1 / 34

Constraining UHECR source spectrum from observations in GZK regime

Constraining UHECR source spectrum from observations in GZK regime. Dmitri Semikoz APC , Paris & INR, Moscow. with M.Kachelriess and E.Parizot, arXiv:0711.3635. Overview:. GZK cutoff and anisotropy Horizon for protons and iron Model: protons from point-like sources

donald
Download Presentation

Constraining UHECR source spectrum from observations in GZK regime

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. Constraining UHECR source spectrum from observations in GZK regime Dmitri Semikoz APC , Paris & INR, Moscow with M.Kachelriess and E.Parizot, arXiv:0711.3635

  2. Overview: • GZK cutoff and anisotropy • Horizon for protons and iron • Model: protons from point-like sources • Can we find spectrum from 2-3 events per source? • Conclusions

  3. GZK cutoff and anisotropy

  4. pair production energy loss -resonance pion production energy loss multi-pion production pion production rate The Greisen-Zatsepin-Kuzmin (GZK) effect Nucleons can produce pions on the cosmic microwave background  nucleon • sources must be in cosmological backyard within 50-100 Mpc from Earth (compare to the Universe size ~ 5000 Mpc)

  5. HiRes: cutoff in the spectrum “GZK” Statistics 3 Expect 42.8 events Observe 15 events ~ 5 s 9 1 2 Bergman (ICRC-2005)

  6. Auger Energy Spectrum 2007 6s -----------------------------------------

  7. Arrival directions for E>57 EeV in Auger 8/13 P=0.16 % HiRes: no signal 2/13 events

  8. Global energy rescaling

  9. Arrival directions for E>40 EeV in HiRes (E>52 EeV in AGASA)

  10. Probability of correlation 3 s after penalty on angle M.Kachelriess and D.S., astro-ph/0512498

  11. Clustering signal in AUGER: 20-25 degree scales ~0.5 -1.5 %, ~70 events, Pierre Auger Collaboration, ICRC 2007

  12. Clustering signal in AUGER: scan 2% after scan and penalty between 7 and 23 degrees Pierre Auger Collaboration, ICRC 2007 Statistically limited at the moment. If real, connection to LSS and EGMF

  13. Horizon

  14. 50% of protons come from

  15. Horizon for protons 70%: approximations

  16. Horizon for protons: 90%

  17. Horizon for protons ----------------------------- ----------------------------- --------------------------------------------- Simulation with SOPHIA, stochastic energy losses, Assuming DE/E = 20% event by event

  18. Same true for heavy nuclei: Fe ----------------------------- Simulation by D.Allard

  19. Minimal UHECR model

  20. Protons can fit UHECR data V.Berezinsky, astro-ph/0509069 problem: composition ?

  21. Mixed composition model D.Allard, E.Parizot and A.Olinto, astro-ph/0512345 Problems: 1) escape of the nuclei from the source 2) How to accelerate Fe in our Galaxy

  22. Parameters which define proton flux • Proton spectrum from one source: • Distribution of sources:

  23. Potential problems: • Shock acceleration predicts 1/Ea with a=2-2.2, while spectrum fitted with a=2.5-2.6 • Linear acceleration even worth • It is very difficult to accelerate protons to E=1020 eV. Probably most of sources accelerate to lower energies.

  24. Acceleration of UHECR A.G.N. GRB • Shock acceleration: 1/Ea a=2-2.2 • Electric field acceleration: peak at Emax Radio Galaxy Lobe

  25. Protons from astrophysical sources • Most of UHECR with E> 1019 eV are protons • Spectrum of single source • Density of sources and their distribution • Distribution of maximum energy of sources Composition HiRes

  26. Protons from astrophysical objects:maximum energy of sources M.Kachelriess and D.S., hep-ph/0510188

  27. Protons from astrophysical objects:density of sources M.Kachelriess and D.S., hep-ph/0510188

  28. Looking for spectrum of sources

  29. Spectrum of protons from sources in 100 Mpc

  30. How to prepare data: • Take sources with some density • Propagate protons and deflect them in extragalactic and galactic magnetic fields • Convolve result with experimental exposure and take into account energy resolution. This produce CR dataset. • Take sources within some distance from Earth R< 100 Mpc. • Find all CR within some angle from those sources: some part is by chance(!)

  31. How to find probability: • We divide energy range in 2 bins: Emin<E<E20 and E>E20 • For every source at fixed distance we find binomial probability to emit N total CR with n CR in bin E>E20 for all sources with N>0 for several tested a • Multiply results for all sources • Compare results for different a

  32. Spectrum 1.1 vs 2.7 E>60 EeV

  33. 100 events E>60 EeV

  34. Conclusions • When sources of UHECR will be found, one can try to find acceleration spectrum of sources even 2-3 events come from any individual source • Typical number needed is 100 events with E>60 EeV to reject 1.1 from 2.7 at 99% C.L. in 95 % of cases. • In most of cases individual source would give up to 4 events in this dataset

More Related