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
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
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.
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 280 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%)
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
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 2107 M1/4. (Mirabel & Rodríguez 1998)
MICROQUASARS : ARTIST’S VIEW
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)
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)
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)
COMPACTS JETS: radio Observations : image in radio or spectrum: radio flat Fuchs et al. (2003) Dhawan et al. (2000) flat spectrum GRS 1915+105 GRS 1915+105 flat or inverted spectrum model: conical jet max 1/Rmin shock accelerated e-- emission = optically thick synchrotron from radio IR Falcke et al. (2002)
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 J1118+480 < 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
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.
VLBA images of GRS 1915+105 reveal an asymmetric compact jet. 24 March 2.0 cm 3.6 cm
VLBA images of GRS 1915+105 reveal an asymmetric compact jet. 24 March 2.0 cm 3.6 cm 2 April 2.0 cm 3.6 cm
VLBA images of GRS 1915+105 reveal an asymmetric compact jet. 24 March 2.0 cm 3.6 cm 2 April 2.0 cm 3.6 cm 19 April 2.0 cm 3.6 cm
VLBA images of GRS 1915+105 reveal an asymmetric compact jet. We infer b=0.2-0.4, G<1.1, compatible with the above ideas (Ribó et al. 2004). 24 March 2.0 cm 3.6 cm 2 April 2.0 cm 3.6 cm 19 April 2.0 cm 3.6 cm
The X-ray nova SWIFT J1753.5-0127, 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
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 30-100 Rsh (M87, Junor et al. 1999)
VARIABILITY: accretion / ejection coupling Chaty (1998), Mirabel et al. (1998) Cycles of 30 minutes in GRS 1915+105: Ejections after an X-ray dip Disappearance / refilling of the internal part of the disc ? Transient ejections during state changes
SUMMARY ABOUT JETS… state transition low/hard state quiescence off states high/soft state Fender, Belloni & Gallo (2004)
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 0.3 - 8 keV 23 arcsec Also the source H 1743-322
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'
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).
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).
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).
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).
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).
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).
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).
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).
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).
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).
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.