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