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The Mystery of Ultra-High Energy Cosmic Rays A New Window to the Extreme Universe

The Mystery of Ultra-High Energy Cosmic Rays A New Window to the Extreme Universe. Pablo Bauleo, Ph.D. Fort Collins, CO. Outline. Brief History of Cosmic Rays The Auger Observatory in Argentina Measurement techniques Auger released results. Pablo at age 5. Outline.

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The Mystery of Ultra-High Energy Cosmic Rays A New Window to the Extreme Universe

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  1. The Mystery of Ultra-High Energy Cosmic Rays A New Window to the Extreme Universe Pablo Bauleo, Ph.D. Fort Collins, CO

  2. Outline Brief History of Cosmic Rays The Auger Observatory in Argentina Measurement techniques Auger released results

  3. Pablo at age 5

  4. Outline Brief History of Cosmic Rays The Auger Observatory in Argentina Measurement techniques Auger released results

  5. Historical high points 1912 – Victor Hess discovers cosmic rays (subatomic particles coming from outer space) 1938 – Pierre Auger discovers Extended Air Showers (EAS) 1962 – Penzias & Wilson discover Cosmic Microwave Background Fast electronic counters

  6. Historical high points 1912 – Victor Hess discovers cosmic rays (subatomic particles coming from outer space) 1938 – Pierre Auger discovers Extended Air Showers (EAS) 1962 – Penzias & Wilson discover Cosmic Microwave Background Fast electronic counters PM Bauleo & JR Martino Nature458, 847-851 (2009) doi:10.1038/nature07948

  7. Historical high points 1912 – Victor Hess discovers cosmic rays (subatomic particles coming from outer space) 1938 – Pierre Auger discovers Extended Air Showers (EAS) 1962 – Penzias & Wilson discover Cosmic Microwave Background CMB is an “echo” of the Big Bang Source of Ultra High Energy Cosmic Rays must be < ~ 300 Mly away Fast electronic counters

  8. Ultra High Energy Cosmic Rays are rare • Low Energy (1011 eV) ~ 10 per feet2 sec • Mid Energy (1015 eV) ~ 1 per feet2 month • High Energy (1018 eV) ~ 1 per mile2 year • Ultra-High Energy (1020 eV) ~ 1 per mile2 century Solution: Think BIG! Build a 1200 square miles observatory Collect ~ 12 events/yr …. Or you have to wait 10,000 years to have one land in a baseball field

  9. Cosmic MysteriesWhere do Ultra High Energy Cosmic Rays come from? • No convincing acceleration process for explaining particle energy > 1019 eV • Sources of particles > 1019 eV must be closer than about 300 Mly because of CMB (~1% of distance to edge of observable universe) • The highest energy cosmic rays should point back to possible sources They exist! We should be able to see the sources Shouldn’t we just build an observatory and find them?

  10. 65 Institutions, ~300 Collaborators, 17 Countries, 4 Continents The Auger Collaboration Participating Countries Argentina Mexico Australia Netherlands Bolivia Poland Brazil Portugal Czech Republic Slovenia France Spain Germany United Kingdom Italy USA Vietnam

  11. Outline Brief History of Cosmic Rays The Auger Observatory in Argentina Measurement techniques Auger released results

  12. The Auger Observatory We are here Auger Observatory is here Malargue is a small town on the high plains not far from a ski area in the Andes.

  13. Southern Hemisphere  Southern Skies!

  14. Extracting information from an EAS • Tank timing • Arrival direction • Number of particles in tanks • Total Energy • Telescope image (digital camera like) • Arrival direction • Light detected • Total Energy • Redundant measurement for cross-checks Animation of an event measured in Argentina

  15. Hybrid Detector Tank Array + Telescopes1657 tanks & 27 Telescopes

  16. Tour of the Auger Observatory

  17. Auger Observatory – Southern Array 50 miles Subsystem 1 – Tank Array 1600 detector stations 1.5 km spacing 3000 km2 (1200 sq miles) Subsystem 2 – Fluorescence Telescopes 4 Telescope enclosures 6 Telescopes per enclosure 24 Telescopes total

  18. GPS antenna Communications antenna Electronics enclosure Solar panels Battery box 3 – nine inch photomultiplier tubes Plastic tank with 12 tons of water Subsystem 1 - The Tank Array

  19. GPS antenna Communications antenna Electronics enclosure Solar panels Battery box 3 – nine inch photomultiplier tubes Plastic tank with 12 tons of water Subsystem 1 - The Tank Array

  20. installation of electronics receiving ~20 tanks/week Water deployment Transportation into the field Tank Preparation and Assembly Installation Chain

  21. Vizcacha Real Deployment Story

  22. Another Real Story

  23. Subsystem 2 - The Fluorescence telescopes

  24. 3.4 meter diameter segmented mirror 440 pixel camera Aperture stop and optical filter Subsystem 2 - The Fluorescence telescopes

  25. Both subsystems are complementary • Tanks works 24/7 • Telescopes only in clear nights

  26. Outline Brief History of Cosmic Rays The Auger Observatory in Argentina Measurement techniques Auger released results

  27. Correlation of the Highest-Energy Cosmic Rays with Nearby Extragalactic Objects • Nature: • A top 10 story of 2007 • Science: • A top 3 discovery in 2007 • American Physical Society: • A top 3 discovery in 2007 Science, 318, p.938, 2007

  28. By the way, what is an AGN? • Active Galactic Nuclei (AGN) • Massive black hole in the center • High luminosity • Jets • Emission in X-Ray, Gamma Ray, visible, etc • Jets associated with black hole axis • Depending on jet orientation and spectra could be called: Blazar, Quasar, Seyfert, etc

  29. Correlation Map

  30. Aiming HighThe search for Ultra-HighEnergy Cosmic Rays

  31. Backup slides

  32. Auger Observatory Fun Facts

  33. An alternative funding strategy?

  34. Summary • Pierre Auger Observatory • 1200 square miles, 1600 surface stations, 27 optical detectors • Shed light on the mystery of cosmic rays • Studies of anisotropies in the sky (AGNs!) • Set limits on photon primaries • Primary mass analysis • GRB searches • Tau Neutrino analysis http://www.auger.org

  35. What does the correlation mean? (1) • Are AGN definitely the sources? • Any other objects with the same spatial distribution could be the source

  36. What does the correlation mean? (2) • What kind of AGN correlates with cosmic rays? • 15 out of 24 events seems to be coming from Seyfert galaxies, however still is not statistically significant

  37. Why Auger North? Measured arrival directions – Auger SouthFor full-sky coverage we need Auger North

  38. Why Colorado for the Northern Array? • Flat (easy deployment) • Large area available (>10000 km2) • Altitude & Latitude requirement • Infrastructure available, yet no polluted • Good atmospheric clarity • Recognition of CSU group excellent track record

  39. Display tanks in Southeast Colorado Lamar Community College – Lamar, Prowers County Bent County Fairgrounds – Las Animas, Bent County

  40. Pierre Auger Collaboration Recent Results (2009) • 16 scientific papers currently in preparation • Cosmic ray primary mass analysis • Cosmic ray spectrum analysis • GZK Horizon • Particle physics at ~300 TeV (Beyond LHC) • Galactic and extragalactic magnetic fields • Tau neutrino limit • …. • 17 technical papers currently in preparation • 21 scientific or technical papers already published • Photon flux limit • Galactic Center studies • Anisotropies • ….

  41. Search method and Prescription • Search for correlation with anything we could think of… • Correlation found with AGNs • 12th Edition Veron-Cetty Catalog of AGN and quasars • Distance less than 75 Mpc (z<0.018) • Deviation less than 3.10 • Energy larger than 57 EeV • Was it casual?  Prescription (ie, repeat the experiment)

  42. Author list and Event list Author list > Event list

  43. Astro-ph/0607382 Galactic Center & Anisotropies AGASA claim* +4.5 s (large circle) SUGAR claim** +2.9 s (small circle) • Auger sees no excess from the Galactic Center (Did it turn it off?) • -0.15 s for AGASA claim • -0.5 s for SUGAR claim * AGASA Coll, Astrop. Phys 10 (1999) ** SUGAR Coll, Astrop Phys 15 (2001)

  44. Zenith angle ~ 48º Energy ~ 70EeV Energy Determination and the Spectrum The energy scale is based on fluorescence measurements -based on N2 fluorescence yield- without reliance on a specific interaction model or assumptions about the composition. The detector signal size at 1000 meters from the shower core - called the ground parameter or S(1000) - is determined for each surface detector event using the lateral density function. S(1000) is proportional to the primary energy.

  45. Recent Auger Result Energy Determination and the Spectrum (2) The energy converter: Compare ground parameter S(1000) with the fluorescence detector energy. Transfer the energy converter to the surface array only events. The energy conversion heavily relies on the N2 fluorescence yield Hybrid Events Strict event selection: track length >350g/cm2 Cherenkov contamination <10% Log (E/EeV) 10EeV 1 EeV Log S(1000)

  46. DE/E~50% DE/E~30% Auger Energy Spectrum (ICRC 2005)

  47. Astro-ph/0606619 Astrop. Phys. (in press). Primary photon flux • “Top down” models predict large fraction of primaries are photons. • Photons result in deep Xmax position (SD: muon poor) • Present measurement based on sample of hybrid events – direct measurement of Xmax XMAX 16% upper limit on primary photon flux about 1019 eV. Confirms and improves previous limits by ground arrays

  48. Systematic Errors in the FD (Hybrid) Energy Normalization

  49. Atmospheric Monitoring and Calibration Atmospheric Monitoring Absolute Calibration Central Laser Facility Drum for uniform camera illumination – end to end calibration Lidar at each fluorescence eye

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