1

The Pierre Auger ObservatoryCapturing Messengers from the Extreme

UniverseA new cosmic ray observatory designed for a high

statistics study of the

The Highest Energy Cosmic RaysUsing

Two Large Air Shower Detectors

Mendoza, Argentina (construction nearing completion)

Colorado, USA (in planning)

Gregory Snow / University of Nebraska

2

Auger north is planned in Colorado

Malargue is a small town on the high plains not far from a ski area in the Andes.

Auger south is here.

The Pierre Auger Observatory

3

The Auger Collaboration67 Institutions, 369 Collaborators

Argentina NetherlandsAustralia PolandBolivia* PortugalBrazil Slovenia Czech Republic SpainFrance United Kingdom Germany USAItaly Vietnam*

Mexico

* associate

True International Partnership - by non-binding agreement -

No country, region or institution dominates – No country contributes more than 25% to the construction.

4

Primary cosmic ray

Mostly muons, electrons and photons at Earth’s surface

Development of an extensive air shower in the Earth’s

atmosphere

5

How a cosmic-ray air shower is formed and detectedPrimary cosmic rays (mostly protons or light nuclei)

impinge on earth’s atmosphere from outer space

Grid of particle detectorsintercept and sample portion of secondaries

1. Number of secondaries related to energy of primary

2. Relative arrival time reveals incident direction

3. Depth of shower maximum related to primary particle type

“Air shower” of secondary

particles formed by collisionswith air molecules

6

Event timing and direction determination

7

Detecting Cosmic Ray Air Showers

Fly’s Eye

Surface Array

Air shower measurements are made by two techniques

1) Surface Arrays

2) Fluorescence Telescopes (Fly’s Eyes)

8

9

The Hybrid Design

• Nearly calorimetric energy calibration of the fluorescence detector transferred to the event gathering power of the surface array.

• A complementary set of mass sensitive shower parameters.

• Different measurement techniques force understanding of systematic uncertainties

• Determination of the angular and core position resolutions

Surface detector array + Air fluorescence detectorsA unique and powerful design

10

The Surface ArrayDetector Station

Communications antenna

Electronics enclosure

3 – nine inchphotomultipliertubes

Solar panels

Plastic tank with 12 tons of water

Battery box

GPS antenna

11

The Fluorescence Detector

11 square meter segmented mirror

Aperture stop and optical filter

440 pixel camera

FD telescopes in closedenvironment

Corrector lensminimizes sphericalaberrations, filterbrackets 350 nmfluorescence light

12

Installation nearly complete

As of October 20, 2007, 1500 of 1600 SD stations

13

Aerial Photos of Fluorescence BuildingsNovember 2006

1420 May 2007 E ~ 1019 eV

Event seen by all 4 fluorescencedetectors and many surface detectors

15

Major result from the Observatory will befeatured in the November 9 issue of Science (cover story)

“Correlation of the highest energy cosmic rays withnearby extragalactic objects”

Super-galacticplane Galactic

coordinates

16

Some details• AGN locations from “V-C” (Véron-Cetty and Véron) catalog, D < 75 Mpc• Data set 1 Jan. 2004 – 26 May 2006: 12 events among 15 with E > 56 EeV, Zenith angle < 60o correlate with AGN positions within 3.1o

3.2 expected by chance if flux were isotropic• Data set 27 May 2006 – 31 Aug. 2007: 8 among 13 events correlate, 2.7 expected from isotropic flux

• Probability to happen by chance 1.7 10-3

• Two events within 3o of Centaurus A, one of the closest AGNs

17

18

Centaurus A, D=3.4 Mpc

2 UHECRs correlated.

Infrared

X-ray

radio+optical images