Ultra High Energy Cosmic RaysTheoretical Perspective(s)

Angela V. OlintoCfCP, DAA, EFI

University of Chicago

Outline

The Basics The Recent Past The Present 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

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Isotropic Distribution of Arrival Directions

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HiRes >1018 eV

AGASA >1019 eV

Still at ~1020 eV (if protons) extragalactic sources interact with CMB GZK feature!

The Basics

High Energy Proton sees CMB as High Energy Proton sees CMB as High Energy Gamma Rays! High Energy Gamma Rays!

GZK CutoffGZK Cutoff

Greisen ‘66, Zatsepin & Kuzmin ‘66

p+cmb + p + 0

n + +

The Basics

-resonance

multi-pions

Extragalactic UHE ParticlesProtons, 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-dissociationInfrared Background

Photons: e+e -

Radio Background

The Basics

GZK Feature

Blasi, A.O. ‘01

The Basics

E3 Flux

E

The Recent Past

3 x 1020 eV“Super-GZK” event

Hadronic Primary! Proton? Fe? Not ?But only 1 event!

Fly’s Eye

1992

AGASAThe Recent Past

A Theorist’s Field Day

~ 10 events above 1020 eV

Isotropic + small scale clustering?

galactic plane

supergalactic plane

AGASA>4 x 1019 eV

Red squares : events above 1020 eV, green circles : events of (4 – 10)x1019 eV

The Recent Past

Bottom-Up

ZeVatrons Astrophysical Accelerators reach ZeV’s

Energy: ≥ 1020 eV is the 1st challenge(If 1 TeV is hard imagine 109 TeV!!)

Propagation: the 2nd challenge Bigm (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

AGNsRadio Lobes

ClustersColliding 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 ComponentFrom Local Source!

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E-2

E-1

The Recent Past

YNSWsCOMPOSITION: 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 ~ 106 flux higher E > 1014 eV

Association with GRBs ...

(Arons ‘02, Konigl et al ‘02)

The Recent Past

AGNs:

Central Regions High energy Photons observed -

Emax≈1019-20 eV but too many losses

(Norman,Melrose, Achterberg ‘95)GZK plus Cosmography hurt.

Dead Quasars maybe but GZK cut!

(Bolt & Ghosh ‘99)

Radio Lobes

Emax≤ 1021 eV (Rachen & Bierman ‘93) Emax≤ 1022 eV (Bierman ‘00)

But, in general they are Too far!! Except for M87,

Need very specific BGal & Bigm

Other Extragalactic Sources:

But GZK plus local Hot Spot!!!!!!

The Recent Past

TheHot Spot

The Recent Past

Cluster Accretion Shocks

Emax≈1019-20 eV (Kang, Ryu, & Jones ‘96)

Even if energy is close, they don’t get out (Blasi ‘99)

Galactic Winds

Emax≈1019 eV (Jokopii & Morfill ‘85)

Gamma Ray Bursts (Vietri ‘95, Waxman ‘95)

Transient Relativistic Shocks

Similar p & emissivity

But need 102-103 more

for UHECRs

E/E ~1 or

needs Bigm ≥ 10-10 G E20/d30 /l10.5

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 >> 1020 eV is Easy! (Usually start at 1023 eV or higher!!)

Flux is the challenge!! (determined by typical separation scales ~ H0-1)

& Composition!!

Topological Defectsgenerated 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 Mx > 1012 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

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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 1019eV?

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

Theorist A Theorist B Theorist C 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 ExtraDimensions w/Production of Mini Black Holesp-Branes…

Feng, Shapere ‘01Anh, Cavaglia, A.O.’02and …

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 > 1020eV !!!

UHE Neutrinos!

Theorist D

JC pointing the way for ~10 yrs

Theorist A

Theorist A

Just 1570 to go!

Drives the Truck!

Theorist A’s other options

Hybrid Events & Horizontal Events

Sun 9 Dec. 02:56:45 2001 - Auger sees first hybrid event

Los Leones Bay 4 Tank Huron

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

11 Fold Event 2.6 1019 eV

Fly’s Eye saw 0 !! But there are GZK ’s!!

(1019eV) ≤ 5 10-29cm2

Auger can reach ~ SM probe interactions beyond Standard

Model

(1019eV) ≥ SM ~10-30-31cm2

Auger can also detect decays!

(1017-18eV) produce ’s

Andes (50 km) or Ground (upward ’s)

Full mixing GZK ‘s !!!

(Tyler, A.O., Sigl, ‘01)

The Telescope Array