Ultra High Energy Cosmic Rays Theoretical Perspective(s) Angela V. Olinto CfCP, DAA, EFI University of Chicago

Outline n The Basics n The Recent Past n The Present n The Future (Perspectives)

The Basics ©S. Swordy Cosmic Rays exist! Still not clear where they come from Because of... Galactic Magnetic Fields But at Ultra High Energies... should be able to point back and see the SOURCES!

Ultra High Energy CRs trajectories O’Neil, A.O., Blasi ‘01 From Diffusive to Straight Line Isola, Lemoine, Sigl ‘02

Isotropic Distribution of Arrival Directions HiRes >10 18 eV AGASA >10 19 eV Still at ~10 20 eV (if protons)  extragalactic sources  interact with CMB  GZK feature! The Basics

High Energy Proton sees CMB as High Energy Gamma Rays! GZK Cutoff Greisen ‘66, Zatsepin & Kuzmin ‘66 p+  cmb   +  p +  0  n +  + The Basics  -resonance multi-pions

Extragalactic UHE Particles Protons, nuclei and gamma rays lose energy in intergalactic space Proton energy vs. distance (J. Cronin) Energy loss on Cosmic Microwave Background Protons: Photo Pion production off CMB p+  cmb    p/n+  Fe: photo-dissociation Infrared Background Photons: e + e - Radio Background The Basics

GZK Feature Blasi, A.O. ‘01 The Basics  E 3 Flux E 

The Recent Past 3 x eV “Super-GZK” event Hadronic Primary! Proton? Fe? Not  ? But only 1 event! Fly’s Eye 1992

AGASA The Recent Past A Theorist’s Field Day ~ 10 events above eV

Isotropic + small scale clustering? galactic plane supergalactic plane AGASA>4 x eV Red squares : events above eV, green circles : events of (4 – 10)x10 19 eV The Recent Past

Bottom-Up ZeVatrons Astrophysical Accelerators reach ZeV’s Energy: ≥ eV is the 1st challenge (If 1 TeV is hard imagine 10 9 TeV!!) Propagation: the 2 nd challenge B igm (determines the spectrum and arrival direction) Acceleration = Macroscopic motions transferred to particles a la Fermi Hillas plot: require particles to be contained, ie, Gyroradius < size of Accelerator Not many objects left: Neutron Stars AGNs Radio Lobes Clusters Colliding Galaxies/Clusters Gamma Ray Bursts The Recent Past

Hillas Plot Gyroradius < size of Accelerator The Recent Past

Neutron Stars: Young Neutron Star Winds? Crab Nebula with Chandra A Galactic Fe option! (A.O., Epstein, Blasi ’99, Blasi, Epstein, A.O. ’00) The Recent Past

Local Source Solution New Component From Local Source! E -2 E -1 The Recent Past

YNSWs COMPOSITION: Heavy, Fe SPECTRUM: Hard & No GZK feature GALACTIC correlations at highest energies But if Extra Galactic…protons Very Energetic (High B and  ) YNSWs cause extragalactic UHECRs, Rare events with E -1 spectrum  A Milky Way event ~ 10 6 flux  higher E > eV Association with GRBs... (Arons ‘02, Konigl et al ‘02) The Recent Past

AGNs: Central Regions High energy Photons observed - E max ≈ eV but too many losses (Norman,Melrose, Achterberg ‘95) GZK plus Cosmography hurt. Dead Quasars maybe but GZK cut! (Bolt & Ghosh ‘99) Radio Lobes E max ≤ eV (Rachen & Bierman ‘93) E max ≤ eV (Bierman ‘00) But, in general they are Too far!! Except for M87, Need very specific B Gal & B igm Other Extragalactic Sources: But GZK plus local Hot Spot!!!!!! The Recent Past

The Hot Spot The Recent Past

Cluster Accretion Shocks E max ≈ eV (Kang, Ryu, & Jones ‘96) Even if energy is close, they don’t get out (Blasi ‘99) Galactic Winds E max ≈10 19 eV (Jokopii & Morfill ‘85) Gamma Ray Bursts (Vietri ‘95, Waxman ‘95) Transient Relativistic Shocks Similar p &  emissivity But need more for UHECRs  E/E ~1 or needs B igm ≥ G E 20 /d 30 /l NO Clusters The Recent Past

BOTTOM -UP Galactic Neutron Stars Extragalactic Radio Lobes Gamma Ray Bursts Protons, Iron, nuclei? Hard Spectrum Strong Designer Magnetic Fields to Isotropize Clustering to be understood The Recent Past

Half & Half Aproach: New Particles from Astrophysical Zevatrons For Ex: Uhecrons - Heavy-quark composites (Chung, Farrar, & Kolb ‘98) FE shower development says: Not above 50 GeV (Albuquerque, Farrar, & Kolb ‘98) Monopoles (Weiler & Kephart‘96) No also: (FE shower development) Unless… (Wick, Kephart, Weiler & Bierman‘00) UHE Neutrinos scatter off background: Z-pole (Fargion ‘99, Weiler ‘99) Needs Very High Energy (High Flux) Neutrino Source (Sigl et al ‘02) Tests: No Clustering!!! Photon primaries The Recent Past

Top-Down Energy >> eV is Easy! (Usually start at eV or higher!!) Flux is the challenge!! (determined by typical separation scales ~ H 0 -1 ) & Composition!! Topological Defects generated in the early Universe through the Kibble Mechanism – as symmetries are broken. (Hill 83, Hill, Schramm 82, Hill, Schramm, & Walker 87, Bhattacharjee, Hill, Schramm 92, Sigl, Bhattacharjee, Schramm 94) Super Conducting Strings (Hill, Schramm &Walker ‘85) Cosmic Strings (Bhattacharjee & Rana ‘90) Monopolia(Hill 83, Bhattacharjee & Sigl 95) String Cusps(Brandenberger ‘87) Monop-String Network(Berezinsky Martin &Vilenkin97) Necklaces(Berezinsky & Vilenkin 97) Vortons(Masperi & Silva 98) Super Heavy Relic particles long lived – weakly interacting = CDM M x > GeV Metastable (Kuzmin &Rubakov 97; Berezinsky, Kachelriess, &Vilenkin 97) Dark Matter – Halo Distribution - small percentage decays today - Cryptons, … (Chung, Kolb, & Riotto 98, Kuzmin & Tkachev 98) The Recent Past

Super Heavy Relics Berezinsly, Blasi, Vilenkin `99 The Recent Past

Cosmic Necklaces Berezinsly, Blasi, Vilenkin `99 The Recent Past

Top-Down Signatures Composition: Photons >> Protons Spectrum: Hard QCD fragmentation NOT Power law like the Zevatrons! Cosmography: Halo Distribution!! (SHRs & Local TDs) or ~ Homogeneous No Clustering! Unless CDM clumps

Violation of Lorentz Invariance The Recent Past

HiRes Spectrum HiRes Collab ‘02 The Present

HiRes vs. AGASA Spectrum HiRes Collab ‘02 The Present

Exposures - systematics? Teshima ‘02 The Present

Systematic Errors below eV? Teshima ‘02 The Present

AGASA vs. HiRes I mono, HiRes II mono Teshima ‘02 The Present

UHECR: Discovery vs. Measurement Fly’s Eye & AGASA - may have Discovered a New Source of UHECRs HiRes - may have Measured the GZK cutoff "There are two possible outcomes: If the result confirms the hypothesis, then you've made a MEASUREMENT. If the result is contrary to the hypothesis, then you've made a DISCOVERY." Enrico Fermi The Present Auger - will Discover or Measure The Spectrum at EHEs

Theorists’ Attitudes n Theorist A n Theorist B n Theorist C n Theorist D

Theorist B

HiRes Collab ‘02 Theorist B Energy rescalings from 10 to 33%

HiRes Collab ‘02 Theorist B

Theorist B example  2 (one power law) =  2 (GRB) / 2 No AGASA data + re-scaling to Yakutsk data Bahcall & Waxman ‘02 DeMarco et al ‘02

Theorist C Blanton, Blasi, A.O. ‘01 Photo-Pion Production has large uncertainty with low statistics!!!!!!

Theorist C Blanton, Blasi, A.O. ‘01 + Evolution matters

DeMarco, Blasi, & A.O. ‘02 AGASA is better at probing the GZK feature than HiRes ‘02 Theorist C Even with larger aperture Statistics are too low

Auger x AGASA DeMarco, Blasi, A.O. ‘02 Theorist C

HORIZONTAL SHOWERS will probe Neutrino Cross Sections Above the Standard Model Tau showers from the Earth or the Andes Theorist D

Neutrino Fluxes Tyler, A.O., Sigl, ‘01 Theorist D

HE Cross Section Tyler, A.O., Sigl, ‘01 Limits on Large Extra Dimensions w/ Production of Mini Black Holes p-Branes… Feng, Shapere ‘01 Anh, Cavaglia, A.O.’02 and … Theorist D

Neutrinos at Auger Letessier-Selvon ‘00 Theorist D

EUSO Extreme Universe Space Observatory UHE Neutrinos! Theorist D

OWL Ni Fluorescence from ABOVE! = 30 x Auger 3000 events/year E > eV !!! UHE Neutrinos! Theorist D

JC pointing the way for ~10 yrs Theorist A

Just 1570 to go! Drives the Truck!

Theorist A’s other options

Hybrid Events & Horizontal Events Sun 9 Dec. 02:56: Auger sees first hybrid event Los Leones Bay 4 Tank Huron

The night before Jim Cronin’s event... !

11 Fold Event eV

Fly’s Eye saw 0 !! But there are GZK ’s!!    (10 19 eV) ≤ cm 2 Auger can reach ~   SM  probe interactions beyond Standard Model   (10 19 eV) ≥   SM ~ cm 2 Auger can also detect  decays!  ( eV) produce  ’s Andes (50 km) or Ground (upward  ’s)    Full mixing  GZK  ‘s !!! (Tyler, A.O., Sigl, ‘01)

The Telescope Array