Black hole accretion and jet ejection

James Miller-Jones

Collaborators: Greg Sivakoff, the JACPOT XRB collaboration, Tom Russell, Peter Jonker, Dave Russell

Email: james.miller-jones@curtin.edu.au

Overview

• Disc-jet coupling in X-ray binaries

• Hard states:

– Compact jets– Radio/X-ray correlation

• Hard-to-soft transitions:

– Compact jets quenched– Launching of discrete ejecta

• Soft state quenching

– Role of a disc wind?

• Soft-to-hard transitions

– Compact jets re-established

Image credit: R Hynes

Image credit: R Hynes

The multiwavelength view of an XRB

Markoff (2007)

• Jets: IR, radio• Donor: IR,

optical• Disc: optical,

UV, X-rays• Corona: X-rays• Corona/jet

base: -rays?

Why study XRBs in the radio band?

• Band in which emission is dominated by the jets

• Probe of high-energy processes

• High-resolution imaging

– Resolve jet morphology evolving in real time– Jet collimation, propagation, energetics– Probe accretion-ejection coupling

• Astrometry

– Faint, persistent emission in hard/quiescent state– Model-independent parallax distances– Proper motions (formation mechanisms,

birthplaces)

Jet-disk coupling in accreting black holes

Fender, Belloni & Gallo (2004)

Bright

Faint

Disc-dominated Power-law dominated

Mirabel & Rodriguez (1994), Fender et al. (1999)

Dhawan et al. (2000)

Compact jets in the hard state

Fender, Belloni & Gallo (2004)

Bright

Faint

Disc-dominated Power-law dominated

Compact jets: spectra• Flat or slightly inverted spectra from radio through IR

• Overlapping SSA spectra, we see emission from optical depth 1 at each frequency

• Spectral break (typically mid-IR) provides radiative luminosity of jet

Fender et al. (2000)MAXI J1836-194

Dhawan et al. (2000)

GRS 1915+105

Compact jets: morphology

Cygnus X-1

MAXI J1836-194

• Jets directly resolved in 3 sources

• Inferred to exist in all hard-state systems

• Flat/inverted radio spectra

• Radio/X-ray correlation

Rushton et al. (2012)

Corbel et al. (2000)

GX 339-4

Compact jets: radio polarization

Cyg X-1

MAXI J1836-194

• Polarized emission probes B-field ordering and orientation

• Few percent polarization detected in 3 sources

• EVPA, B-field aligned with jet axis

The radio/X-ray correlation

• Non-linear correlation over 8 decades in Lx

Corbel et al. (2003)

Gallo et al. (2003)

Gallo et al. (2006)

The radio/X-ray correlation

• Lr Lx0.7

Corbel et al. (2003)

Gallo et al. (2003)

Gallo et al. (2006)

Universality?• Radio-quiet outliers falling well below correlation

Jonker et al. (2012)

Two tracks

• Clustering analysis shows evidence for two distinct clusters

• Bayesian regression of the two clusters shows different slopes

Gallo et al. (2012)

Gallo et al. (2012)

Efficient vs inefficient accretion?• Transition between radio-quiet and radio-loud branches

Coriat et al. (2011)

Efficient vs inefficient accretion?• Transition between radio-quiet and radio-loud branches

Ratti et al. (2012)

A mix of physical processes?• Steep slope: has to be radiatively efficient?

Lr Lx2.1

Transition period

Fender, Belloni & Gallo (2004)

Bright

Faint

Disc-dominated Power-law dominated

Transition

• X-ray emission rises

• X-ray hardness, fractional variability decrease

• Appearance of QPOs

• Compact jet quenching

• Major radio flare

• Launching of discrete ejecta

Miller-Jones et al. (2012)

H1743-322

The accretion-ejection connection

Spectral signatures of ejection

• Use VLBA proper motions to determine ejection date

• Does the “Unified Model’ hold?

– As far as we can tell– Additional radio quench phase

Miller-Jones et al. (2012)

Miller-Jones et al. (2012)

Timing signatures of ejection

• What happens in the accretion disc to cause the switch?

– X-ray spectral state transition– Type C QPOs disappear from power spectrum– Fractional rms variability drops

Miller-Jones et al. (2012)

The transient ejecta

• Note delay between derived ejection date and when transient jets appear

– Ejection precedes radio quenching

– Time for ejecta to become optically thin at radio frequencies?

– Time for internal shocks to form within the jet?

Miller-Jones et al. (2012)

Comparison of different outbursts

• Does the ejection always happen at the same hardness?

– No; different in two outbursts of the same source

Miller-Jones et al. (2012)

Comparison of different outbursts

• Jet ejecta have different speeds in the two outbursts

– Proper motions 3.7 ± 0.7, 3.3 ± 0.8 mas/d in 2009– Corresponds to 0.19<<0.28– Compare with 21.2 ± 1.4, 13.3 ± 0.6 mas/d in 2003 (after

deceleration)

• Black hole spin unlikely to have changed between outbursts: more likely to be mass accretion rate

• 2003 outburst significantly brighter

– Is jet speed correlated with outburst luminosity?

Quenched jets in the soft state

Fender, Belloni & Gallo (2004)

Bright

Faint

Disc-dominated Power-law dominated

Compact jet quenching

• Compact jets quenched in soft states

• Quenching factor >700 (Coriat et al. 2011)

• Quenching factor >330-810 (Russell et al. 2011)

• Possible difference with AGN (less quenching)

• Role played by disc winds? (see Neilsen talk)

Russell et al. (2011)

Jet reactivation

Fender, Belloni & Gallo (2004)

Bright

Faint

Disc-dominated Power-law dominated

Jet re-activation

• When do compact jets re-ignite in the radio band?

– On moving from HSS to HIMS

• No VLBA detection after main outburst; emission location unconfirmed

• OIR jets known to switch on only after return to LHS

• Gradual evolution of jet power?

• Remnant optically thin emission?

Miller-Jones et al. (2012)

Summary

• Compact jets ubiquitous in hard states of BH XRBs

• Magnetic fields oriented along jet axis

• Correlation between radio, X-ray emission

• Separate branches, with transition between them

• Different spectral slopes

• Jet ejection events correlate with X-ray spectral and timing changes

• Causal sequence not yet established

• Different outbursts have different jet speeds

• Quenching of radio emission in soft states (factor 102-103)

• Compact radio jets re-ignite on moving from HSS to HIMS