UHE Cosmic Rays in the Auger Era

Vulcano Workshop 2010 - May, 23-29, 2010 UHE Cosmic Rays in the Auger Era Sergio Petrera, L'Aquila University email: sergio.petrera@aquila.infn.it

Vulcano Workshop 2010 - May, 23-29, 2010 UHE Cosmic Rays in the Auger Era Sergio Petrera, L'Aquila University email: sergio.petrera@aquila.infn.it Motivations Present status of the Pierre Auger Observatory The physics items: energy spectrum CR composition arrival directions Summary and outlook

The interest for UHECRs in three points E > 10 18 ev transition galactic/extragalactic origin GZK effect pointing to the sources (particle astronomy!?)

The interest for UHECRs in three points E > 10 18 ev transition galactic/extragalactic origin GZK effect pointing to the sources (particle astronomy!?) + GZK reduces the horizon

AGASA: stopped Jan. 2004 HiRes: stopped Apr 2006 Auger: operating Telescope Array: starting the all-particle spectrum ankle UHE few/km sq per century GZK

AGASA: stopped Jan. 2004 HiRes: stopped Apr 2006 Auger: operating Telescope Array: starting Exposures Exposures

The Pierre Auger Observatory

Auger South: the plan

3000 km 2 area Vulcano Workshop

Nitrogen fluorescence detected as shower develops Particles detected as they reach ground Auger detection techniques Fluorescence (50 W light bulb @ c) nearly calorimetric direct view of shower evolution 10% duty cycle Acceptance depends on energy + atmosphere Surface (10 12 particles over 20 km 2 ) 100% duty cycle Flat acceptance above threshold Indirect measurements of primary energy and mass (relies on simulation) Hybrid = surface + fluorescence

Observables at Auger

SD energy calibration based on FD profiles golden hybrid events (independently detected) energy systematic error ~22 % mostly from systematics of the FD detector (fluorescence yield, atmospheric transparency...) Energy Calibration

Water Cherenkov tank Rotomolded polyethylene tank 10 m 2 x 1.2 m of ultrapure water in a light diffusing Tyvek liner, 3 PMTs Photonis (9 diameter); Autonomous unit: solar panel+battery, GPS timing, communication antenna, electronics Max 10 W power consumption the Surface Detector

Schmidt Telescope using 11 m 2 mirrors the Fluorescence Detector UV optical filter (also: provide protection from outside dust) Camera with 440 PMTs (Photonis XP 3062)

the Fluorescence Detector Schmidt Telescope using 11 m2 mirrors UV optical filter (also: provide protection from outside dust) Camera with 440 PMTs (Photonis XP 3062)

Auger 2010 Construction ended Apr. 2008 Enhancements for Detection @ Low Energies: HEAT (High Elevation Auger Telescopes) AMIGA (Auger Muon and Infill Array) + AERA array of radio detectors

Auger 2010 Construction ended Apr. 2008 Enhancements for Detection @ Low Energies: HEAT (High Elevation Auger Telescopes) AMIGA (Auger Muon and Infill Array) + AERA array of radio detectors New R&D: MW fluorescence detection [after Gorham et al., PR D 78 (2008) 032007] Towards an FD with 100% duty cycle?

ENERGY SPECTRUM

the Energy Spectrum PLB 685 (2010) 239 Cutoff at ~10 19.6 ev significant with > 30

the Energy Spectrum Within the energy scale systematics

Comparison to Source Models

MASS COMPOSITION

Mass Composition: the principle X max photons protons Fe Energy

Mass Composition: the principle X max photons Data protons Fe X max Energy

Elongation Rate Measurement Auger and HiRes Xmax measurements are compatible within systematic uncertainties

Comparison with Hadronic Models PRL 104 (2010) 091101 Mass composition getting heavier HiRes PRL 2010 proton dominance above 1.6 EeV but... difficult to compare with HiRes due to different definitions of observables.

Comparison with Hadronic Models PRL 104 (2010) 091101 More about Mass Composition by Analisa Mariazzi

Photons: upper limits Top down models strongly constrained

Neutrinos: Earth skimming n t

ARRIVAL DIRECTIONS

Initial Anisotropy Searches Typical accuracy of reconstruction <1 No significant emission from Galactic Centre No broadband signals e.g. Dipole at any energy above 1 EeV e.g 1 < E < 3 EeV, Amplitude < 0.7% No clustering of the type claimed by AGASA No signal from BL Lacs as possibly seen by HiRes ICRC 2007 Summary: Previous reports have not been confirmed

Correlation with AGN's (2007) Based on a Prescribed Anisotropy Test: Correlation with Veron-Cetty-Veron AGN Catalog 20 out of 27 events E>57 EeV correlating within 3.1 degrees with z<0.017 AGN's Isotropy rejected with >99% C.L.

Correlation with AGN's (2010) Update of the Prescribed Anisotropy Test (correlation with VCV catalog of AGNs) 38% (21/55) correlate (post exploration) vs. 21% expected from isotropy correlation decreased but still incompatible with isotropy at 99% C.L.

More results on Correlations New paper in preparation: new catalogs, autocorrelation, CenA preliminary

Summary... High quality results on all the observables of UHECR's A comprehensive interpretation of the whole data still missing

Summary... High quality results on all the observables of UHECR's A comprehensive interpretation of the whole data still missing Much work to do... many more data...

and Outlook What's coming next?what's coming nex A new observatory: TA (Telescope Array) Auger South: low energy extension HEAT (3 high elevation telescopes) AMIGA (SD infill + muon detectors) +... Auger North: at Lamar (CO) undergoing evaluation Go to space!

and Outlook What's coming next?what's coming nex A new observatory: TA (Telescope Array) Auger South: low energy extension 576 scintillator HEAT detectors (3 high elevation telescopes) AMIGA (SD infill + muon detectors) +... 1.2 km Auger interval North: at Lamar (CO) undergoing evaluation Go to space! ~2.5 hours from SLC 3 (+2) Communication Towers 3 FD stations (atmospheric fluorescence telescopes) 30 km

Auger North

Auger North: comparison with other expts

Auger North: correlations above 60 EeV

Photon search

Auger North: Photon search