Magnetic field and flavor effects on the neutrino fluxes from cosmic accelerators
Download
1 / 32

Magnetic field and flavor effects on the neutrino fluxes from cosmic accelerators - PowerPoint PPT Presentation


  • 85 Views
  • Uploaded on

Magnetic field and flavor effects on the neutrino fluxes from cosmic accelerators. WIN 2011 January 31-February 5, 2011 Cape Town , South Africa Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Introduction

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Magnetic field and flavor effects on the neutrino fluxes from cosmic accelerators' - rod


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Magnetic field and flavor effects on the neutrino fluxes from cosmic accelerators

Magnetic field and flavor effects on the neutrino fluxes from cosmic accelerators

WIN 2011

January 31-February 5, 2011Cape Town, South Africa

Walter Winter

Universität Würzburg

TexPoint fonts used in EMF: AAAAAAAA


Contents
Contents from cosmic accelerators

  • Introduction

  • Simulation of sources, a self-consistent approach

  • Neutrino propagation and detection;flavor ratios

  • On gamma-ray burst (GRB) neutrino fluxes

  • Summary


Neutrino production in astrophysical sources
Neutrino production in astrophysical sources from cosmic accelerators

max. center-of-mass energy ~ 103 TeV(for 1021 eV protons)

Example: Active galaxy(Halzen, Venice 2009)


Neutrino detection icecube
Neutrino detection: IceCube from cosmic accelerators

  • Example: IceCube at South PoleDetector material: ~ 1 km3antarctic ice

  • Completed 2010/11 (86 strings)

  • Recent data releases, based on parts of the detector:

    • Point sources IC-40arXiv:1012.2137

    • GRB stacking analysis IC-40arXiv:1101.1448

    • Cascade detection IC-22arXiv:1101.1692

http://icecube.wisc.edu/


Example grb stacking
Example: GRB stacking from cosmic accelerators

(Source: IceCube)

  • Idea: Use multi-messenger approach

  • Predict neutrino flux fromobserved photon fluxesevent by event

  • Good signal over background ratio (atmospheric background), moderate statistics

(Source: NASA)

Coincidence!

Neutrino observations(e.g. IceCube, …)

GRB gamma-ray observations(e.g. Fermi GBM, Swift, etc)

(Example: IceCube, arXiv:1101.1448)


Ic 40 data meet generic bounds
IC-40 data meet generic bounds from cosmic accelerators

(arXiv:1101.1448)

  • Generic flux based on the following assumptions:- GRBs are the sources of (highest energetic) cosmic rays- Fraction of energy the protons loose in pion production ~ 20%(Waxman, Bahcall, 1999; Waxman, 2003)

What do such bounds actually mean more generically? Limit

IC-40 stacking limit

Fraction of p energy lost into pion production(related to optical thicknessof pg/ng interactions)

Baryonic loading(ratio between protons andelectrons/positrons in the jet)

X


When do we expect a n signal some personal comments
When do we expect a from cosmic acceleratorsn signal?[some personal comments]

  • Unclear if specific sources lead to neutrino production; spectral energy distribution can be often described by leptonic processes as well (e.g. inverse Compton scattering, …)

  • However: whereever cosmic rays are produced, neutrinos should be produced as well (pg, pp!)

  • There are a number of additional candidates, e.g.

    • „Hidden“ sources (e.g. „slow jet supernovae“ without gamma-ray counterpart)(Razzaque, Meszaros, Waxman, 2004; Ando, Beacom, 2005; Razzaque, Meszaros, 2005; Razzaque, Smirnov, 2009)

    • Large fraction of Fermi-LAT unidentified sources?

  • From the neutrino point of view: „Fishing in the dark blue sea“? Looking at the wrong places?

  • Need for tailor-made neutrino-specific approaches?


Simulation of sources

Simulation of sources from cosmic accelerators


Meson photoproduction
Meson photoproduction from cosmic accelerators

  • Often used: D(1232)-resonance approximation

  • Limitations:

    • No p- production; cannot predict p+/ p- ratio (affects neutrino/antineutrino)

    • 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 physicsMücke, Rachen, Engel, Protheroe, Stanev, 2000Limitations: Often slow, difficult to handle; helicity dep. muon decays!

    • Parameterizations based on SOPHIA

      • Kelner, Aharonian, 2008Fast, but no intermediate muons, pions (cooling cannot be included)

      • Hümmer, Rüger, Spanier, Winter, 2010Fast (~3000 x SOPHIA), including secondaries and accurate p+/ p- ratios; also individual contributions of different processes (allows for comparison with D-resonance!)

      • Engine of the NeuCosmA („Neutrinos from Cosmic Accelerators“) software

from:Hümmer, Rüger, Spanier, Winter, ApJ 721 (2010) 630

T=10 eV


Neucosma key ingredients neu trinos from cosm ic a ccelerators
NeuCosmA key ingredients from cosmic accelerators(„Neutrinos from Cosmic Accelerators“)

  • 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!)

Kinematics ofweak decays: muon helicity!

from: Hümmer, Rüger, Spanier, Winter, ApJ 721 (2010) 630


A self consistent approach
A self-consistent approach from cosmic accelerators

  • Target photon field typically:

    • Put in by hand (e.g. obs. spectrum: GRBs)

    • Thermal target photon field

    • From synchrotron radiation of co-accelerated electrons/positrons (AGN-like)

  • Requires few model parameters, mainly

  • Purpose: describe wide parameter ranges with a simple model; minimal set of assumptions for n!?

?


Model summary
Model summary from cosmic accelerators

Dashed arrows: include cooling and escape

Dashed arrow: Steady stateBalances injection with energy losses and escapeQ(E) [GeV-1 cm-3 s-1] per time frameN(E) [GeV-1 cm-3] steady spectrum

Opticallythinto neutrons

Injection

Energy losses

Escape

Hümmer, Maltoni, Winter, Yaguna, Astropart. Phys. 34 (2010) 205


An example 1
An example (1) from cosmic accelerators

a=2, B=103 G, R=109.6 km

  • Meson production described by(summed over a number of interaction types)

    • Only product normalization enters in pion spectra as long as synchrotron or adiabatic cooling dominate

  • Maximal energy of primaries (e, p) by balancing energy loss and acceleration rate

Maximum energy: e, p

Hümmer, Maltoni, Winter, Yaguna, 2010


An example 2
An example (2) from cosmic accelerators

a=2, B=103 G, R=109.6 km

  • Secondary spectra (m, p, K) become loss-steepend above a critical energy

    • Ec depends on particle physics only (m, t0), and B

    • Leads to characteristic flavor composition

    • Any additional cooling processes mainly affecting the primaries will not affect the flavor composition

    • Flavor ratios most robust predicition for sources?

Cooling: charged m, p, K

Ec

Ec

Ec

Hümmer, Maltoni, Winter, Yaguna, 2010


An example 3
An example (3) from cosmic accelerators

a=2, B=103 G, R=109.6 km

m cooling break

Synchrotroncooling

Spectralsplit

p cooling break

Pile-up effect Flavor ratio!

Pile-upeffect

Slope:a/2

Hümmer, Maltoni, Winter, Yaguna, 2010


The hillas plot
The Hillas plot from cosmic accelerators

  • Hillas (necessary) condition for highest energetic cosmic rays (h: acc. eff.)

  • Protons, 1020 eV, h=1:

  • We interpret R and B as parameters in bulk frame

    • High bulk Lorentz factors G relax this condition!

Hillas 1984; version adopted from M. Boratav


Magnetic field and flavor effects on the neutrino fluxes from cosmic accelerators

Flavor composition at the source from cosmic accelerators(Idealized – energy independent)

  • Astrophysical neutrino sources producecertain 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)Cooled muons pile up at lower energies (also: heavy flavor decays)

  • Neutron beam source (1:0:0)Neutron decays from pg(also possible: photo-dissociationof heavy nuclei)

  • At the source: Use ratio ne/nm (nus+antinus added)


However flavor composition is energy dependent
However: flavor composition is energy dependent! from cosmic accelerators

Pion beam

Muon beam muon damped

Energywindowwith largeflux for classification

Typicallyn beamfor low E(from pg)

Pion beam muon damped

Undefined(mixed source)

Behaviorfor smallfluxes undefined

(from Hümmer, Maltoni, Winter, Yaguna, 2010; see also: Kashti, Waxman, 2005; Kachelriess, Tomas, 2006, 2007; Lipari et al, 2007)


Parameter space scan
Parameter space scan from cosmic accelerators

  • All relevant regions recovered

  • GRBs: in our model a=4 to reproduce pion spectra; pion beam  muon damped (confirmsKashti, Waxman, 2005)

  • Some dependence on injection index

a=2

Hümmer, Maltoni, Winter, Yaguna, 2010


Neutrino propagation and detection

Neutrino propagation and detection from cosmic accelerators


Neutrino propagation
Neutrino propagation from cosmic accelerators

  • Key assumption: Incoherent propagation of neutrinos

  • Flavor mixing:

  • 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!

(see Pakvasa review, arXiv:0803.1701, and references therein)


Which sources can specific data constrain best
Which sources can specific data constrain best? from cosmic accelerators

  • Constrain individual fluxes after flavor mixing with existing data

Point sources IC-40arXiv:1012.2137

Energy flux density

PRELIMINARY

(work in preparation)


Measuring flavor
Measuring flavor? from cosmic accelerators

  • In principle, flavor information can be obtained from different event topologies:

    • Muon tracks - nm

    • Cascades (showers) – CC: ne, nt, NC: all flavors

    • Glashow resonance: ne

    • Double bang/lollipop: nt

      (Learned, Pakvasa, 1995; Beacom et al, 2003)

  • In practice, the first (?) IceCube „flavor“ analysis appeared recently – IC-22 cascades (arXiv:1101.1692)Flavor contributions to cascades for E-2 extragalatic test flux (after cuts):

    • Electron neutrinos 40%

    • Tau neutrinos 45%

    • Muon neutrinos 15%

  • Electron and tau neutrinos detected with comparable efficiencies

  • Neutral current showers are a moderate background

t

nt


Flavor ratios at detector
Flavor ratios at detector from cosmic accelerators

  • 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; Esmaili, Farzan, 2009; Bustamante, Gago, Pena-Garay, 2010; Mehta, Winter, 2011…)


Parameter uncertainties
Parameter uncertainties from cosmic accelerators

  • Basic dependencerecovered afterflavor mixing

  • However: mixing parameter knowledge ~ 2015 (Daya Bay, T2K, etc) required

Hümmer, Maltoni, Winter, Yaguna, 2010


New physics in r
New physics in R? from cosmic accelerators

Energy dependenceflavor comp. source

Energy dep.new physics

(Example: [invisible] neutrino decay)

1

Stable state

1

Unstable state

Mehta, Winter, arXiv:1101.2673


Which sources are most useful
Which sources are most useful? from cosmic accelerators

  • Most useful:Sources for which different flavor compositions are present; requires substantial B

  • Some dependence on new physics effect

aL=108 GeV

No of decayscenarios which canbe identified

Mehta, Winter, arXiv:1101.2673


On grb neutrino fluxes

On GRB neutrino fluxes from cosmic accelerators


Waxman bahcall reproduced
Waxman-Bahcall, reproduced from cosmic accelerators

  • Difference to above: target photon field ~ observed photon field used

  • Reproduced original WB flux with similar assumptions

  • Additional charged pion production channels included,also p-!

broken power law(Band function)

p decays only

~ factor 6

Baerwald, Hümmer, Winter, arXiv:1009.4010


Fluxes before flavor mixing
Fluxes before flavor mixing from cosmic accelerators

ne

nm

Baerwald, Hümmer, Winter, arXiv:1009.4010


After flavor mixing
After flavor mixing from cosmic accelerators

Consequences:

  • Different flux shape

    • Can double peak structure be used?

    • How reliable is stacking analysis from IC-40?

  • Different normalization

    • Expect actually more neutrinos than in original estimates

    • Baryonic loading x fpstronger constrained?

    • GRBs not the sourcesof highest energetic CR?

(full scale)

(full scale)

Baerwald, Hümmer, Winter, arXiv:1009.4010; see also: Murase, Nagataki, 2005; Kashti, Waxman, 2005; Lipari, Lusignoli, Meloni, 2007


Summary
Summary from cosmic accelerators

  • Particle production, flavor, and magnetic field effects change the shape of astrophysical neutrino fluxes

    • Description of the „known“ (particle physics) components should be as accurate as possible for data analysis

  • Flavor ratios, though difficult to measure, are interesting because

    • they may be the only way to directly measure B (astrophysics)

    • they are useful for new physics searches (particle physics)

    • they are relatively robust with respect to the cooling and escape processes of the primaries (e, p, g)

  • However: flavor ratios should be interpreted as energy-dependent quantities

  • The flux shape and flavor ratio of a point source can be predicted in a self-consistent way if the astrophysical parameters can be estimated, such as from a multi-messenger observation (R: from time variability, B: from energy equipartition, a: from spectral shape)