casc lim IC a25 · Introduction Outline of the talk 1 Introduction 2 IceCube events properties...

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High-Energy Neutrinos

Michael Kachelrieß

NTNU, Trondheim

Introduction

Outline of the talk

1 Introduction

2 IceCube events

◮ properties

◮ implications

3 Astrophysical sources

◮ point sources versus diffuse flux

◮ Galactic sources versus extragalactic

4 PeV dark matter

5 Summary

Michael Kachelrieß (NTNU Trondheim) High-Energy Neutrinos Oslo 2014 2 / 33

Introduction

Outline of the talk

1 Introduction

2 IceCube events

◮ properties

◮ implications

◮ or better speculations. . .

3 Astrophysical sources

◮ point sources versus diffuse flux

◮ Galactic sources versus extragalactic

4 PeV dark matter

5 Summary


Introduction

1912: Victor Hess discovers cosmic rays

-10

0

20

40

60

80

1 2 3 4 5 6 7 8 9

exce

ss io

niza

tion

altitude/1000m

Hess’ and Kolhoerster’s results:

“The results are most easily ex-plained by the assumption that ra-diation with very high penetratingpower enters the atmosphere fromabove; the Sun can hardly be con-sidered as the source.”


Introduction

1912: Victor Hess discovers cosmic rays

-10

0

20

40

60

80

1 2 3 4 5 6 7 8 9

exce

ss io

niza

tion

altitude/1000m

Hess’ and Kolhoerster’s results:

Two main questions

what are they?

what are their sources?


Introduction

What do we know 100 years later?

sola

rm

odula

tion

→

LHC ⇑


Introduction

What do we know 100 years later?

sola

rm

odula

tion

→

LHC ⇑

Basic information:

energy density ρcr ∼ 0.8eV/cm3

non-thermal power-law spectrum, dN/dE ∝ 1/Eα

nuclear composition, few e−, γ

isotropic flux for E <∼ 1018 eV


Introduction

The CR–γ–ν connection:

HE neutrinos and photons are unavoidable byproducts of HECRs

astrophysical models, cosmogenic flux:◮ ratio Iν/Ip determined by nuclear composition of UHECRs and source

evolution◮ ratio Iν/Iγ determined by isospin


Introduction





astrophysical models, direct flux:◮ model dependent fluxes: ∝ target density, . . .


Introduction






top-down DM models:◮ large fluxes with Iν ≫ Ip

◮ ratio Iν/Ip fixed by fragmentation


Introduction






top-down DM models:◮ large fluxes with Iν ≫ Ip

◮ ratio Iν/Ip fixed by fragmentation

prizes to win:◮ astronomy above 100 TeV◮ identification of CR sources◮ determination galactic–extragalactic transition of CRs◮ test/discover new particle physics


Introduction

What is the bonus of HE neutrino astronomy?astronomy with VHE photons restricted to few Mpc:

10

12

14

16

18

20

22

Gpc100Mpc10MpcMpc100kpc10kpckpc

log1

0(E

/eV

)

photon horizon γγ → e+e− CMB

IR

radio


Introduction

What is the bonus of HE neutrino astronomy?astronomy with VHE photons restricted to few Mpc:

10

12

14

16

18

20

22


log1

0(E

/eV

)


IR

radio

ambiguity: leptonic/hadronic origin


Introduction

HE neutrino astronomy vs UHECRs?

10

12

14

16

18

20

22


log1

0(E

/eV

)proton horizon


IR

Virgo ⇓


Introduction

HE neutrino astronomy vs UHECRs?

10

12

14

16

18

20

22


log1

0(E

/eV

)proton horizon


IR

Virgo ⇓

◮ large statistics of UHECRs, well-suited horizon scale

◮ but no conclusive evidence that qB is small enough


Introduction

What is the bonus of HE neutrino astronomy?Neutrino astronomy: small σνN

large λν but also “large” uncertainty 〈δϑ〉 >∼ 0.1◦ − 1◦


Introduction



small event numbers: ∼ 1/yr for PAO or ICECUBE

103

102

10

1

10-1

1022102110201019101810171016

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

WB

max

0.2

CR flux

⇒ identification of steady sources challenging


Introduction



small event numbers: ∼ 1/yr for PAO or ICECUBE

103

102

10

1

10-1

1022102110201019101810171016

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

WB

max

0.2

CR flux

⇒ identification of steady sources challenging

correlation with AGN flares, GRBs

diffuse flux detected first


Introduction

IceCube

[ ]


Introduction

IceCube:Top View

AMANDA

SPASE-2South Pole

Dome

Skiway

100 m

Grid North

IceCube

Counting House


Introduction

IceCube

80 Strings4800 PMT

1400 m

2400 m

AMANDA

South Pole

IceTop

Skiway


Introduction


Icecube events

Icecube: 2 events presented at Neutrino 20122 cascade events close to Emin = 1015 eV, bg = 0.14

Two events passed the selection criteria

8

Run119316-Event36556705 Jan 3rd 2012 NPE 9.628x104

Number of Optical Sensors 312

Run118545-Event63733662 August 9th 2011 NPE 6.9928x104

Number of Optical Sensors 354

CC/NC interactions in the detector

MC

2 events / 672.7 days - background (atm. m + conventional atm. n) expectation 0.14 events

preliminary p-value: 0.0094 (2.36s)


Icecube events

Icecube: prompt neutrino analysis [A. Schukraft, NOW2012 ]

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Icecube events

IceCube events: specifications for candidate sources

36 events with ∼ 14 bg: flukes are possible. . .


Icecube events



anisotropies◮ event cluster around GC◮ enhancement close to Galactic plane?


Icecube events

IceCube events: 2 years 28 events


Icecube events

IceCube events: 3 years 36 events


Icecube events

KS test for ansiotropy in RA

0

0.2

0.4

0.6

0.8

1

0 50 100 150 200 250 300 350

RA

C(event)isotropic


Icecube events

KS test for ansiotropy in RA

0

0.2

0.4

0.6

0.8

1

0 50 100 150 200 250 300 350

RA

C(event)isotropic

p = 20% for 2 yr, p = 8% for 3 yr data set


Icecube events



anisotropies◮ event cluster around GC◮ enhancement close to Galactic plane gone?


Icecube events




flux is large, close to◮ Waxman-Bahcall estimate◮ cascade limit: slope “is steepening”, α ∼ 2.3 − 2.5, conflict?


Icecube events





CR energies Ep ∼ 20Eν ⇒ up to few×1016 eV,◮ high for Galactic CRs◮ lowish for cosmogenic, AGN, GRB


Icecube events





CR energies Ep ∼ 20Eν ⇒ up to few×1016 eV,◮ high for Galactic CRs◮ lowish for cosmogenic, AGN, GRB

initial flavor ratio consistent with 1:1:1 ?


Icecube events

Flavour ratioratio R = Nsh/Ntr ∼ (Ne + Nτ )/Nµ ∼ 21/7 consistent with 1:1:1including atm. bg. favors (weakly) 1:0:0 at source [Mena, Palomares, Vincent ’14 ]


Astrophysical sources

Sources of high-energy neutrinos

Galactic sources:

Galactic plane and bulge

SNR

hypernova, GRB

micro-quasar, . . .

Extragalactic sources:

diffuse flux from normal/starburst galaxies

cosmogenic neutrinos

diffuse flux from AGN

GRB

single AGN, . . .

Dark matter decays, topological defects


Astrophysical sources CR sea interactions in bulge and plane

Neutrinos from Galactic Sea CRs: “Hillas” X = 30 g/cm2

0.01

0.1

1

10

100

1011 1012 1013 1014 1015 1016 1017 1018

E2.

6 I(E

) [G

eV1.

6 m-2

sr-1

s-1

]

E/eV

pHe

CO

Fetotal

[MK, S.Ostapchenko ’14 ]



Neutrinos from Galactic Sea CRs: “escape” X = 30 g/cm2

0.01

0.1

1

10

100

1000

1011 1012 1013 1014 1015 1016 1017 1018

E2.

6 I(E

) [G

eV1.

6 m-2

sr-1

s-1

]

E/eV

pHe

CO

Fetotal




Neutrinos from Galactic Sea CRs: X = 30 g/cm2

0.01

0.1

1

10

100

1000

1011 1012 1013 1014 1015 1016 1017 1018

E2.

6 I(E

) [G

eV1.

6 m-2

sr-1

s-1

]

E/eV

HillasPolygonato

Escape




Neutrinos from Galactic Sea CRs: X = 30 g/cm2

0.01

0.1

1

10

100

1000

1011 1012 1013 1014 1015 1016 1017 1018

E2.

6 I(E

) [G

eV1.

6 m-2

sr-1

s-1

]

E/eV

HillasPolygonato

Escape

model dependence impacts background in IceCube



Neutrinos from Galactic Sea CRs

gives negligible contribution to IceCube signal

τpp is too small even towards GC

gas is concentrated as n(z) ∼ n0 exp[−(z|/z12)2] with z12 ∼ 0.2 kpc

results apply also to other normal galaxies as starburst galaxies:








magnetic fields factor 100 higher:








magnetic fields factor 100 higher:

if knee is caused by◮ diffusion: Ecr ∼ B, neutrino knee at few ×1016 eV

◮ source: Emax ∼ BCR, neutrino knee at few ×1014 eV


Astrophysical sources Galactic point sources

Galactic sources

at low energies:

◮ many sources, large confinement times



Galactic sources

at low energies:


⇒ average CR sea plus few recent sources



Galactic sources

at low energies:



close to the knee:

◮ CRs in PeV range spread fast

◮ few extreme sources



Galactic sources

at low energies:



close to the knee:

◮ CRs in PeV range spread fast

◮ few extreme sources

⇒ inhomogenous CR sea, extended sources

⇒ no clear distinction between point sourcesvs. Galactic bulge + plane cases



Point source in gamma-ray

source HESS J1825-137 [Neronov, Semikoz, Tchernin ’13 ]

0.00100

0.00150

0.00200

0.00250

0.00300

0.00350

0.00400

0.00450

0.00500

0.00550

0.00600

180.000225.000270.000315.000 0.00045.00090.000135.000

-90.000

-60.000

-30.000

0.00

0

30.000

60.000

90.000

Kookaburra region

HESS J1632 region

Galactic Center

HESS J1825 region

Cygnus region

Vela region

Crab



Gamma-ray point sourcesflux from HESS J1825-137, GC and GP



(Isotropic) photon limits

101 102 103 104

Eγ [TeV]

10−10

10−9

10−8

10−7

10−6

10−5

10−4

E2J

γ[G

eVcm

−2

s−1

sr−

1]

8.5kpc

20kpc

30kpc

GRAPES-3

UMC

HEGRA

EAS-TOP

IC-40 (γ)

KASCADE

GAMMA

CASA-MIA

[Ahlers, Murase ’13 ]


Astrophysical sources Diffuse extragalactic flux

Diffuse ν flux from normal and starburst galaxies

103

105

107

109

1011

10−9

10−8

10−7

10−6

10−5

Eν [GeV]

E2 ν Φ

ν [G

eV/c

m2 s

sr]

0.1 km2

1 km2

WB Bound

Star Bursts

AMANDA( νµ); Baikal(νe)

Atmospheric→← GZK

[Loeb, Waxman ’06 ]


Astrophysical sources Diffuse extragalactic flux

Diffuse ν flux from normal and starburst galaxies

103

105

107

109

1011

10−9

10−8

10−7

10−6

10−5

Eν [GeV]

E2 ν Φ

ν [G

eV/c

m2 s

sr]

0.1 km2

1 km2

WB Bound

Star Bursts

AMANDA( νµ); Baikal(νe)

Atmospheric→← GZK

[Loeb, Waxman ’06 ]

too optimistic?◮ fraction of starbust galaxies?◮ all calorimetric?


Astrophysical sources Cosmogenic neutrinos

Reminder: The photon horizon

10

12

14

16

18

20

22


log1

0(E

/eV

)


IR

radio


Astrophysical sources Cascade spectrum

Development of the elmag. cascade:



Development of the elmag. cascade:

analytical estimate: [Strong ’74, Berezinsky, Smirnov ’75 ]

Jγ(E) =

K(E/εX)−3/2 at E ≤ εX

K(E/εX)−2 at εX ≤ E ≤ εa

0 at E > εa

three regimes:◮ Thomson cooling:

Eγ =4

3

εbbE2e

m2e

≈ 100 MeV

(

Ee

1TeV

)2

◮ plateau region: ICS Eγ ∼ Ee

◮ above pair-creation threshold smin = 4Eγεbb = 4m2e:

flux exponentially suppressed



Fermi limit for cosmogenic neutrinos: [Berezinsky et al. ’10 ]

1016 1017 1018 1019 1020 1021 102210-1

100

101

102

103

104

105

106

1021

1020

IceCube 5yr tilted

2.0

RICE

Auger diff.

E-2 cascade

ANITA

E2 J(

E), e

Vcm

-2s-1

sr-1

E, eV

ANITA-liteAuger

2.6

nadirJEM-EUSOBAIKAL

e =

1022

m=3



Cascade limit: α = 2.1

1

10

100

1000

10000

1e+10 1e+11 1e+12 1e+13 1e+14 1e+15 1e+16 1e+17

E2 J

(E)

[eV

/cm

2 s s

r]

E/eV

gammanu

Fermi EGRB




1

10

100

1000

10000

1e+10 1e+11 1e+12 1e+13 1e+14 1e+15 1e+16 1e+17

E2 J

(E)

[eV

/cm

2 s s

r]

E/eV

gammanu

Fermi EGRB



IceCube limit on GRBs

215 optically detected GRBs stacked



IceCube limit on GRBs

215 optically detected GRBs stacked

10

4

10

5

10

6

10

7

Neutrino Energy (GeV)

10

-9

10

-8

E

2

Φ

ν

(GeV cm

−2

s

−1

sr

−1

)

Waxman & BahcallIC40 limitIC40 Guetta et al.IC40+59 Combined limitIC40+59 Guetta et al.

10

-1

10

0

E

2

F

ν

(GeV cm

−2

)


PeV dark matter

PeV dark matterre-incarnation of SHDM idea for AGASA excess:

non-hermal DM

avoids cascacde limit

Galactic anisotropy

some option to move initial flavor ration 1 : 2 : 0 towards 1 : 0 : 0


PeV dark matter

PeV dark matter

DM ® ΝeΝ e H15%L, bb H85%L

DM ® ΝeΝ e H12%L, cc H88%L

DM ® e-e+ H40%L, qq H60%L

1 10 102 103

10-11

10-10

EΝ HTeVL

EΝ2 dJ�d

EΝHT

eVcm-

2s-

1sr-

1 L

[Esmaili, Serpico ’13 ]


PeV dark matter

PeV dark matter

102 103

0.1

1

10

EΝ HTeVL

even

ts�b

in

DM ® ΝΝ , qqE-2 spec.

data

[Esmaili, Serpico ’13 ]


PeV dark matter

Summary

1 excess towards GC, consistent (?) with γ-ray data

⇒ partly Galactic origin

2 no enhancement towards Galactic plane:

◮ gas too narrow, flux too low

3 some tension with (Northern) γ-ray limits

4 extragalactic:◮ dominant isotropic component◮ diffuse, difficult to identify◮ spectrum α = −2.45: cascade limit?

5 PeV dark matter: angular distibution follows DM profile


casc lim IC a25 · Introduction Outline of the talk 1 Introduction 2 IceCube events properties...

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