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

Neutrino sources 10-40 MeV GeV – 10sTeV up to 10 MeV 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 Neutrino astrophysics High energy photon astrophysics } astroparticle physics Cosmic ray astrophysics

Origin of the ultra-high energy cosmic rays? 10 4 � Flux (m 2 sr s GeV) -1 � 10 2 � � (1 particle per m 2 -second) 10 -1 10 -4 10 -7 Knee � 10 -10 (1 particle per m 2 -year) 10 -13 10 -16 10 -19 ? 10 -22 Ankle � � 10 -25 (1 particle per km 2 -year) 10 -28 10 9 10 11 10 13 10 15 10 17 10 19 10 21 Energy (eV)

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 •2 nd Order: randomly distributed magnetic mirrors ∆ E v 2 4 − ~ β β = ≤ 10 E c slow and inefficient •1 st Order: E 1 E E 1 1 E acceleration in strong shock waves 1 θ 1 V V p s ∆ E v 1 − ~ β β = ≤ 10 E 2 θ 2 E c E V p E 2 2 shock

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 E 18max = β s ZBR

Auger sky map • At energies > 6 X 10 19 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

Why detect neutrinos? Source of the highest energy cosmic rays

Animation generated with povray Neutrino production • p + p or p + γ give pions which give neutrinos eg. p γ � ∆ + � π + n/ π 0 p – π + � µ + ν µ � e + ν e ν µ ν µ – π 0 � γ γ (E γ ~TeV)

Why detect neutrinos? Figure: Wolfgang Wagner, PhD thesis

BL Lac Object Krawczynski et al., ApJ 601 (2004)

Accidentally discovered by the military = Vela satellites in the late 1960’s 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 10 51 erg to 10 54 erg

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 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

But observed spectrum is non-thermal and significant energy is expected to be transferred to the baryonic content in the wind Afterglow γ -rays Internal Relativistic Inner External Wind Shocks Engine Shock

Shock fronts Prompt γ –ray emission produced by dissipation of fireball kinetic energy in internal shocks - supported by microstucture Afterglow produced in external shocks – softened spectrum due to decreasing Lorentz factor

Burst spectrum Band et al., ApJ 413 (1993) α b  < dn for  ε ε ε ε γα α γ γ γ γ γ ε γ ε ∝  β b >  d for ε ε ε ε  γ γ γ γ β γβ α = -0.968 ± 0.022 ε γ ε β = -2.427 ± 0.07 b = 149.5 ± 2.1 keV ε γ γ b b ε γ ε GRB1122

α b  < dn for  ε Burst spectrum ε ε ε γ γ γ γ γ ∝  β b >  d for ε ε ε ε  γ γ γ γ Inverse Compton γα α ε γ ε scattering or Synchrotron cooling of radiation from electrons at high accelerated energies β γβ ε γ ε electrons α ~ - 1 β ~ -2 b = 100 – 300 keV ε γ γ b b ε γ ε

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. p γ � ∆ + � π + n/ π 0 p – π + � µ + ν µ � e + ν e ν µ ν µ – π 0 � γ γ (E γ ~TeV)

Example of neutrino spectrum 1 − E p E E E const E E ∝ ⇒ ∝ ~ γ ν γ γ ν 2 β 1 b  − − < E for E E dN ε ν ν ν ν ν ∝  α 1 b − − > dE E for E ε  ν ν ν ν

GRB ν Spectrum (II) • 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

s b ε ε -8 ν ν Φ E ν 2 /(GeV (sr s cm 2 ) -1 ) 10 A ' β ν ν -9 10 α ν β ν −2 -10 10 -11 10 2 3 4 5 6 7 8 9 log(E ν /GeV)

GRB ν Spectrum (III) E [ , ~ keV ] E [ ] γ ∝ ν tot tot E min ax dn ν E dE x F ∫ = ⋅ ν ν γ dE E ν min 1 1 x f / f = ⋅ ⋅ e π 2 4 50% charged pions , 25% per particle f e : fraction of electron to proton total energy f π : fraction of proton energy going into pions

Animation generated with povray Neutrino production • p + p or p + γ give pions which give neutrinos eg. p γ � ∆ + � π + n/ π 0 p – π + � µ + ν µ � e + ν e ν µ ν µ – π 0 � γ γ (E γ ~TeV)

Neutrino sources 10-40 MeV GeV – 10sTeV up to 10 MeV J. Becker Phys. Rep. 458

HE Neutrino probes of fundamental physics

Other neutrino detectors in proportion Super Kamiokande SNO

Neutrino telescopes around the globe Lake Baikal ANTARES NEMO NESTOR KM3NET DUMAND AMANDA, RICE, IceCube, ANITA

Muon – IC 40 data Topological Flavour Identification • ν µ produce long µ tracks • Angular resolution ~ 1 0 • ν e CC, ν x NC cause showers • ~ point sources ->’cascades’ • Good energy resolution • ν τ ‘double bang events • Other ν τ topologies under study ν e (cascade) simulation 16 PeV ν τ simulation

Neutrino-nucleon cross-section

Earth becomes opaque for ν e and ν µ note: angle from nadir

Coming to a cinema (conference, journal) near you soon… o s r i n e u t N Astrophysical neutrinos caught