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Physik am Samstag by ewghwehws


									Neutrino flavor ratios from cosmic
accelerators on the Hillas plot

    NOW 2010
    September 4-11, 2010
    Conca Specchiulla (Otranto, Lecce,

    Walter Winter
    Universität Würzburg
   Introduction
   Meson photoproduction
   Our model
   Flavor composition at source
   Hillas plot and parameter space scan
   Flavor ratios/flavor composition at detector
   Summary

                From Fermi shock acceleration to
                n production

Example: Active galaxy
 (Halzen, Venice 2009)
                         Meson photoproduction
 Often used: D(1232)-
  resonance approximation
 Limitations:
   -   No p- production; cannot predict p+/ p- ratio
   -   High energy processes affect spectral shape
   -   Low energy processes (t-channel) enhance charged pion production
      Charged pion production underestimated compared to p0 production by
       factor of > 2.4 (independent of input spectra!)
 Solutions:
    SOPHIA: most accurate description of physics
     Mücke, Rachen, Engel, Protheroe, Stanev, 2000
     Limitations: Often slow, difficult to handle; helicity dep. muon decays!
    Parameterizations based on SOPHIA
                                                                       Hümmer, Rüger,
         Kelner, Aharonian, 2008                                       Spanier, Winter,
          Fast, but no intermediate muons, pions (cooling cannot be included)
                                                                     ApJ 721 (2010) 630
         Hümmer, Rüger, Spanier, Winter, 2010
          Fast (~3000 x SOPHIA), including secondaries and accurate p+/ p- ratios;
                                                 T=10 eV
          also individual contributions of different processes (allows for comparison
          with D-resonance!)
         Engine of the NeuCosmA („Neutrinos from Cosmic Accelerators“) software
                       NeuCosmA key ingredients
 What it can do so far:
    Photohadronics based on SOPHIA
     (Hümmer, Rüger, Spanier, Winter, 2010)
    Weak decays incl. helicity                         Kinematics of
     dependence of muons
     (Lipari, Lusignoli, Meloni, 2007)                  weak decays:
    Cooling and escape                                 muon helicity!

 Potential applications:
    Parameter space studies
    Flavor ratio predictions
    Time-dependent AGN simulations
     etc. (photohadronics)
    Monte Carlo sampling of diffuse
    Stacking analysis with measured
     target photon fields
    Fits (need accurate description!)        from: Hümmer, Rüger, Spanier,
    …                                            Winter, ApJ 721 (2010) 630

                  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
 Requires few model parameters

  (synchtrotron cooling dominated  only overall normalization factor)
 Purpose: describe wide parameter ranges with a
  simple model; no empirical relationships needed!                       6
                   Model summary
Dashed arrows: include cooling and escape

                         Dashed arrow: Steady state
                         Balances injection with energy losses and escape

                             Injection             Energy losses   Escape
                         to neutrons

                         Q(E) [GeV-1 cm-3 s-1] per time frame
                         N(E) [GeV-1 cm-3] steady spectrum

                               Hümmer, Maltoni,
                                Winter, Yaguna,
                                Astropart. Phys.
                               (to appear), 2010

             A typical example
                                                    a=2, B=103 G, R=109.6 km

Maximum energy: e, p                           Cooling: charged m, p, K

 Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010
             A typical example (2)
                                                       a=2, B=103 G, R=109.6 km

m cooling                  Synchrotron
  break                      cooling                                     Spectral
                        p cooling        Pile-up effect                   split
Pile-up                   break           Flavor ratio!


   Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010
                    The Hillas plot

 Hillas (necessary)
  condition for highest
  energetic cosmic rays
  (h: acc. eff.)
 Protons, 1020 eV, h=1:

 We interpret R and B as
  parameters in source
   High source Lorentz factors G
    relax this condition!           Hillas 1984; version adopted from M. Boratav
               Flavor composition at the source
               (Idealized – energy independent)
 Astrophysical neutrino sources produce
  certain flavor ratios of neutrinos (ne:nm:nt):
 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
  of heavy nuclei or neutron decays
 At the source: Use ratio ne/nm (nus+antinus added)
                              However: flavor composition is energy

 Muon beam
                                                                                             Pion beam
 muon damped

    window                                                                                       Typically
   with large                                                                                     n beam
    flux for                                                                                     for low E
 classification                                                                                  (from pg)

  Undefined                                                                                Pion beam
(mixed source)                                                                            muon damped

                                                                                              for small
                              (from Hümmer, Maltoni, Winter, Yaguna, 2010;
           see also: Kashti, Waxman, 2005; Kachelriess, Tomas, 2006, 2007; Lipari et al, 2007)               12
                     Parameter space scan
 All relevant regions                                                          a=2
 GRBs: in our model
  a=4 to reproduce
  pion spectra; pion
  beam  muon
  (confirms Kashti, Waxman,

 Some dependence
  on injection index
          Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010
                           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 showers
  Do 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, …)                                                                         14
                        Effect of flavor mixing
                                        Basic dependence
                                         recovered after
                                         flavor mixing

 However: mixing
  knowledge ~ 2015
  Hümmer, Maltoni, Winter, Yaguna,
  Astropart. Phys. (to appear), 2010                        15
              In short: Glashow resonance
 Glashow resonance at 6.3 PeV can identify
 Can be used to identify pg neutrino production
  in optically thin (n) sources
 Depends on a number of conditions, such as G

                                        Hümmer, Maltoni,
                                          Winter, Yaguna,
                                       Astropart. Phys. (to
                                            appear), 2010

 Flavor ratios should be interpreted as energy-dependent
 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) 630
    Hümmer, Maltoni, Winter, Yaguna, arXiv:1007.0006 (astro-ph.HE),
    Astropart. Phys. (to appear)

                Outlook: Magnetic field and flavor
                effects in GRB fluxes
1. Reproduce WB flux
   with D-resonance
   including magnetic
   field effects explicitely
2. Switch on additional n
   production modes,
   magnetic field effects,
   flavor effects (m,
   flavor mixing)
 Normalization
   increased by order of
   magnitude, shape                 Baerwald, Hümmer, Winter, to
                                 appear; see also: Murase, Nagataki,
   totally different!            2005; Kashti, Waxman, 2005; Lipari,
 Implications???                      Lusignoli, Meloni, 2007
Neutrino fluxes – flavor ratios

 Hümmer, Maltoni, Winter, Yaguna, 2010   20

                  Hümmer, Maltoni, Winter, Yaguna, 2010
Dependence on a
                Neutrino propagation
 Key assumption: Incoherent propagation of
  neutrinos                          (see Pakvasa review,
 Flavor mixing:                    and references therein)

 Example: For q13 =0, q12=p/6, q23=p/4:

 NB: No CPV in flavor mixing only!
  But: In principle, sensitive to Re exp(-i d) ~ cosd
 Take into account Earth attenuation!
                  Different event types
 Muon tracks from nm
  Effective area dominated!
  (interactions do not have do be
  within detector)
  Relatively low threshold
 Electromagnetic showers                                              t
  (cascades) from ne                                                        nt
  Effective volume dominated!
 nt: Effective volume dominated                                   e
    Low energies (< few PeV) typically                                ne
     hadronic shower (nt track not
    Higher Energies:
      nt track separable                                               nm
       Double-bang events
       Lollipop events
 Glashow resonace for electron           (Learned, Pakvasa, 1995; Beacom et
                                            al, hep-ph/0307025; many others)
  antineutrinos at 6.3 PeV
                    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!

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