1. Accrétion et éjection dans les systèmes binaires d’haute énergie
Séminaire multi-échelles SAp
Gif-sur-Yvette, 2006 Avril 05
Accrétion et éjection dans les systèmes binaires d’haute énergie
Marc Ribó CEA Saclay

2. OUTLINE X-ray binaries Accretion regimes in neutron stars
Microquasars and their multifrequency emission
Black hole states and different types of jets (correlations)
Accretion/ejection and jet formation (propagation and ISM)
The QPO and the mass scaling (?)
Mechanisms of jet formation (?)
Conclusions

3. X-RAY BINARIES
An X-ray binary is a binary system containing a compact object (either a neutron star or a stellar-mass black hole) accreting matter from the companion star. The accreted matter carries angular momentum and on its way to the compact object usually forms an accretion disk, responsible for the X-ray emission. A total of 280 X-ray binaries are known (Liu et al. 2000, 2001).
High Mass X-ray Binaries (HMXBs). Optical companion with spectral type O or B. Mass transfer via decretion disk (Be stars) or via strong wind or Roche-lobe overflow (OB SG) and SFXT INTEGRAL. There are 131 known HMXBs.
Low Mass X-ray Binaries (LMXBs). Optical companion with spectral type later than B. Mass transfer via Roche-lobe overflow. 149 known LMXBs.

4. 131
149
Radio Emitting X-ray Binaries (REXBs) are X-ray binaries that display radio emission, interpreted as synchrotron radiation. Around 43 of the known X-ray binaries (15%) are REXBs, including 8 (persistent) HMXBs and 35 (transient) LMXBs. Abundances:
Total Galaxy No X-ray pulsars
HMXBs 8/131 ( 6%) 8/86 ( 9%) 8/37 (22%)
LMXBs 35/149 (23%) 35/147 (24%) 34/142 (24%)

5. ACCRETION REGIMES IN NEUTRONS STARS
Accretion radius (Bondi & Hoyle 1944): ra=4GMXvrel2 (impact parameter).
Magnetospheric radius rm: B(rm)2/8p=r(rm)v(rm)2 (magnetic field pressure=ram pressure).
Co-rotation radius: rc=(GMXPs2/4p2)1/3 (radius with Keplerian velocity and period Ps).
1. Direct wind accretion:
ra>rm and rc>rm
2. Centrifugal inhibition of accretion (propeller):
rc<rm<ra
3. Magnetic inhibition of accretion (solar wind):
rm>ra
4. Radio pulsar inhibition of accretion for (ejector): Ps<<1 s.
(Stella et al. 1986, ApJ, 308, 669)
rm rc ra

6. MICROQUASARS REXBs displaying relativistic radio jets.
Compact object may be a Neutron Star or a Black Hole (BH).
In BH, the length and time scales are proportional to
the mass, M.
The maximum color temperature of the accretion disk is Tcol  2107 M1/4.
(Mirabel & Rodríguez 1998)

7. MICROQUASARS : ARTIST’S VIEW

8. MULTIFREQUENCY EMISSION IN MICROQUASARS
Adapted from Chaty (1998, Ph.D. Thesis)
Compacts jets
Radio  IR
 X?
 gamma?
(synchrotron)
Donor star
IR  UV
(thermal)
Disc
+ corona ?
X  IR
therm + non therm
Wind
Visible  radio
(free-free) M •
Large scale ejection
Radio & X
gamma?
Interaction with environment
Dust ?
IR  mm
(thermal)

9. BLACK HOLE STATES AND DIFFERENT TYPES OF JETS
Black holes display different X-ray spectral states:
Low/hard state (a.k.a. power-law state).
High/soft state (a.k.a. thermal-dominant state).
Fender, Corbel, et al. (1999)
Low/Hard
High/Soft
Grebenev et al. (1993)

10. BLACK HOLE STATES AND DIFFERENT TYPES OF JETS
Black holes 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)

11. COMPACTS JETS: radio
Observations : image in radio or spectrum: radio flat
Fuchs et al. (2003)
Dhawan et al. (2000)
flat spectrum
GRS
GRS
flat or inverted spectrum model:
conical jet  max  1/Rmin
shock accelerated e--
emission = optically thick
synchrotron from radio  IR
Falcke et al. (2002)

12. COMPACTS JETS : X-rays  low/ hard state synchrotron emission :
Corbel & Fender (2002)
GX 339-4
 low/ hard state
synchrotron emission :
radio  IR  X ?
Optically thin Synchrotron in X-rays ?
Inverted spectrum
Corbel et al. (2003)
GX 339-4
radio – X-ray correlation: Frad  FX+0.7
over more than 3 decades in flux
 Universal law ?
ex: V404 Cyg, XTE J
  < 10
compact jet model can account for
the slope by only varying the jet power
other possibility : Inverse Compton of the soft photons by e-- from the jet basis

13. Gallo et al. (2003) found a correlation between radio and X-ray flux for Black Holes in the low/hard state. If the X-rays not beamed, then the Lorentz factors of the compact radio jets should be smaller than 2 to account for the small scattering of the correlation.

14. VLBA images of GRS 1915+105 reveal an asymmetric compact jet.
24 March
2.0 cm cm

15. VLBA images of GRS 1915+105 reveal an asymmetric compact jet.
24 March
2.0 cm cm
2 April
2.0 cm cm

16. VLBA images of GRS 1915+105 reveal an asymmetric compact jet.
24 March
2.0 cm cm
2 April
2.0 cm cm
19 April
2.0 cm cm

17. VLBA images of GRS 1915+105 reveal an asymmetric compact jet.
We infer b= , G<1.1, compatible with the above ideas (Ribó et al. 2004).
24 March
2.0 cm cm
2 April
2.0 cm cm
19 April
2.0 cm cm

18. The X-ray nova SWIFT J , observed during a low/hard state X-ray outburst in August 2005, does not fit in the correlation (Cadolle Bel et al. 2006).
10 kpc
5 kpc
1 kpc

19. ISOLATED (SUPERLUMINAL) EJECTIONS
 same Lorentz factor as in Quasars :  ~ 5-10
VLBI at 22 GHz ~ 1,3 cm
VLA at 3,5 cm
~ arcsec. scale
~ milliarcsec. scale
Mirabel & Rodríguez (1994)
Move on the plane of the sky ~103 times faster
Jets are two-sided (allow to solve equations  max. distance)
Advantage of AGN at <100 Mpc: collimation at Rsh (M87, Junor et al. 1999)

20. VARIABILITY: accretion / ejection coupling
Chaty (1998), Mirabel et al. (1998)
Cycles of 30 minutes in GRS :
Ejections after an X-ray dip
Disappearance / refilling of the internal part of the disc ?
Transient ejections during state changes

21. SUMMARY ABOUT JETS… state transition low/hard state quiescence
off states
high/soft state
Fender, Belloni & Gallo (2004)

22. XTE J1550-564 : LARGE SCALE X-RAY JETS !
Related to the brief flare of Sept. 1998
Discovery of X-ray sources associated with the radio lobes
Moving eastern source
Alignment + proper motion
First detection of moving relativistic X-ray jets !
Corbel et al. (2002)
evidence for gradual deceleration
radio-X-ray spectrum: compatible with synchrotron emission from the same e- distribution
external shocks with denser medium?
 Particle acceleration, to TeV ?
Chandra images keV
23 arcsec 
Also the source H

23. Jet-blown ring around Cygnus X-1, at the tail of the HII nebula Sh2-101 (Gallo et al. 2005). In analogy with extragalactic jet sources, the ring could be the result of a strong shock that develops at the location where the pressure exerted by the collimated jet, shown in the inset, is balanced by the ISM.
Assuming minimum energy conditions, this yields an expected lobe synchrotron surface brightness more than 150 times brighter than the observed ring: either the system is far from equipartition, or the most of the energy is stored in non-radiating particles, presumably baryons. 8'

24. LS 5039: from radio and GeV emission from EGRET (Paredes et al
LS 5039: from radio and GeV emission from EGRET (Paredes et al. 2000) to VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).

25. LS 5039: from radio and GeV emission from EGRET (Paredes et al
LS 5039: from radio and GeV emission from EGRET (Paredes et al. 2000) to VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).

26. LS 5039: from radio and GeV emission from EGRET (Paredes et al
LS 5039: from radio and GeV emission from EGRET (Paredes et al. 2000) to VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).

27. LS 5039: from radio and GeV emission from EGRET (Paredes et al
LS 5039: from radio and GeV emission from EGRET (Paredes et al. 2000) to VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).

28. LS 5039: from radio and GeV emission from EGRET (Paredes et al
LS 5039: from radio and GeV emission from EGRET (Paredes et al. 2000) to VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).

29. LS 5039: from radio and GeV emission from EGRET (Paredes et al
LS 5039: from radio and GeV emission from EGRET (Paredes et al. 2000) to VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).

30. LS 5039: from radio and GeV emission from EGRET (Paredes et al
LS 5039: from radio and GeV emission from EGRET (Paredes et al. 2000) to VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).

31. THE QPO AND THE MASS SCALING
Quasi Periodic Oscillations (QPOs) of X-ray count rates in X-ray binaries can be of low (Hz) or high frequency (kHz). The kHz QPOs sometimes come in pairs with a 3:2 ratio. The frequency of the upper kHz QPO seems to be correlated with 1/M for 3 microquasars (McClintock & Remillard 2003).
In the context of non-linear resonances between the two epicyclic frequencies in the inner regions of the accretion disc (Kluzniak & Abramowicz 2000), there is a good agreement with the 17 min period of Sgr A* (Genzel et al. 2003) or the 19:12 min pair (Aschenbach et al. 2004). This could allow us to unveil the mass of ultraluminous X-ray sources (Abramowicz et al. 2004).

32. MECHANISMS OF JET FORMATION
Energy and angular momentum can be extracted from a rotating black hole by a purely electromagnetic mechanism (Blandford & Znajek 1977).
Angular momentum is removed magnetically from an accretion disk by field lines that leave the disk surface, and is eventually carried off in a jet moving perpendicular to the disk (Blandford & Payne 1982).

33. Magnetohydrodynamic simulations show a well-defined jet that extracts energy from a rotating black hole. If plasma near the black hole is threaded by large-scale magnetic flux, it will rotate with respect to asymptotic infinity, creating large magnetic stresses. These stresses are released as a relativistic jet at the expense of black hole rotational energy. The physics of the jet initiation in the simulations is described by the theory of black hole gravitohydromagnetics. (Semenov et al. 2004).

34. CONCLUSIONS
X-ray binaries show relativistic jets from AU to pc scales.
They allow us to study the coupling between accretion and ejection processes on timescales much shorter than in quasars.
Extended jets show evidence for external shocks capable of accelerating electrons up to energies of several TeV. They are also able to blow huge structures and give us clues on their composition and energy balance.
The microquasar LS 5039 shows a SED extending up to the TeV range. Particle acceleration, gamma-gamma absorption, etc. New laboratories.
Timing of accretion disk QPOs can reveal the central mass of the black hole and maybe solve the ULX enigma.
There is no consensus on the mechanisms of jet formation. Kerr BHs can be effective, but there are neutron stars showing relativistic jets as well.