1. The signature of the nearby universe on the very high energy diffuse gamma sky Århus, November 2006 Troels Haugbølle haugboel@phys.au.dk Institute for Physics & Astronomy, Århus University Collaborators: Alessandro Cuoco, Hannestad S, Miele G, Serpico P D, Tu H

2. The (diffuse) cosmic gamma ray sky (as seen by EGRET) Energy spectra Angular distribution

3. Sources of the  -ray sky AGNs Micro Quasars Pulsars Dark matter annihilation? Supernova remnants (APOD 28/10 - 99) (astro-ph/0611813)

4. Why interest us for the diffuse  -ray sky? ● Glast is flying very soon (fall 2007) (energy range 10 MeV -> 500 GeV)

5. Why interest us for the diffuse  -ray sky? ● Glast is flying very soon (fall 2007) (energy range 10 MeV -> 500 GeV) ● Several ground based surveys telescopes are in operation or planned ● Milagro, HAWC, ARGO... Energy range > 500 GeV

6. Why interest us for the diffuse  -ray sky? ● Glast is flying very soon (fall 2007) (energy range 10 MeV -> 500 GeV) ● Several ground based surveys are in operation or planned ● Milagro, HAWC, ARGO... Energy range > 500 GeV ● Cross correlating the angular distribution of the flux with the local large scale structure and looking at the spectra of the flux, we can learn about the sources - be it AGNs, micro quasars, pulsars, decaying dark matter or...

7. Other gamma-ray observatories (with small field-of-view though) CANGAROO III (Australia & Japan) Spring 2004 4 telescopes 10 meters Ø Woomera, Australia Windhoek, Namibia HESS (Germany & France) Summer 2002 4 (  16) telescopes 12 meters Ø Roque de los Muchachos, Canary Islands MAGIC (Germany, Spain, Italy) Summer 2003 1 telescope 17 meters Ø Montosa Canyon, Arizona VERITAS (USA & England) 2005? 7 telescopes 10 meters Ø

8. Gamma Ray Propagation Photon interactions at TeV energies give a gamma horizon comparable in size to the GZK horizon The main interaction is:  -> e + e - Pair production with e + e - cascading. The gamma photons scatter on the extra- galactic background light. 10 TeV 1 TeV 100 GeV  =1

9. Given the density  of sources and the energy spectrum g[E] the intensity is For low z the flux above an threshold energy E cut is where W(E,z) is the window function Gamma Ray Propagation W z 3TeV 1TeV 300GeV Window Function

10. Using the large scale structure to predict the distribution of the  -ray flux The SDSS survey  1Gpc

11. The SDSS survey  1Gpc Using the large scale structure to predict the distribution of the  -ray flux

12. The large scale structure - on a sphere -

14. The PSCz survey Quality compared to the 2MASS: About 15.000 Gal. in PSCz against 1.5 millions in 2MASS, and less sky coverage....but better redshifts quality: Spectroscopic redshifts available in PSCz with negligible errors For 2MASS only photometry is available from which photometric redshifts are calculable only with great errors (typically 20-30%) Mask and sky distribution of the PSCz sources Redshift distribution and selection function

15. W z 3TeV 1TeV 3GeV Window Function = Combine W(E,z) and survey +

16. Synthetic sky maps (low-l angular powerspectrum)

17. Green band: 1-  Shot noise Points: a lm from PSCz

18. The angular powerspectrum for high l Using N-Body simulations or the Halo model we can repeat the analysis of the PSCz catalog. But without masks, noise, or resolution problems. Halo Model N-body Simulation

19. Summary ● Observations: GLAST is flying soon. Ground based survey telescopes are planned or working ● Theory: The Universe is opaque: The very high energy gamma rays originate at low redshift ● Hypothesis: Sources are sitting in the cosmic web. But how are they correlated with matter? ● Analysis: Using large redshift surveys with well understood systematics, we can make skymaps of the diffuse  ray sky in different scenarios ● Prediction: Using N-body/halo models we can predict the form of the angular powerspectrum for high l. Using surveys we can predict the low l ● Conclusion: Correlating the  -ray sky with the large scale structure we learn about the sources

20. Summary ● Observations: GLAST is flying soon. Ground based survey telescopes are planned or working ● Theory: Due to pair production the very high energy gamma rays originate at low redshift ● Hypothesis: Sources are sitting in the cosmic web. But how are they correlated with matter? ● Analysis: Using large redshift surveys with well understood systematics, we can make skymaps of the diffuse  ray sky in different scenarios ● Prediction: Using N-body/halo models we can predict the form of the angular powerspectrum for high l. Using surveys we can predict the low l ● Conclusion: Correlating the  -ray sky with the large scale structure we learn about the sources Green band: 1-  Shot noise Points: a lm from PSCz