Neutrino flavor ratios from cosmic accelerators on the Hillas plot NOW 2010 September 4-11, 2010 C onca Specchiulla (Otranto, Lecce, Italy) Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAA A A A

2 Contents  Introduction  Meson photoproduction  Our model  Flavor composition at source  Hillas plot and parameter space scan  Flavor ratios/flavor composition at detector  Summary

3 From Fermi shock acceleration to production Example: Active galaxy (Halzen, Venice 2009)

4  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 physics Mücke, Rachen, Engel, Protheroe, Stanev, 2000 Limitations: 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

5 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 of weak decays: muon helicity!

6 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! ?

7 Optically thin to neutrons Model summary Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010 Dashed arrow: Steady state Balances injection with energy losses and escape Q(E) [GeV -1 cm -3 s -1 ] per time frame N(E) [GeV -1 cm -3 ] steady spectrum InjectionEnergy lossesEscape Dashed arrows: include cooling and escape

8 A typical example Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010  =2, B=10 3 G, R= km Maximum energy: e, p Cooling: charged , , K

9 A typical example (2) Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010  =2, B=10 3 G, R= km  cooling break  cooling break Pile-up effect Pile-up effect  Flavor ratio! Slope:  /2 Synchrotron cooling Spectral split

10 The Hillas plot  Hillas (necessary) condition for highest energetic cosmic rays (  : acc. eff.)  Protons, 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

11  Astrophysical neutrino sources produce certain 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-dissociation of heavy nuclei or neutron decays  At the source: Use ratio e /  (nus+antinus added) Flavor composition at the source (Idealized – energy independent)

12 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 Behavior for small fluxes undefined Typically n beam for low E (from p  ) Energy window with large flux for classification

13 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

14 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 ; 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, …)

15 Effect of flavor mixing  Basic dependence recovered after flavor mixing Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. (to appear), 2010  However: mixing parameter knowledge ~ 2015 required

16 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

17 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: (astro-ph.HE), ApJ 721 (2010) 630 Hümmer, Maltoni, Winter, Yaguna, arXiv: (astro-ph.HE), Astropart. Phys. (to appear)

18 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

20 Neutrino fluxes – flavor ratios Hümmer, Maltoni, Winter, Yaguna, 2010

21 Dependence on  Hümmer, Maltoni, Winter, Yaguna, 2010

22 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: , and references therein)

23 Different event types  Muon tracks from  Effective area dominated! (interactions do not have do be within detector) Relatively low threshold  Electromagnetic showers (cascades) from e Effective 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/ ; many others)   e e   

24 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!