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Construction of a hadronic model for the production of neutrinos and the associated gamma-rays in galactic sources Prediction of neutrino signals in TeV-range (c.f. IceCube –south; Nemo -north) Analysis of correlated gamma-ray detection: luminosity and opacity

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slide2
Construction of a hadronic model for the production of neutrinos and the associated gamma-rays in galactic sources

Prediction of neutrino signals in TeV-range

(c.f. IceCube –south; Nemo -north)

Analysis of correlated gamma-ray detection: luminosity and opacity

(c.f. MAGIC: Major Atm. Gamma Imaging Cerenkov E>30GeV –North

HESS: High Energy Stereoscopic System E>100GeV –South

GLAST satelite E>100MeV)

Goals

slide3
Motivation:
  • High energy neutrinos can provide crucial data for the understanding of the origin of cosmic rays: where they come from, how are they produced, how are they accelerated ...
  • Neutrinos point straight to the source thus avoiding ambiguities, and are not absorbed along their long way
slide4
Cosmic Rays (CR)
  • 86 % protons, 11% alphas, 2% electrons and 1% heavy íons. NB: This 1% is particularly large as compared with the same quantity in the solar system (e.g. Li, Be, B, are several orders less present).
  • Most CR are relativistic (even ultra-relativistic, > 10(20) eV, of most enigmatic origin).
  • Most are non-solar but still galactic.
  • Interstellar secundaries are produced in primary CR versus interstellar íons collisions: their study can shed light on fields and particles of interstellar medium.
  • Neutrinos and photons secundaries produced near the source can explain their origin and the mechanism involved
slide5
Where to look for:
  • In our Galaxy, in (compact object + massive star) binary systems

Why:

  • compacts exhibit strong magnetic fields potential accelerators, massive stars present circumstellar matter fields lot of material for particle collisions.
  • Be /X binary systems present strong and variable radio and X ray emission, and are found within positional error boxes of gamma ray sources probably galactic probability of correlated neutrinos.
  • Disruption of magnetic fields can generate ejection phenomena : bipolar jets.
slide6

Microquasars: binary systems with jets.

Primary: massive B star, generates a matter field around.

Secondary: compact object, a mass accretor, generates a jet (neutron star or BH, determined by Doppler shift of absortion lines of the primary –analysis of changes of radial velocity vs. orbital position).

Miniatures of quasars.

slide8
LS I +61 303 is a galactic Be/X binary (den Heuvel & Rapapport 1987) distant 2.0 0.2 kpcs (Frail & Hjellming 1991) presents strong periodic radio emission (Gregory et al. 1979) and moderated periodic X (inverse-Compton) (Harrison et al. 2000).
  • Persistent radio bursts 2.5 - 4 days after periastron.
  • LS Ialready associated with gamma ray sources 2CG 135 +01 (Kniffen et al. 1997), and 3EG J0241 +61 03 (Hartman et al. 1999). Recently stated byEGRET main peak coincident with periastron (Massi 2004)
slide9
Explanation: Microquasars, bizarre binary star systems generating high-energy radiation and blasting out jets of particles at nearly the speed of light, live in our Milky Way galaxy. The energetic microquasar systems seem to consist of a very compact object, either a neutron star or a black hole, formed in a supernova explosion but still co-orbiting with an otherwise normal star. Using a very long array of radio telescopes, astronomers are reporting that at least one microquasar, LSI +61 303, can be traced back to its probable birthplace -- within a cluster of young stars in the constellation Cassiopeia. About 7,500 light-years from Earth, the star cluster and surrounding nebulosity, IC 1805, are shown in the deep sky image above. The cluster stars are identified by yellow boxes and circles. A yellow arrow indicates the common apparent motion of the cluster stars, the green arrow shows the deduced sky motion of the microquasar system, and the red arrow depicts the microquasar's motion relative to the star cluster itself. Seen nearly 130 light-years from the cluster it once called home, a powerful kick from the original supernova explosion likely set this microquasar in motion. Credit: I. F. Mirabel, I. Rodrigues, Q. Z. Liu, NRAO / AUI / NSF

2004 September 24

slide10
Primary: B0 V [white-blue,10-18 , main seq. (dwarf)] dense fast matter wind - equatorial disc (Be) (Hutchings & Crampton 1981, by UV spectroscop. Paredes & Figueras 1986, photometr. anal.) orbit 26.5 days (radio, Gregory 2002), high eccentricity 0.72 (IR spectrosc., Martí & Paredes 1995).
  • Secundary: probably neutron star with a bipolar jet of 200 AU each (dist. Earth-Sun).
  • Presumed presence of protons in the jet. c.f. microquasar SS 433 (first discovered, Margon 1979) íons detected in jet(Migliari al. 2002, X ray analysis).
model of microquasar lsi
Model of microquasar LSI
  • Be starcircumstellar disc distribution density (Marti & Paredes 1995, Gregory & Neish 2002)
  • wind velocity
  • Everything given by orbital position (keplerian) major semiaxes a, higheccentricity e= 0.72 (psi=0.23 at periastron, Casares 2005)
slide13
Mass accretion rate depends on relative velocity of neutron star with respect to the (radial) wind velocity.
  • Accretion rate and jet kinetic power are proportional (Falcke & Biermann 1995)
  • For jet cold protons qj=0.1 (Lorentz factor = 1.25, Massi et al. 2001). qj =0.01 – 0.001 for relativistic jet protons.
  • Conic jet, normal to orbital plane, with injection point and radius at base R0 = z0 /10
slide14
High energy neutrinos: arise from collisions of relativistic (jet) protons and cold (wind) protons after pion decay
  • On average, 1/3 of the energy goes into each flavor
  • Both products are easily correlated:

2 and 2 mean energy E /4 each, for each mean energy E /2

E = E / 2

microscopics
Microscopics
  • Proton flux along the jet axis (ph/erg cm2 s): power law

=2.2 (reproduces EGRET obs.); in lab/observer frame

  • angle between proton and jet axis -approx. emerging photon or observing position: (Casares et al. 2005)
  • bulk vel. (c units).
  • Ko normalization cons., related to particle density at base (Romero et al. 2003)
magnetic field penetration and acceleration
Magnetic field, Penetration and Acceleration
  • Provided p gyro-radius smaller than cone radius, it can penetrate inside. Magnetic field must be

namely Bjet>2.8 10^-6 G

  • shock formation in boundary layers prevents penetration thus introduce a penetration factor fp = 0.1 (reproduces GeV gamma ray flux observed by EGRET)

Admitting

  • Difussive particle acceleration by quasi-parallel shocks
  • Adiabatic field and matter evolution along the jet
  • Equipartition of energy between B and jets cold protons
  • Larmor radius= jet radius then proton Emax
slide18
Pion Multiplicity
  • For Ep<10TeV (Mannheim & Schilckeiser 1994)
  • For Ep higher we extrapolate with a 1/5 power such that psi=14 at Ep=100 TeV (Orth 1976) and for Ep>100TeV with 1/6 power implying psi=26 for Ep=50PeV
  • (Ginzburg & Syravatskii)
  • K=0.5 inelasticity coef. (on average, pions leave the fireball with half the max. energy)
  • E =1/2 E (aver. kinematics)
slide19
Maximal neutrino energy(it results from orbital variation of maximal proton energy and pion multiplicity)
neutrino signal noise
Neutrino Signal (& noise)
  • Convolution of source intensity and event probability
  • Convolution of atmospheric flux
flux of neutrinos out of gamma flux
Flux of neutrinos out of gamma flux

Conservation of energy relates luminosities of neutrino & gamma

Average production kinematics in decay

In the reaction channel pp: D =1

slide22
Spectral intensity (ph/s erg):

V : interaction region between jet & wind

  • Density of wind particles penetrating the jet
slide23
Gamma-ray emissivity from decays

(e.g. Aharonian & Atoyan 1996):

  • spectral moment, related to the fraction of kinetic energy transferred to the pion (Gaisser 1990)
  • =1.4 takes into account the contribution of different nuclei in wind and jet
tev neutrino events detectable by icecube
TeV-neutrino events detectable by ICECUBE

Production of mu-neutrinos at the source

(c.f. upper limit of AMANDA II 2005)

neutrino mixing
Neutrino mixing

flavoroscillations (e.g. SNO 2002, solar).

Relative neutrino production at source (pp):

Becomes 1 : 1 : 1 for astrophysical distances

such that (Athar et al. 2005)

50% reductionmu-nu flux

(Costantini & Vissani 2005)

total luminosity lsi
Total luminosity LSI
  • From 30 GeV up to:

(vide MAGIC 2005)

  • Excess (x4) over experimental limit for total intensity for E >350 GeV (Fegan et al. 2005):
local source opacity
Local (source) Opacity
  • Optical depth for a gamma ray among ambient photons

distance to the neutron star:

Threshold for pair creation:

Cross section of the reaction:

me, r0 electron mass and radius

slide28
Main contributions given by photon densities

nph1 (Be star), and nph2 (disk)

The black body bright function

= 22500 K, = 17500 K (Martí & Paredes 1995).

conclusions
Conclusions
  • Model for production of galactic neutrinos and correlated gamma-rays: hadronic origin.
  • case study: microquasar LSI (recent parameters)
  • Predictions compatible with observed periodicity in gamma frequencies (EGRET 2004). Pronounced peak at periastron, secondary maximum near apastron in contrast with radio/X frequencies. (lepton models have difficulties with this).
  • Predictions of luminosity (source) and detectability:

neutrino signal to noise relationship, and gamma

opacity: correlated ICECUBE and MAGIC briefly…