Neutrinos as probes of ultra-high energy

astrophysical phenomena

Jenni Adams,

University of Canterbury,

New Zealand

up to 10 MeV

10-40 MeV

GeV – 10sTeV

Neutrino sources

J. Becker Phys. Rep. 458

How do we know there are high energy astrophysical phenomena?• Observe high energy particles

• Observe radiation that is indicative of high energy processes

• There might be hidden sources…

Cosmic messengers

Astroparticle physics

High energy photon astrophysics }astroparticle physics

Neutrino astrophysics

Cosmic ray astrophysics

Origin of the ultra-high energy cosmic rays?

?

How do we accelerate a particle?• Fermi Acceleration

How do we accelerate a tennis ball?

• Not with a steady tennis racket!

Need a moving racket

Back to particles…

ball ↔ charged particle

racket ↔ magnetic mirror

Fermi Acceleration•2nd Order:randomly distributed magnetic mirrors

slow and inefficient

•1st Order:acceleration in strong shock waves

2 4~ 10E v

E c

1~ 10E v

E c

Hillas PlotWhat condition is used to estimate the maximum energy which can be obtained from a given site?

The gyroradius is less than the linear size of the accelerator

Auger sky map• At energies > 6 X 1019 eV can get indications

of origin (why not a lower energies?)

• significance reduced in larger data set…?

How do we know there are high energy astrophysical phenomena?• Observe high energy particles

• Observe radiation that is indicative of high energy processes

• There might be hidden sources…

Non-thermal radiation – what do we mean by non-thermal?

Nature’s accelerators

Information from Gamma-Rays• Lots of sources identified

• Morphology of galactic sources resolved

• but most sources can be described by leptonic models as well as hadronic

Source of the highest energy cosmic rays

Why detect neutrinos?

Neutrino production• p + p or p + give pions

which give neutrinos

eg. p + + n/0 p– + + e+ e

– 0 (E~TeV)

Animation generated with povray

Why detect neutrinos?

Figure: Wolfgang Wagner, PhD thesis

Krawczynski et al., ApJ 601 (2004)

BL Lac Object

Short, intense, eruptions of high energy photons, with afterglow detected in X-ray to radio

Isotropic distribution in the sky

Bimodal distribution of burst times

Non-thermal photon spectrum

Energy output of 1051 erg to 1054 erg

What can you tell us about GRBs?

Accidentally discovered by the military Vela satellites in the late 1960’s

Progenitors• Long duration bursts result from collapse of

massive star to black hole– GRB030329 observed by HETE II linked to type

1C Supernova– Long duration bursts in galaxies with young

massive stars

• Short duration bursts result from collision of some combination of black holes and neutron stars– GRB050509B observed by Swift with limited

afterglow– Appears to have occurred near a galaxy with old

stars

• Theories may be rewritten by Swift observations– 050502B X-ray spike after burst, indications of

multiple explosions

Fireball ModelRadiation dominated soup of leptons and photons implied by high optical depth

Radiation pressure drives relativistic expansion of material outward

M. Aloy et al. ApJL2000

InnerEngine

Relativistic Wind

ExternalShock

Afterglow

InternalShocks

-rays

But observed spectrum is non-thermal and significant energy is expected to be transferred to the baryonic content in the wind

Shock fronts

Afterglow produced in external shocks – softened spectrum due to decreasing Lorentz factor

Prompt –ray emission produced by dissipation of fireball kinetic energy in internal shocks - supported by microstucture

Burst spectrum

b

b

d

dn

for

for

GRB1122

b = 149.5 ± 2.1 keV

= -0.968 ± 0.022

= -2.427 ± 0.07

bb

Band et al., ApJ 413 (1993)

Burst spectrum b

b

d

dn

for

for

b = 100 – 300 keV

~ - 1 ~ -2

bb

Synchrotron radiation from

accelerated electrons

Inverse Compton scattering

Example of neutrino spectrum for high energy astrophysical object – GRB Spectrum

Example of neutrino spectrum

1~ EEconstEEEEp

b

b

E

E

E

E

dE

dNE

for

for 1

12

• Highest energy pions lose energy via synchrotron emission before decaying reducing the energy of the decay neutrinos

• Effect becomes important when the pion lifetime is comparable to the synchrotron loss time

• Neutrino spectrum steepens by a power of

two after this second break energy

GRB Spectrum (II)

b

s

'A

GRB Spectrum (III)

4

1

2

1/

][]~,[min

min

e

E

E

tottot

ffx

FxdEEdE

dn

EkeVE

f: fraction of proton energy going into pionsfe: fraction of electron to proton total energycharged

pions per particle

ax

Neutrino production• p + p or p + give pions

which give neutrinos

eg. p + + n/0 p– + + e+ e

– 0 (E~TeV)

Animation generated with povray

IceCube and fundamental physics

up to 10 MeV

10-40 MeV

GeV – 10sTeV

Neutrino sources

J. Becker Phys. Rep. 458

Other neutrino detectors

in proportion

Super Kamiokande SNO

AMANDA, RICE, IceCube, ANITA

ANTARESNEMONESTORKM3NET

Lake Baikal

DUMAND

Neutrino telescopes around the globe

Topological Flavour Identification produce long tracks Angular resolution ~ 10

e CC, x NC cause showers ~ point sources ->’cascades’

Good energy resolution ‘double bang events

Other topologies under study

Muon – IC 40 data

PeV simulatione (cascade) simulation

Neutrino-nucleon cross-section

Earth becomes opaque for eand

Coming to a cinema (conference, journal) near you soon…

Astrophysical neutrinos

caught

Neutrinos