Gamma-rays, neutrinos and cosmic rays Gamma-rays, neutrinos and cosmic rays from microquasarsfrom microquasars

Gustavo E. RomeroGustavo E. Romero(IAR – CONICET & La Plata University, Argentina)(IAR – CONICET & La Plata University, Argentina)

Email: romero@fcaglp.unlp.edu.arEmail: romero@fcaglp.unlp.edu.ar

Grupo de Astrofísica Relativista y Radioastronomía (GARRA)

Trondheim, June 2009

Microquasars

Microquasars (MQs) are accreting binaries formed by a compact object and a donor star. The compact object can be a neutron star (e.g. as in Sco X-1) or a black hole (e.g. Cygnus X-1). The donor star can be of an early type or a low-mass star.

MQs present non-thermal jets. This means that there are relativistic particles in the jets.

In the environment of a MQ the presence of relativistic particles can result in the production of detectable gamma-rays and neutrinos (e.g. Levinson & Blandford 1996, Romero et al. 2003).

› Compact object

› Donor star

› Accretion disk

› Hot corona

› Relativistic jets

Main components of a microquasar

Low-hardLow-hard

•

•

•

keV

keV

keV

keV

High-soft

›

›

›

Spectral states

MQs display different X-ray spectral states:- Low/hard state (a.k.a. power-law state). Compact radio jet.- High/soft state (a.k.a. thermal-dominant state). No radio emission.- Intermediate and very high states transitions. Transient radio emission.

(Fender 2001)

MQs states and types of jets

SS433: a precessing microquasar with heavy jetsSS433: a precessing microquasar with heavy jets

Jets with high kinetic power: Jets with high kinetic power: LLkk=10=103939erg/serg/s

Fe lines from detected from jets Fe lines from detected from jets (Migliari et al. 2002)(Migliari et al. 2002)

Jets and extended disk wind in Jets and extended disk wind in precession (precession (PPprecprec=162 d)=162 d)

Potential neutrino source (Eichler Potential neutrino source (Eichler 1980, Reynoso et al. 2008)1980, Reynoso et al. 2008)

VLBA

Evidence for relativistic hadrons in MQ jetsEvidence for relativistic hadrons in MQ jets

Migliari et al. 2002; Kotani 1994, 1996

Migliari et al. 2002

SS433

a cartoon…a cartoon…

Relativistic particles in the jetsRelativistic particles in the jets

Local magnetic fieldLocal magnetic field::

Shock acceleration of electrons and protonsShock acceleration of electrons and protons

Rate:Rate:

Power in relativistic particles:Power in relativistic particles:

One-zone approximation (e.g. Khangulyan et al. 2007)One-zone approximation (e.g. Khangulyan et al. 2007)

Acceleration zoneAcceleration zone

zz00

JetJet

BHBH

andand

Injection function:Injection function: ((GeVGeV-1-1 cm cm-3-3 s s-1-1 sr sr-1-1))

LLrelrel is a fraction is a fraction qqrel rel of kinetic powerof kinetic power

Content of relativistic particles Initial magnetic field

Simple model

Compact acceleration/emission region located where the field falls below equipartition

Mildly relativistic outflow, =1.5

Conical jet, perpendicular to binary orbit

Viewing angle =30º, moderate

Falcke & Biermann (1995)

Körding et al. (2006)

Particle distributions “one-zone” approximation

diffusive shock acceleration

~ 2.2

(Khangulyan et al. 2007)

Interaction of

relativistic p and e- with

magnetic field

radiation fields

in the jet

, , p e B p e

e e

( ) op p a b 2o

p p e e

• Synchrotron radiation

• Inverse Compton (IC)

• Photohadronic interactions (p)

v e ee

e B e

( ) op n a b

• Proton-proton inelastic collisions p + p p + p + a 0+ b(+ +-)

The proton microquasr jet modelThe proton microquasr jet model (Romero & Vila, A&A (Romero & Vila, A&A 485, 623 (2008), also Romero & Vila, A&A, 485, 623 (2008), also Romero & Vila, A&A, 494, L33 (2009) ) )

Particle lossesParticle losses

Proton escapeProton escape

Protons with energies beyond 1PeV can Protons with energies beyond 1PeV can be produced.be produced.

Main losses for protons are synchrotron Main losses for protons are synchrotron but locally produced energetic neutrons but locally produced energetic neutrons can escape:can escape:

Then, the neutrons decay outside the Then, the neutrons decay outside the region of high magnetic field injecting region of high magnetic field injecting protons, electrons and anti-neutrinosprotons, electrons and anti-neutrinos

Case of SS 433Case of SS 433

Reynoso, Romero & Christiansen, MNRAS 387, 1747, 2008

Romero & Vila, A&A, 494, L33 (2009)

Magnetic field effects on neutrino productionMagnetic field effects on neutrino production

Reynoso & Romero A&A, 493, 1 (2009)

Charged pions and muon distributionsCharged pions and muon distributions

Magnetic field effects on neutrino productionMagnetic field effects on neutrino production

Reynoso & Romero A&A, 493, 1 (2009)

SS 433: Differential Neutrino flux at EarthSS 433: Differential Neutrino flux at Earth

SS 433: Integrated neutrino fluxSS 433: Integrated neutrino flux

Here, qrel= 10-3

Gamma-ray absorption in MQsGamma-ray absorption in MQs

γγ-rays can be absorbed by:-rays can be absorbed by:

Optical depthOptical depth

Differential optical depth

Reynoso et al. APh, 28, 565 (2008)

Gamma-ray absorption in SS433:

Absorption due to Absorption due to γγγγ interactions interactions

Target photons from the starTarget photons from the star::

Differential optical depthDifferential optical depth (Gould & Schreder 1967)(Gould & Schreder 1967)

with with TT✹✹=8500 K for SS433=8500 K for SS433 Target photons from the extended diskTarget photons from the extended disk

UV emission: Black body with UV emission: Black body with TT= 21000 K, (10= 21000 K, (103 3 Å < Å < λλ <10 <104 4 Å)Å)

RRUV UV = 33 R= 33 R ✹ ✹ (Gies et al. 2002)(Gies et al. 2002)

IR emission: , IR emission: , (2µm < (2µm < λλ <12 <12 µm)µm)

RRIRIR= 50 = 50 RR ✹ ✹ (Fuchs et al. 2005) (Fuchs et al. 2005)

γγγγ absorptionabsorption Starlight contribution

Gamma-ray absorption in SS433:

γγγγ absorptionabsorptionContribution due to IR emission Contribution due to IR emission Contribution due to UV emissionContribution due to UV emission

Gamma-ray absorption in SS433:

Absorption due to Absorption due to γγN N interactionsinteractions

Optical depthOptical depth

Cross sectionCross section

Density of the star:

Density of the extended disk:

Gamma-ray absorptionabsorption in SS433:

γN optical depthGamma-ray absorption in SS433:

Total optical depthTotal optical depth

For For γγ-rays originated at jet base-rays originated at jet base

Gamma-ray absorption in SS433:Gamma-ray absorption in SS433:

Effects on a gamma signalEffects on a gamma signal Gamma-ray absorption in SS433: Gamma-ray absorption in SS433:

Integrated gamma-ray fluxes for SS 433Integrated gamma-ray fluxes for SS 433

Positrons are copiously produced by internal Positrons are copiously produced by internal absorption and charged muon decaysabsorption and charged muon decays

INTEGRAL results (Weidenspointener et al., Nature 451, 159 (2008)

Annihilation line distribution

LMXRBs distribution

Models with a=100 produces around 1042 positrons/s

Lepto/hadronic models for LMXRB Lepto/hadronic models for LMXRB (Vila & Romero, in preparation)(Vila & Romero, in preparation)

GX 339-4

PAMELA positron fractionPAMELA positron fraction

Final commentsFinal comments The consistency of the models presented can be tested with present The consistency of the models presented can be tested with present

and future neutrino and gamma-ray observations.and future neutrino and gamma-ray observations.

MQs can be sources of comic rays up to energies of the order of the MQs can be sources of comic rays up to energies of the order of the knee.knee.

MQs can also be an important source of positrons in the Galaxy MQs can also be an important source of positrons in the Galaxy A more realistic treatment is necessary to refine predictions: e.g. go A more realistic treatment is necessary to refine predictions: e.g. go

beyond the one-zone approximation.beyond the one-zone approximation.

Thank you!Thank you!

Parameters of the model for SS433Parameters of the model for SS433