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Neutrino flavor ratios from cosmic accelerators on the Hillas plot
NOW 2010September 4-11, 2010Conca Specchiulla (Otranto, Lecce, Italy)
Walter WinterUniversität Würzburg
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Contents
Introduction Meson photoproduction Our model Flavor composition at source Hillas plot and parameter space scan Flavor ratios/flavor composition at detector Summary
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From Fermi shock acceleration to production
Example: Active galaxy(Halzen, Venice 2009)
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Often used: (1232)-resonance approximation
Limitations:- No - production; cannot predict / - ratio- High energy processes affect spectral shape- Low energy processes (t-channel) enhance charged pion production Charged pion production underestimated compared to production by
factor of > 2.4 (independent of input spectra!) Solutions:
SOPHIA: most accurate description of physicsMücke, Rachen, Engel, Protheroe, Stanev, 2000Limitations: Often slow, difficult to handle; helicity dep. muon decays!
Parameterizations based on SOPHIA Kelner, Aharonian, 2008
Fast, but no intermediate muons, pions (cooling cannot be included) Hümmer, Rüger, Spanier, Winter, 2010
Fast (~3000 x SOPHIA), including secondaries and accurate / - ratios; also individual contributions of different processes (allows for comparison with -resonance!)
Engine of the NeuCosmA („Neutrinos from Cosmic Accelerators“) software
Meson photoproduction
T=10 eV
from:Hümmer, Rüger, Spanier, Winter,
ApJ 721 (2010) 630
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NeuCosmA key ingredients What it can do so far:
Photohadronics based on SOPHIA(Hümmer, Rüger, Spanier, Winter, 2010)
Weak decays incl. helicity dependence of muons(Lipari, Lusignoli, Meloni, 2007)
Cooling and escape Potential applications:
Parameter space studies Flavor ratio predictions Time-dependent AGN simulations
etc. (photohadronics) Monte Carlo sampling of diffuse
fluxes Stacking analysis with measured
target photon fields Fits (need accurate description!) …
from: Hümmer, Rüger, Spanier, Winter, ApJ 721 (2010) 630
Kinematics ofweak decays: muon helicity!
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A self-consistent approach Target photon field typically:
Put in by hand (e.g. GRB stacking analysis) Thermal target photon field From synchrotron radiation of co-accelerated
electrons/positrons Requires few model parameters
(synchtrotron cooling dominated only overall normalization factor)
Purpose: describe wide parameter ranges with a simple model; no empirical relationships needed!
?
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Opticallythin
to neutrons
Model summary
Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010
Dashed arrow: Steady stateBalances injection with energy losses and escape
Q(E) [GeV-1 cm-3 s-1] per time frameN(E) [GeV-1 cm-3] steady spectrum
Injection Energy losses Escape
Dashed arrows: include cooling and escape
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A typical example
Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010
=2, B=103 G, R=109.6 km
Maximum energy: e, p Cooling: charged , , K
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A typical example (2)
Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010
=2, B=103 G, R=109.6 km
cooling break
cooling break
Pile-upeffect
Pile-up effect Flavor ratio!
Slope:/2
Synchrotroncooling Spectral
split
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The Hillas plot
Hillas (necessary) condition for highest energetic cosmic rays (: acc. eff.)
Protons, 1020 eV, =1:
We interpret R and B as parameters in source frame High source Lorentz factors
relax this condition!Hillas 1984; version adopted from M. Boratav
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Astrophysical neutrino sources producecertain flavor ratios of neutrinos (e::):
Pion beam source (1:2:0)Standard in generic models
Muon damped source (0:1:0)at high E: Muons loose energy before they decay
Muon beam source (1:1:0)Heavy flavor decays or muons pile up at lower energies
Neutron beam source (1:0:0)Neutrino production by photo-dissociationof heavy nuclei or neutron decays
At the source: Use ratio e/ (nus+antinus added)
Flavor composition at the source(Idealized – energy independent)
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However: flavor composition is energy dependent!
(from Hümmer, Maltoni, Winter, Yaguna, 2010; see also: Kashti, Waxman, 2005; Kachelriess, Tomas, 2006, 2007; Lipari et al, 2007)
Muon beam muon damped
Undefined(mixed source)
Pion beam
Pion beam muon damped
Behaviorfor small
fluxes undefined
Typicallyn beamfor low E(from p)
Energywindow
with largeflux for
classification
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Parameter space scan
All relevant regions recovered
GRBs: in our model =4 to reproduce pion spectra; pion beam muon damped (confirms Kashti, Waxman, 2005)
Some dependence on injection index
Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010
=2
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Flavor ratios at detector
Neutrino propagation in SM: At the detector: define observables which
take into account the unknown flux normalization take into account the detector properties
Example: Muon tracks to showersDo not need to differentiate between electromagnetic and hadronic showers!
Flavor ratios have recently been discussed for many particle physics applications
(for flavor mixing and decay: Beacom et al 2002+2003; Farzan and Smirnov, 2002; Kachelriess, Serpico, 2005; Bhattacharjee, Gupta, 2005; Serpico, 2006; Winter, 2006; Majumar and Ghosal, 2006; Rodejohann, 2006; Xing, 2006; Meloni, Ohlsson, 2006; Blum, Nir, Waxman, 2007; Majumar, 2007; Awasthi, Choubey, 2007; Hwang, Siyeon,2007; Lipari, Lusignoli, Meloni, 2007; Pakvasa, Rodejohann, Weiler, 2007; Quigg, 2008; Maltoni, Winter, 2008; Donini, Yasuda, 2008; Choubey, Niro, Rodejohann, 2008; Xing, Zhou, 2008; Choubey, Rodejohann, 2009; Bustamante, Gago, Pena-Garay, 2010, …)
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Effect of flavor mixing
Basic dependencerecovered afterflavor mixing
Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010
However: mixing parameter knowledge ~ 2015 required
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In short: Glashow resonance
Glashow resonance at 6.3 PeV can identify Can be used to identify p neutrino production in
optically thin (n) sources Depends on a number of conditions, such as
Hümmer, Maltoni, Winter, Yaguna,
Astropart. Phys. (to appear), 2010
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Summary
Flavor ratios should be interpreted as energy-dependent quantities
Flavor ratios may be interesting for astrophysics: e.g. information on magnetic field strength
The flavor composition of a point source can be predicted in our model if the astrophysical parameters are known
Our model is based on the simplest set of self-consistent assumptions without any empirical relationships
Parameter space scans, such as this one, are only possible with an efficient code for photohadronic interactions, weak decays, etc.: NeuCosmA For fits, stacking, etc. one describes real data, and therefore one
needs accurate neutrino flux predictions! References:
Hümmer, Rüger, Spanier, Winter, arXiv:1002.1310 (astro-ph.HE), ApJ 721 (2010) 630Hümmer, Maltoni, Winter, Yaguna, arXiv:1007.0006 (astro-ph.HE),Astropart. Phys. (to appear)
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Outlook: Magnetic field and flavor effects in GRB fluxes
Recipe:1. Reproduce WB flux
with -resonance including magnetic field effects explicitely
2. Switch on additional production modes, magnetic field effects, flavor effects (, flavor mixing)
Normalization increased by order of magnitude, shape totally different!
Implications???
Baerwald, Hümmer, Winter, to appear; see also: Murase, Nagataki, 2005; Kashti, Waxman, 2005; Lipari,
Lusignoli, Meloni, 2007
BACKUP
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Neutrino fluxes – flavor ratios
Hümmer, Maltoni, Winter, Yaguna, 2010
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Dependence on H
ümm
er, Maltoni, W
inter, Yaguna, 2010
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Neutrino propagation
Key assumption: Incoherent propagation of neutrinos
Flavor mixing: Example: For 13 =0, 12=/6, 23=/4:
NB: No CPV in flavor mixing only!But: In principle, sensitive to Re exp(-i ) ~ cos
Take into account Earth attenuation!
(see Pakvasa review, arXiv:0803.1701,
and references therein)
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Different event types
Muon tracks from Effective area dominated!(interactions do not have do be within detector)Relatively low threshold
Electromagnetic showers(cascades) from eEffective volume dominated!
Effective volume dominated Low energies (< few PeV) typically
hadronic shower ( track not separable) Higher Energies:
track separable Double-bang events Lollipop events
Glashow resonace for electron antineutrinos at 6.3 PeV (Learned, Pakvasa, 1995; Beacom et
al, hep-ph/0307025; many others)
e
e
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Flavor ratios (particle physics)
The idea: define observables which take into account the unknown flux normalization take into account the detector properties
Three observables with different technical issues: Muon tracks to showers
(neutrinos and antineutrinos added)Do not need to differentiate between electromagnetic and hadronic showers!
Electromagnetic to hadronic showers(neutrinos and antineutrinos added)Need to distinguish types of showers by muon content or identify double bang/lollipop events!
Glashow resonance to muon tracks(neutrinos and antineutrinos added in denominator only). Only at particular energy!