Top-Down Models and UHECRs - NTNUweb.phys.ntnu.no/~mika/topdown.pdf · Bottom-up versus top-down...

Top-Down Models and UHECRs

Michael Kachelrieß

NTNU, Trondheim

Bottom-up versus top-down models

Bottom-up models

acceleration in electromagnetic fields

⇒ charged particles: protons, nuclei, electrons

photons and neutrinos as secondaries

Rencontres de Blois 2008 Michael Kachelrieß Top-Down Models

Bottom-up versus top-down models

Bottom-up models

acceleration in electromagnetic fields

⇒ charged particles: protons, nuclei, electrons

photons and neutrinos as secondaries

Top-down models

relics from early universe ↔ DM

non-thermal or thermalpoint particle or non-perturbative solutionsstable or decaying

fragmentation products: mainly photons, neutrinos


Dark matter candidates

SHDM

SM neutrinos

gravitino

axion

axino

WIMP

−40

−35

−30

−25

−20

−15

−10

−5

0

−18−15−12−9 −6 −3 0 3 6 9 12 15 18

log(m/GeV)

log(

σ/p

bar

n)


The standard candidate: WIMP

inflation suggested Ω = 1, CMB shows that Ω ≈ 1BBN constrains baryon content, Ωbh

2 = 0.019±0.001LSS requires that DM is dissipation-less and “cold”thermal production of CDM,

ΩXh2 ∼3×10−27cm3/s

〈σv〉

suggests weakly interacting DM particle with mass m ∼ mZ


The standard candidate: WIMP

inflation suggested Ω = 1, CMB shows that Ω ≈ 1BBN constrains baryon content, Ωbh

2 = 0.019±0.001LSS requires that DM is dissipation-less and “cold”thermal production of CDM,

ΩXh2 ∼3×10−27cm3/s

〈σv〉

suggests weakly interacting DM particle with mass m ∼ mZ

unitarity limit: m <∼ 100 TeV


Status of neutralino DM after LEPII:

100 200 300 400 500 600 700 800 900 10000

100

200

300

400

500

600

700

800

100 200 300 400 500 600 700 800 900 10000

100

200

300

400

500

600

700

800

mh = 114 GeV

m0

(GeV

)

m1/2 (GeV)

tan β = 10 , µ > 0

mχ± = 103.5 GeV


Status of neutralino DM after LEPII:

100 1000 15000

1000

2000

3000

3500

100 1000 15000

1000

2000

3000

3500

mh = 114 GeVm0

(GeV

)

m1/2 (GeV)

mt = 171 GeV , tan β = 10 , µ > 0


Indirect detection claims:

Signal fromχχ annihilations in the diffuse extragalactic photon background:


Indirect detection claims: [Elsasser, Mannheim ’04 ]

Signal from χχ annihilations in the diffuse extragalacticphoton background:

0,1 1 10 100 100010-7

10-6

E

2 x G

amm

a R

ay In

tens

ity /

(G

eV c

m-2 s

-1 s

r-1)

Observed Gamma Ray Energy / GeV

EGRET

mχ = 520 GeV

<σv>χ = 3.1 x 10-25 cm3s-1

Dark Matter Scenario (Total)χ2/ν =0.74

α = -2.33

Straw Person's Blazar Model:

χ2/ν =1.05

Salamon & Stecker Blazar Model

µ = 978GeVm2 = -1035GeV

mA = 1036GeV

tan β = 6.6mS = 1814GeV

At = 0.88

Ab = -2.10

Ωh2 = 0.1


Indirect detection claims:

Signal from χχ annihilations in the diffuse extragalacticphoton background:

0,1 1 10 100 100010-7

10-6

E

2 x G

amm

a R

ay In

tens

ity /

(G

eV c

m-2 s

-1 s

r-1)

Observed Gamma Ray Energy / GeV

EGRET

mχ = 520 GeV

<σv>χ = 3.1 x 10-25 cm3s-1

Dark Matter Scenario (Total)χ2/ν =0.74

α = -2.33

Straw Person's Blazar Model:

χ2/ν =1.05

Salamon & Stecker Blazar Model

µ = 978GeVm2 = -1035GeV

mA = 1036GeV

tan β = 6.6mS = 1814GeV

At = 0.88

Ab = -2.10

Ωh2 = 0.1

problem:

search for small excess on top of “astrophysical background”


Reminder: GZK puzzle as motivation for top-down models

no obvious counter-parts for 1020eV events




acceleration beyond 1020eV difficult





AGASA excess





AGASA excess

misinterpretation of GZK suppression as GZK cutoff


Modification factor: [Berezinsky, Gazizov, Grigorieva ’03 ]

1017 1018 1019 1020 1021

10-2

10-1

100

ηtotal

2

1 η

ee

2

1

1: γg=2.7

2: γg=2.0

mod

ifica

tion

fact

or

E, eVRencontres de Blois 2008 Michael Kachelrieß Top-Down Models

Modification factor: AGASA excess

1017 1018 1019 1020 1021

10-2

10-1

100

Akeno-AGASA

ηtotal

ηee

γg=2.7

mod

ifica

tion

fact

or


Modification factor: Nuclei

1017 1018 1019 1020 102110-2

10-1

100

ηtotal

ηee

FeAl

red shift

Hep

γg=2.7

m

odifi

catio

n fa

ctor


GZK suppression – dependence on ns

10-2

1

102

1018 1019 1020 1021

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

AGASA

z=0

50 Mpc

z=0.03

z=0.1

[MK, Semikoz and Tortola ’03 ]


GZK suppression – dependence on ns

10-2

1

102

1017 1018 1019 1020 1021

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

HiRes

z=0

50 Mpc

z=0.03

z=0.1

[MK, Semikoz and Tortola ’03 ]


Top-Down Models

UHECR primaries are produced by decays of supermassive particleX with MX >∼ 1012 GeV.

topological defects: monopoles, strings, . . .[Hill ’83; Ostriker, Thompson, Witten ’86 ]

superheavy metastable particles[Berezinsky, MK, Vilenkin ’97; Kuzmin, Rubakov ’97 ]

Advantages:

no acceleration problem

no visible sources

if X ∈ CDM, no GZK-cutoff

theoretically motivated; testable predictions


Gravitational creation of superheavy matter

Small fluctuations of field Φ obey

φk +[

k2 +m2eff(τ)

]

φk = 0




φk +[

k2 +m2eff(τ)

]

φk = 0

If meff is time dependent, vacuum fluctuations will betransformed into real particles.




φk +[

k2 +m2eff(τ)

]

φk = 0


⇒ expansion of Universe,

m2eff = M2a2 +(6ξ−1)

a′′

a

leads to particle production




φk +[

k2 +m2eff(τ)

]

φk = 0


⇒ expansion of Universe,

m2eff = M2a2 +(6ξ−1)

a′′

a

leads to particle production

In inflationary cosmology

ΩXh2 ∼

(

MX

1012GeV

)2TRH

109GeV

dependent only on cosmology, for MX <∼ HI

[Kuzmin, Tkachev ’98; Chung, Kolb, Riotto ’98 ]


Gravitational creation of superheavy matter:


Properties of superheavy matter:

was never in thermal equlibrium:

⇒ unitarity limit M <∼ 30 TeV does not apply





can be strongly interacting and dissipation-less:

small relative energy transfer dE/(Edt) per time requires:either small σ or

small energy transfer y

⇒ any DM particle with mX >∼ 10 TeV is dissipation-less





can be strongly interacting and dissipation-less:

small relative energy transfer dE/(Edt) per time requires:either small σ or

small energy transfer y

⇒ any DM particle with mX >∼ 10 TeV is dissipation-less

lifetime:

metastable or stable due to some (gauged) R symmetry


Detection of superheavy matter:

direct detection: density 1/MX , recoil energy is constant⇒ large σXN required

-32

-30

-28

-26

-24

-22

-20

4 6 8 10 12 14 16log Mχ (GeV)

log

σ (c

m2 )



indirect detection via neutrinos from the Sun:signal should compete with usual fluxes⇒ 〈σv〉 ∼ 10−26 cm2 needed



UHECR above the GZK cutoff via nucleon, photon secondaries

E3J(E

)/m

−2s−

1eV

2

E/eV

1e+23

1e+24

1e+25

1e+26

1e+18 1e+19 1e+20 1e+21


Lifetime:

stable: annihilation gives too small flux

decay: too fast?For MX >∼ 1010 GeV even gravitational interactions result incosmological short lifetimes, τX ≪ t0.

global symmetry broken by wormhole effects, τX ∝ exp(S)

symmetry broken by instanton effects,τX ∝ exp(−4π2/g2)

discrete symmetries forbid operators with d < 9

crypton or fractionally charged and confined particle ofsuperstring theories


Fragmentation of heavy particles

consider Bremsstrahlung, X → f fV :

soft and collinear singularities generate terms ln2(m2V /m2

X ) form2

X ≫ m2V ⇒ compensate the small couplings g2,

g2 ln2(m2X/m2

V ) ≈ 1





X ) form2


g2 ln2(m2X/m2

V ) ≈ 1

MX >∼ 106 GeV, ⇒ naive perturbation theory breaks down:electroweak and SUSY sector have a QCD-like behavior(“jets”)

[Berezinsky, MK ’98, Berezinsky, MK, Ostapchenko ’02 ]





X ) form2


g2 ln2(m2X/m2

V ) ≈ 1

MX >∼ 106 GeV, ⇒ naive perturbation theory breaks down:electroweak and SUSY sector have a QCD-like behavior(“jets”)

[Berezinsky, MK ’98, Berezinsky, MK, Ostapchenko ’02 ]

(modified) DGLAP description possible



XqL qL

g

g

g

qL

qL

1 TeV(SUSY

+ SU(2) ⊗ U(1)

breaking)

qq

gq

q

χ0

2

qL

χ0

1q

1 GeV(hadronization)

qL

B

qR

qR

qW

τ

a−

1

ρ−

π−

νµ

µ−νµ

νe

e−

π0 γ

γ

π0

γ

γντ

ντ

qq

g

gq

q

gq

q

n

p

e−

νe

π0

γ

γ


Signatures of SHDM decays

flat spectra dE/E 1.9 up to mX/2

E3J(E

)/m

−2s−

1eV

2

E/eV

1e+23

1e+24

1e+25

1e+26

1e+18 1e+19 1e+20 1e+21

[Aloisio, Berezinsky, MK, ’03 ]

⇒ SHDM dominates UHECR flux only above ∼ 8×1019 eV




composition:γ/p ≫ 1, large neutrino fluxes, no nucleiLSPs, if R parity conserved

x3D

i(x,M

X)

1016GeV

1014GeV

1e-10

1e-09

1e-08

1e-07

1e-06

1e-05

0.0001

0.001

0.01

1e-05 0.0001 0.001 0.01 0.1 1



Fig. 2.—The vs. relation for observed events (circles andr (1000) Em 0

squares). The solid line is a fit to data between 1019 and 1020 eV. The expected1 j bound for simulatedg-ray showers is indicated by the shaded region, and

Fig.

at a 95% CL by arrows. The different curves correspond to the predictionsfrom the following origin models: (Z-burst model ((dotted curve

UHECR spectrum above 10accelerated from lower energies is included by assuming anexpected spectrum consistent with the GZK prediction for the



flat spectra dE/E 1.9 up to mX/2composition:

1019 1020 10210.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

[33]

[32]

E (eV)




composition:

galactic anisotropy: [Dubovsky, Tinyakov ’98 ]

0 20 401

10

NFW

1020 eV 6x1019 eV 3x1019 eV 1019 ev


Topological defect models

+ “generic” in SUSY-GUTs+ produced during reheating

- typical density: one per horizon/correlation length- main energy loss low-energy radiation?


Topological defect models [Allen, Shellard ’06 ]

box 2ct

matterepoch

scalingregime



+ “generic” in SUSY-GUTs

+ produced during reheating

- typical density: one per horizon/correlation length

- main energy loss low-energy radiation?

favourable models for UHECRs:

monopole-antimonopole pairs

hybrid defects: cosmic necklaces



+ “generic” in SUSY-GUTs

+ produced during reheating

- typical density: one per horizon/correlation length

- main energy loss low-energy radiation?

favourable models for UHECRs:

monopole-antimonopole pairs

hybrid defects: cosmic necklaces

G → H ⊗U(1) → H ⊗Z2

monopoles M ∼ ηm/e connected by strings µs ∼ η2s

parameter r = M/(µd):r ≪ 1 normal string dynamicsr ≫ 1 non-rel. string network


Status of topological defect models – necklaces:

E3J(E

)/m

−2s−

1eV

2

E/eV

ν

p γ

p+γ

1e+22

1e+23

1e+24

1e+25

1e+26

1e+27

1e+18 1e+19 1e+20 1e+21 1e+22

[Aloisio, Berezinsky, MK, ’03 ]


Status of topological defect models – necklaces:

E3J(E

)/m

−2s−

1eV

2

E/eV

ν

p γ

p+γ

1e+22

1e+23

1e+24

1e+25

1e+26

1e+27

1e+18 1e+19 1e+20 1e+21 1e+22

⇒ shape of spectrum allows only sub-dominant contribution• UHE photon fraction reduced


Cosmic necklaces: [Blanco-Pillado, Olum ’07 ]


Idea of EGRET limit

all energy in γ and e± cascades down to GeV–TeV range, boundedby observations:

ωcas = femmX

Z t0

0dt (1+ z)−4 nX (t)

<∼ 2 ·10−6 eV/cm3


Elmag. cascades and EGRET limit:

1

102

104

108 1010 1012 1014 1016 1018 1020 1022

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

EGRET

1.8

0.2

1.8

0.2

1.8

0.2

γ νi

p

[Semikoz, Sigl ’03 ]


Summary

AGASA excess as main motivation for top-down models isgone

no positive evidence for superheavy dark matter from its twokey signatures:

photonsgalactic anisotropy

SHDM remains an interesting DM candidate

topological defects are generic prediction of (SUSY-) GUTs

should be searched for as subdominant sources of UHECR


Sensitivity of neutrino detectors

1

10

102

103

1012 1014 1016 1018 1020 1022

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

γ-ray bound

MPR bound

WB bound

atm ν

ICECUBE

NUTEL

EUSO

ANITA 30 days

TA

RICE

AUGER

AMANDA-II, ANTARES

BAIKAL


Sensitivity of neutrino detectors

1

10

102

103

1012 1014 1016 1018 1020 1022

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

γ-ray bound

MPR bound

WB bound

atm ν

ICECUBE

NUTEL

EUSO

ANITA 30 days

TA

RICE

AUGER

AMANDA-II, ANTARES

BAIKAL


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Top-Down Models and UHECRs - NTNUweb.phys.ntnu.no/~mika/topdown.pdf · Bottom-up versus top-down...

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