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The X-ray Universe 2008, Granada, May 27-30 2008

A Jet-Emitting Disk model for the A Jet-Emitting Disk model for the microquasar broad band microquasar broad band

emissionemissionG. HenriG. Henri

Coll. P.O Petrucci, J. Ferreira, C. FoellmiColl. P.O Petrucci, J. Ferreira, C. FoellmiLaboratoire d ’Astrophysique de Grenoble, FranceLaboratoire d ’Astrophysique de Grenoble, France


Accretion and ejectionAccretion and ejection

X-ray binaries show strong spectral variability

Low-hard

•hot corona

•disk emission weak or absent

High soft

•disk-dominated

•non thermal power-law

Grove et al ‘98


Hysteresis cycleHysteresis cycle

.

Hardness-intensity plots show characteristic hysteresis cycles

At least two parameters : M and…… ?.

e.g. GX339-4 Belloni et al. ‘05


« Jet-line » flaring events« Jet-line » flaring events

Compact (optically thick) jets associated with low-hard states

Relativistic flares (optically thin) generally associated with luminous « Very High states » when crossing a « jet line » (Fender et al. ‘04)

Dhawan et al. 2000

(Mirabel & Rodriguez 1994)superluminal velocities

e.g. GRS 1915+105


Spectral transitions Spectral transitions

GRS 1915+105 .

Flaring events associated with the disappearance of the disk emission and hardening spectra

e.g. Mirabel et al., 1998

Correlations betwen X and radio

(Corbel et al. 2003; Gallo et al. 2004…


A Jet Emitting Disk model :general A Jet Emitting Disk model :general picturepicture

Inner accretion disk emitting a Jet by a MHD centrifugal process

Outer Standard accretion disk (SAD)

Flaring relativistic jets explained by pair creation events (~ AGNs)

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Characteristic transition radius rj


The MHD Jet Emitting DiskThe MHD Jet Emitting Disk

Baryonic jet can be emitted from the accretion disk through MHD mechanism (Blandford-Payne 1982, Ferreira et al., 1997, 2004)

B field extracts angular momentum and power from the JED (Jet Emitting Disk)

Powerful, but only mildly relativistic (0,5 - 0,9 c)


EnergeticsEnergetics

Jets extract a fair part of the accretion energy

€

PjetPacc

= qΛ

1+ ΛWhere

€

Λ = MHD torqueViscous torque

~hr

⎛ ⎝ ⎜

⎞ ⎠ ⎟−1

~ 10 to100

€

q ~ 0.5 to1

Jet power -> underluminous disks can « apparently » disappear~ ADAF but energy channelled in jets, not below the horizon

Stable solutions can exist only close to equipartition

If magnetization parameter

€

μ = pBpgas + prad

= 0.1 to1


Magnetic transitionsMagnetic transitions

In the outer standard disc

€

Bz ∝ r−3/2

ptot ∝ r−1/2

(Jet Emitting Disc)(Standard Accretion Disc)

SAD JED when µ ~ 1

JED SAD when µ ~ 0.1

Pmag/Ptot

rrtr

1

SADJED

0.1

ASSUMPTIONS

µ if r

In the inner JED µ ~ Constant (adjusted by the MHD structure)


Hysteresis cyclesHysteresis cycles

Petrucci et al, MNRAS 2008


JED structureJED structure

Thermal JED structure must be determined self-consistently

Simple approximations * isothermal vertical structure

* cooling processes : bremsstrahlung, synchrotron, comptonization.

* heating process = part of accretion energy

Non-linear dependance of heating on

€

Λ ~hr

⎛ ⎝ ⎜

⎞ ⎠ ⎟−1

~vKcs

Balance solved numerically


Multivalued solutionsMultivalued solutions

Bremsstr. Bremsstr.Synchr.

Synchr.

Compt.

Cold solution : standard disk-likeHot solution : corona-like

Qheat

Qheat


Radiative transitions


Example of SED

Depends on radial structure, complicated with multivalued solutions and variability…

still in progress….

Spectral Energy Distributions


Ejection of relativistic components

In situ generation of pair plasma in the inner MHD funnel (H.& Pelletier 91, Marcowith et al. ‘95)

Produced through gamma-ray emission• Injection of some relativistic particles• X-ray and gamma-ray emission by IC

and/or SSC• annihilation forms new pairs• Continuous reacceleration by MHD

turbulence necessary for a pair runaway to develop.

• Limited by the free energy available: saturation must occur at some point.

• Intermittent production possible and even probable !

hvs X,e+e-

2-flow model for AGNs


Time dependant flaresTime dependant flares

See Boutelier’s poster (#G4) for the PKS2155-304 case

TeV flux

Pair production

X-ray/optical


• Density n0(r)• Temperature T0(r)

+ n(r,t)+ T(r,t)

rin

rtr

Hard X

UV/Soft X

Generation of low frequency QPO


Monte Carlo SimulationsMonte Carlo Simulations

• Vertical optical 0 = 1.4• Temperature T0=100 keV• rtr=50 rg, cs=(kT0/mp)0.5~0.01c

rin

rtr

SED

PDS resonances

cs/rtr

White noise

Energy (keV)

RM

S

Cabanac PhD thesis


ConclusionsConclusions

A magnetically dominated, inner jet emitting disk can provide a good framework to understand

•Spectral changes

•Correlation X-radio

•Variability, QPO

Complicated interplay between accretion rate, magnetic transitions , radiative instabilities .. (but reality IS complex ! )

•Work in progress to compare with detailed spectra and variability.