Neutrinos as probes of ultra-high energy astrophysical phenomena - - PowerPoint PPT Presentation

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

(1 particle per m2-second)

Knee

(1 particle per m2-year)

• Ankle

(1 particle per km2-year)

Energy (eV) Flux (m2 sr s GeV)-1

109 1011 1013 1015 1017 1019 1021 104

• 102
• 10-1

10-4 10-7 10-10 10-13 10-16 10-19 10-22 10-25 10-28

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

shock

V E E E E E E E

θ

V V

1 1 1 1 2 2 2 1

θ2

p p s 2 4

~ 10 E v E c β β

−

∆ = ≤

1

~ 10 E v E c β β

−

∆ = ≤

Hillas Plot

What 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 E18max=βsZBR

Auger sky map

• At energies > 6 X 1019 eV can get

indications of origin (why not at 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 + γ give pions

which give neutrinos

• eg. pγ ∆+ π+ n/π0 p

– π+ µ+ νµ e+ νe νµ νµ – π0 γ γ (Eγ~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 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
• bservations

– 050502B X-ray spike after burst, indications of multiple explosions

Fireball Model

Radiation dominated soup of leptons and photons implied by high optical depth Radiation pressure drives relativistic expansion of material outward

• M. Aloy et al. ApJL2000

Inner Engine Relativistic Wind External Shock Afterglow Internal Shocks γ-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 γ–ray emission produced by dissipation of fireball kinetic energy in internal shocks - supported by microstucture

Burst spectrum

b b

d dn

γ γ γ γ β γ α γ γ γ γ

ε ε ε ε ε ε ε ε > <      ∝ for for

GRB1122

ε εγ

γα α

εγ

b = 149.5 ± 2.1 keV

α = -0.968 ± 0.022 β = -2.427 ± 0.07 ε εγ

γβ β

ε εγ

γb b

Band et al., ApJ 413 (1993)

Burst spectrum

b b

d dn

γ γ γ γ β γ α γ γ γ γ

ε ε ε ε ε ε ε ε > <      ∝ for for

ε εγ

γα α

εγ

b = 100 – 300 keV

α ~ - 1 β ~ -2 ε εγ

γβ β

ε εγ

γb b

Synchrotron radiation from accelerated electrons Inverse Compton scattering or cooling of electrons at high energies

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

Neutrino production

• p + p or p + γ give pions

which give neutrinos

• eg. pγ ∆+ π+ n/π0 p

– π+ µ+ νµ e+ νe νµ νµ – π0 γ γ (Eγ~TeV)

Example of neutrino spectrum

1

~

−

∝ ⇒ ∝

ν γ γ ν γ

E E const E E E Ep

b b

E E E E dE dN E

ν ν ν ν α ν β ν ν ν ν

ε ε > <    ∝

− − − −

for for

1 1 2

• 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 ν Spectrum (II)

log(Eν /GeV) Φ Eν2 /(GeV (sr s cm2)-1) 10

• 11

10

• 10

10

• 9

10

• 8

2 3 4 5 6 7 8 9

b ν

ε

s ν

ε

'

ν

A

αν βν−2 βν

GRB ν Spectrum (III)

4 1 2 1 / ] [ ] ~ , [

min min

⋅ ⋅ = ⋅ = ∝

∫

e E E tot tot

f f x F x dE E dE dn E keV E

π γ ν ν ν ν

ν γ

fπ: fraction of proton energy going into pions

fe: fraction of electron

to proton total energy

50% charged pions, 25% per particle

ax

Neutrino production

• p + p or p + γ give pions

which give neutrinos

• eg. pγ ∆+ π+ n/π0 p

– π+ µ+ νµ e+ νe νµ νµ – π0 γ γ (Eγ~TeV)

Animation generated with povray

up to 10 MeV 10-40 MeV GeV – 10sTeV

Neutrino sources

• J. Becker
• Phys. Rep.

458

HE Neutrino probes of fundamental physics

Other neutrino detectors in proportion

Super Kamiokande SNO

AMANDA, RICE, IceCube, ANITA ANTARES NEMO NESTOR KM3NET Lake Baikal DUMAND

Neutrino telescopes around the globe

Topological Flavour Identification

• νµ produce long µ tracks
• Angular resolution ~ 10
• νe CC, νx NC cause showers
• ~ point sources ->’cascades’
• Good energy resolution
• ντ ‘double bang events
• Other ντ topologies under study

Muon – IC 40 data 16 PeV ντ simulation νe (cascade) simulation

Neutrino-nucleon cross-section

Earth becomes opaque for νe and νµ

note: angle from nadir

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

Astrophysical neutrinos caught

N e u t r i n

• s