Solar atmosphere (gaseous) Lunar -ray emission: Decay of neutral pions and Kaons, bremsstrahlung by electrons and Compton scattering of secondary photons Similar emission mechanism for any solid object in Solar System CR γ 5 M.Brigida - ICATPP 2010

6. 6 Gamma rays from the Moon Gamma rays from the Moon soft gamma rays ‐ > coming from the central part of the lunar disk high gamma rays ‐ > likely produced by CRs hitting the lunar surface with an almost tangential trajectory (the lunar disk limb). EGRET detected the Moon (Thompson ‘97) Flux(>100MeV) = 4.5x10 -7 cm -2 s -1 Moskalenko&Porter ’07

7. Quiet Solar emission: pion decay Solar disk emission due to interactions of CR particles with solar atmosphere (Seckel ’91) 7 M.Brigida - ICATPP 2010 CR γ Seckel ‘91 This component is therefore localized in the solar disk (almost pointlike )

8. M.Brigida - ICATPP 2010 8 Sun: second component Inverse Compton Scattering ©UCAR Inverse-Compton scattering of solar photons in the heliosphere by Galactic CR electrons: the emission is predicted extended Electrons are isotropic Photons have a radial angular profile e Moskalenko ’06 Orlando&Strong’08

9. Detection of the Sun with EGRET ‐ In agreement with theoretical models of IC and disk ‐ Detection of both IC and disk, but low statystics Orlando & Strong F_IC(>100MeV) =(3.8+/-2.2)x10 -7 cm -2 s -1 In 10 degrees radius F_disk(>100MeV) = (1.8+/-1.1)x10 -7 cm -2 s -1 9 M.Brigida - ICATPP 2010

10. Fermi Data Selection Data from Aug 4, 2008 until February 4, 2010 Analysis in celestial relative coordinates SUN is moving about 1°/day MOON is moving about 15°/day  (Moon and Sun centered data) E > 100MeV Zenith angle < 105° Galactic Plane Cut (>30°) Moon-Sun angular separation >20° ROI: 20° 10 M.Brigida - ICATPP 2010

11. Background Determination  The “fake” source method:  A fake source follow the path of the real source but 30 degrees away (passes through the same areas on the sky but at different times) M.Brigida - ICATPP 2010 11

12. M.Brigida - ICATPP 2010 12 Fermi: the Sun track in the sky

13. The Sun Observation 13 M.Brigida - ICATPP 2010 Sun Centered data Compared with the background fakesun AllSky simulation (i.e. taking into accout all 1FGL sources and the diffuse component)

14. The Sun Spectrum: the disk component 14 M.Brigida - ICATPP 2010 Flux(>100MeV)=(4.86 ± 0.14(stat) ± 0.97(syst)) x 10 -7 cm -2 s -1 Point component modeled with a PL2, taking into account the PSF

15. Angular profiles: evidence of extended emission Missing extended component Good description of the background

16. - Data - BKG - BKG+point source - Disk Component - IC Component - BKG+IC+point Angular profiles: evidence of extended emission E>100MeV

17. Results: the IC component Maximun Likelihood fit results: IC Flux(>100MeV)=(5.66 ± 0.61(stat)±2.26(syst))x10 -7 cm -2 s -1 IC Model with different solar modulation, based on the electron spectrum measured by Fermi/LAT above 7 GeV (Abdo et al. 2010) Inverse Compton spectrum from within 16 deg from the Sun

18. PRELIMINARY Moon Observation and Spectrum 18 M.Brigida - ICATPP 2010 PRELIMINARY PRELIMIARY 18 PRELIMINARY F (>100MeV) = (1.21 ± 0.02 stat ± 0.2 syst) × 10 ‐ 6 cm ‐ 2 s ‐ 1

19. The brightest γ-ray source on the sky: the Earth 19 M.Brigida - ICATPP 2010

20. Earth’s gamma-ray emission from CR interactions in the atmosphere Expect a power-law from the limb above ~5 GeV following the CR spectrum Earth’s gamma-ray emission from CR interactions in the atmosphere Expect a power-law from the limb above ~5 GeV following the CR spectrum Earth emission observations and energy response intensity maps 20 M.Brigida - ICATPP 2010

21. Gamma rays from small solar system bodies To probe the interstellar spectrum of CR protons (Moskalenko&Porter ’08) 21 M.Brigida - ICATPP 2010

22. Conclusions With the Fermi/LAT we observed the gamma ray emission from the Earth, the Moon and the Sun Continuous monitoring of the gamma ‐ ray sources for the solar cycle 24th will bring information on CR propagation in the heliosphere and across the inner Solar System Paper on the Moon and the Sun will BE SUBMITTED SOON! 22 M.Brigida - ICATPP 2010