Transcript Document

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
1.
X-ray binaries
2.
Accretion regimes in neutron stars
3.
Microquasars and their multifrequency emission
4.
Black hole states and different types of jets (correlations)
5.
Accretion/ejection and jet formation (propagation and ISM)
6.
The QPO and the mass scaling (?)
7.
Mechanisms of jet formation (?)
8.
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 and Low Mass X-Ray Binary Systems
 HMXB : companion mass M2 > M
 Luminous, young, early type (O, B)
 Stellar Wind fed systems
 LMXB : companion mass M2  M
 Faint, old, late spectral type (K, M)
 Roche-Lobe / Disk fed systems
High Mass X-ray Binaries (HMXBs). Optical companion with spectral type O
or B. Mass transfer
viaMASS
decretion
disk (Be stars) or via strong wind or RocheDYNAMICAL
ESTIMATE
lobe overflow (OB
SG)
andfrom
SFXT
There are 131 known HMXBs.
 Orbital
parameter
measures INTEGRAL.
of
GRS 1915+105
Doppler shifts of Optical or IR lines/bands
 Derived Mass Function
f (M) = 9.5 M
f (M) = (M1cos i)3 / (M1 + M2)2  M1
can
provide estimate of Compact Object Mass
Low Mass X-ray Binaries (LMXBs). Optical companion with spectral type
later than B. Mass
transfer via Roche-lobe overflow. 149 known LMXBs.
Masses larger than 3 M must imply BH
(Greiner et al 01)

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).
rm rc ra
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)
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)
MICROQUASARS : ARTIST’S VIEW
MULTIFREQUENCY EMISSION IN MICROQUASARS
Adapted from Chaty (1998, Ph.D. Thesis)
• Donor star
IR  UV
(thermal)
• Wind
Visible  radio
(free-free)
•
M
• Dust ?
IR  mm
(thermal)
• Compacts jets
Radio  IR
 X?
 gamma?
(synchrotron)
• Disc
+ corona ?
X  IR
therm + non
therm
• Large scale
ejection
Radio & X
gamma?
Interaction with
environment
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).
High/Soft
Low/Hard
Grebenev et al. (1993)
Fender, Corbel, et al. (1999)
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
Corbel & Fender (2002)
GX 339-4
 low/ hard state
• synchrotron emission :
radio  IR  X ?
Inverted spectrum
Optically thin Synchrotron in X-rays ?
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
2.0 cm
2 April
3.6 cm
VLBA images of GRS 1915+105 reveal an asymmetric compact jet.
24 March
2.0 cm
3.6 cm
2.0 cm
2 April
3.6 cm
2.0 cm
19 April
3.6 cm
VLBA images of GRS 1915+105 reveal an asymmetric compact jet.
24 March
2.0 cm
3.6 cm
2.0 cm
2 April
3.6 cm
2.0 cm
19 April
3.6 cm
We infer b=0.2-0.4, <1.1, compatible with the above ideas (Ribó et al. 2004).
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
•
•
•
~103
Mirabel & Rodríguez (1994)
Move on the plane of the sky
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 !
•
Discovery of X-ray sources
associated with the radio lobes
Moving eastern source
•
Alignment + proper motion
Chandra images 0.3 - 8 keV
23 arcsec
Related to the brief flare of Sept. 1998
First detection of moving
relativistic X-ray jets !
evidence for gradual deceleration
• radio-X-ray spectrum: compatible with
synchrotron emission from the same edistribution
•
external shocks with denser medium?
 Particle acceleration, to TeV ?
•
Corbel et al. (2002)
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.
8'
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.
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. 2000) to
VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).
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. 2000) to
VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).
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. 2000) to
VHE gamma rays, TeV, with HESS (Aharonian et al. 2005).
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.