Jet Collimation

Jet Acceleration

Nakamura & Asada (2013)

Park et al. 2019

Jongho Park (ASIAA) In collaboration withKazuhiro Hada, Motoki Kino, Masanori Nakamura, and EAVN AGN SWG

Highly Collimated and Relativistic Jets of AGNs
3C 279~5c~1 Mpc

Highly collimated, very narrow jets
Superluminal motions

Acceleration and Collimation of AGN Jets

Jet Acceleration & Collimation: a “pipeline” to produce highly collimated relativistic AGN jets

The MHD models of jet acceleration
Magnetic Jet Acceleration ModelVlahakis 2015

‘Differential Collimation’ of Poloidal Field Lines: Inner fields are more collimated than outer lines→ Jet Collimation & Acceleration are intimately related to each other.

The MHD models of jet acceleration
Magnetic Jet Acceleration ModelVlahakis 2015

‘Differential Collimation’ of Poloidal Field Lines: Inner fields are more collimated than outer lines→ Jet Collimation & Acceleration are intimately related to each other.

The MHD models of jet acceleration
Magnetic Jet Acceleration Model

Vlahakis 2015

‘Differential Collimation’ of Poloidal Field Lines: Inner fields are more collimated than outer lines→ Jet Collimation & Acceleration are intimately related to each other.

The MHD models of jet acceleration
Magnetic Jet Acceleration ModelVlahakis 2015

‘Differential Collimation’ of Poloidal Field Lines: Inner fields are more collimated than outer lines→ Jet Collimation & Acceleration are intimately related to each other.

Jet Collimation in nearby AGN jets

Asada & Nakamura (2012)

Hada et al. (2013)
Nakamura et al. (2018)

M87

Jet Collimation in nearby AGN jets

NGC 4261
Nakahara+ (2018)

NGC 6251
Tseng+ (2016)

1H 0323+34
Hada+ (2018)

1928+738
K. Lee+ in prep.

Jet Collimation in M87

Asada & Nakamura (2012)

Nakamura et al. (2018)

Is the M87 jet accelerated to relativistic speeds in thecollimation zone?

Jet Acceleration in M87
Jet Collimation

Jet Acceleration?

Asada & Nakamura (2012)
Nakamura & Asada (2013)

Jet Acceleration in M87
Jet Collimation

Asada & Nakamura (2012)
Nakamura & Asada (2013)

Jet Acceleration

Jet Acceleration in M87
Jet Collimation

Jet Acceleration

HST-1(near the Bondi radius)

HST-1

HST-1

Asada & Nakamura (2012)
Nakamura & Asada (2013)
Biretta+ (1999), HST opticalJet Acceleration in M87
Jet Collimation

Jet Acceleration

HST-1(near the Bondi radius)

HST-1

HST-1
Hada+ (2016)

Asada & Nakamura (2012)
Nakamura & Asada (2013)
Biretta+ (1999), HST opticalKim+ (2018)

Kinematics of the M87 jet : 1. modelfit
The MOJAVE monitoring program
VLBA 15 GHz over ~10 years
Sampling Interval : ~6 months‘modelfit’ components withcircular Gaussian brightness distributions

Kovalev et al. (2007)at <~ 20 mas

Kinematics of the M87 jet : 1. modelfit“Knots” described by circular
Gaussian component

Modelfit works very well for most blazars
whose jets consist of several “knots”

Park et al. (2019c)

Kinematics of the M87 jet : 1. modelfit
The MOJAVE monitoring program
VLBA 15 GHz over ~10 years
Sampling Interval : ~6 months‘modelfit’ components withcircular Gaussian brightness distributions

Kovalev et al. (2007)at <~ 20 mas

Kinematics of the M87 jet : 1. modelfit
EVN observations
EVN 1.6 GHz in three epochs
Sampling Interval : ~1 year

‘modelfit’ components withcircular Gaussian brightness distributions

Asada et al. (2014)

Kinematics of the M87 jet : 1. modelfit

Kinematics of the M87 jet : 1. modelfit

Kinematics of the M87 jet : 1. modelfit?

Kinematics of the M87 jet : 2. Visual Inspection
VLBA 43/86 GHz (~2 weeks)

VLBA 43 GHz (~3 weeks)

Walker et al. (2018)

Identify each locally brightened jet region indifferent epochs by ‘Visual Inspection’Hada et al. (2016)

Kinematics of the M87 jet : 2. Visual Inspection
VLBA 43/86 GHz (~2 weeks)

VLBA 43 GHz (~3 weeks)

Walker et al. (2018)

Identify each locally brightened jet region indifferent epochs by ‘Visual Inspection’Hada et al. (2016)

Kinematics of the M87 jet : 2. Visual Inspection

Kinematics of the M87 jet : 2. Visual Inspection

Kinematics of the M87 jet : 2. Visual Inspection

Kinematics of the M87 jet : 3. WISE
VLBA 43 GHz (~3 weeks)

Mertens et al. (2016)

WISE (Wavelet-based Image Segmentation and Evaluation)
Wavelet Transformation(Detect brightness patterns)

2D Cross-Correlation(Kinematics)

Kinematics of the M87 jet : 3. WISE
VLBA 43 GHz (~3 weeks)

Mertens et al. (2016)

WISE (Wavelet-based Image Segmentation and Evaluation)
Wavelet Transformation(Detect brightness patterns)

2D Cross-Correlation(Kinematics)

Kinematics of the M87 jet : 3. WISE

Kinematics of the M87 jet : 3. WISE

Kinematics of the M87 jet : 3. WISE

Both fast and slow
motions
V-stratification?

Kinematics of the M87 jet : 4. Jet-to-counterjet brightness ratio
VLBA 43 GHz

Walker et al. (2018)

The brightness difference : due to the Doppler boosting/deboostingKinematics of the M87 jet : 4. Jet-to-counterjet brightness ratio

Kinematics of the M87 jet : 4. Jet-to-counterjet brightness ratio

Kinematics of the M87 jet : 4. Jet-to-counterjet brightness ratio?
?

KVN and VERA Array (KaVA)― Good Sensitivity.
― Reasonably good angular resolution.
― Good uv-coverage.
→ KaVA Large Program : Observations of M87 ‘biweekly’ at 22 & 43 GHz(~10 epochs per year).

KVN and VERA Array (KaVA)― Good Sensitivity.
― Reasonably good angular resolution.
― Good uv-coverage.
→ KaVA Large Program : Observations of M87 ‘biweekly’ at 22 & 43 GHz(~10 epochs per year).

KVN and VERA Array (KaVA) → The East Asian VLBI Network (EAVN)

An+ (2018)

KaVA observations in 2016 : 1. modelfit
the KaVA Large Program (~2 weeks)

22 GHz43 GHzKaVA observations in 2016 : 1. modelfit
the KaVA Large Program (~2 weeks)

22 GHz43 GHzKaVA observations in 2016 : 2. Visual Inspection
the KaVA Large Program (~2 weeks)

22 GHz43 GHzKaVA observations in 2016 : 2. Visual Inspection
the KaVA Large Program (~2 weeks)

Modelfit with point-sources andgroup them

22 GHz43 GHzKaVA observations in 2016 : 3. WISE
the KaVA Large Program (~2 weeks)

Kinematics of the M87 jet : Results

Kinematics of the M87 jet : Results

Kinematics of the M87 jet : Results

Kinematics of the M87 jet : Results?
?

VLBA archival data analysis
VLBA Archival data analysis
VLBA 1.7 GHz over ~4 years
Sampling Interval : ~2 months

Compared to the EVN observations by Asada et al...
― Improved Sensitivity (by a factor of > a few).
― Improved Angular Resolution (by a factor of >2).
― Denser Monitoring (Interval : ~2 months).

VLBA archival data analysis : 1. modelfit

VLBA archival data analysis : 2. WISE

Kinematics of the M87 jet : Results

Kinematics of the M87 jet : Results

Kinematics of the M87 jet : Results

Jet Acceleration in M87
Jet Collimation

Nakamura & Asada (2013)

Jet Acceleration

Jet Acceleration in M87
Jet Collimation

Nakamura & Asada (2013)

Jet Acceleration

Jet Acceleration in M87
Jet Collimation

Jet Acceleration

Jet Collimation

Jet Acceleration

Nakamura & Asada (2013)

We studied jet acceleration of M87 with KaVA and VLBA data and our results suggest a
Gradual jet acceleration in THE SAME REGION AS THE COLLIMATION ZONE.

→ Supports the magnetic jet acceleration model.

Jet Acceleration in M87
Jet Collimation

Jet Acceleration

Thanks to the EAVN’s extensive
high cadence monitoring

Jet Collimation

Jet Acceleration

Nakamura & Asada (2013)

We studied jet acceleration of M87 with KaVA and VLBA data and our results suggest a
Gradual jet acceleration in THE SAME REGION AS THE COLLIMATION ZONE.

→ Supports the magnetic jet acceleration model.

Discussion: Origin of the stationary features in the jet?
Reid+(1989)

Asada+(2014)~165 mas~65 mas~20 mas~65 masSeveral ‘apparently stationary’ features exist in the jet at ~20, ~65, and ~165 mas.

Discussion: Origin of the stationary features in the jet?
Reid+(1989)~20 mas~65 mas ~165 mas

Asada+(2014)~65 masSeveral ‘apparently stationary’ features exist in the jet at ~20, ~65, and ~165 mas.

Discussion: Origin of the stationary features in the jet?

~20 mas~165 mas

Several ‘apparently stationary’ features exist in the jet at ~20, ~65, and ~165 mas.
→ They may not be ‘physically’ stationary but result from the re-brightening of the jet(regions of particle acceleration? Or local Doppler boosting enhancement?).

Discussion: Slow Jet Acceleration― The jet motion is not as fast as what GRMHD simulations showed on < a few hundreds Rs.

Discussion: Slow Jet Acceleration― The jet motion is not as fast as what GRMHD simulations showed on < a few hundreds Rs.

Discussion: Slow Jet Acceleration

Local Hot spots: VLBI speeds

Underlying Flows: Jet Bulk Speeds

Kinematics of the M87 jet : 4. Jet-to-counterjet brightness ratio
VLBA 43 GHz

Walker et al. (2018)

The brightness difference : due to the Doppler boosting/deboostingKinematics of the M87 jet : 4. Jet-to-counterjet brightness ratio

Kinematics of the M87 jet : 4. Jet-to-counterjet brightness ratio

Discussion: Slow Jet Acceleration― The jet motion is not as fast as what GRMHD simulations showed on < a few hundreds Rs.

Discussion: Slow Jet Acceleration― The jet motion is not as fast as what the models of highly magnetized jet predict.

Discussion: Slow Jet Acceleration

Jet Magnetization

Differential Collimationof Poloidal Fields

Efficient Jet Acceleration― The jet motion is not as fast as what the models of highly magnetized jet predict.

Discussion: Slow Jet Acceleration

Energy ‘Budget’

Jet Magnetization

Differential Collimationof Poloidal Fields

Efficient Jet Acceleration― The jet motion is not as fast as what the models of highly magnetized jet predict.

Discussion: Slow Jet Acceleration

Energy ‘Budget’

Jet Magnetization

Acceleration Efficiency

Differential Collimationof Poloidal Fields

Efficient Jet Acceleration― The jet motion is not as fast as what the models of highly magnetized jet predict.

Discussion: Slow Jet Acceleration

Energy ‘Budget’

Jet Magnetization

Acceleration Efficiency

Differential Collimationof Poloidal Fields

Efficient Jet Acceleration― The jet motion is not as fast as what the models of highly magnetized jet predict.

Bulk Lorentz Factor

Discussion: Slow Jet Acceleration

Mertens+ (2016)

Bulk Lorentz Factor

Discussion: Slow Jet Acceleration

Mertens+ (2016)

Bulk Lorentz Factor

Discussion: Slow Jet Acceleration

Mertens+ (2016)

Bulk Lorentz Factor

Discussion: Slow Jet Acceleration

Saturation due to notenough jet magnetization

Mertens+ (2016)

Discussion: Slow Jet Acceleration
The highly magnetized jet base of M87

Kim+ (2018)
Kino+ (2015)…from the observed
core brightness temperature

Discussion: Slow Jet Acceleration

Energy ‘Budget’

Jet Magnetization

Acceleration Efficiency

Differential Collimationof Poloidal Fields

Efficient Jet Acceleration― The jet motion is not as fast as what the models of highly magnetized jet predict.

Discussion: Slow Jet Acceleration

Nakamura+ (2018)

Recent GRMHD Simulations

Concentrated ‘Core’of field lines

Tchekhovskoy+(2009), FFE model

The Poynting flux conversion may not be as efficient as in an ideal case.

Discussion: Slow Jet Acceleration
Chatterjee+ (2019)

JetJetWindWinds

Sadowski+ (2013)

Hot accretion flowsAdditional mass entrainment from the outer slower winds?

Discussion: Velocity Stratification― At a given distance bin, a wide range of speed is observed at all distances we probed.

Discussion: Velocity Stratification― At a given distance bin, a wide range of speed is observed at all distances we probed.

Discussion: Velocity Stratification

Mertens+ (2016)

Discussion: Velocity Stratification

Colors : Γ distribution

Komissarov+ (2009)

SRMHD Simulations

GRMHD Simulations

Nakamura+ (2018)― At a given distance bin, a wide range of speed is observed at all distances we probed.
― The observed jet may consist of ‘multiple streamlines’ following different acceleration
profiles, naturally resulting in the lateral velocity stratification.

Discussion 3. Velocity Stratification

1.
2.

Instabilities
Multiplestreamlines― Whether the ‘lower envelope’ shows an acceleration feature or not would
be important to test these scenarios.

Discussion 3. Velocity Stratification

1.
2.

Instabilities
Multiplestreamlines

Lower Envelope
Acceleration?

― Whether the ‘lower envelope’ shows an acceleration feature or not would
be important to test these scenarios.

Conclusions (Park et al. 2019b, ApJ, 887, 147)
― We studied the jet kinematics by using the densely monitored data observed withKaVA at 22 and 43 GHz and using archival VLBA data at 1.7 GHz.
― We found that the M87 jet is gradually accelerated to relativistic speeds in thesame region as the jet collimation zone, as predicted by MHD models.

Jet Collimation

Nakamura & Asada (2013)

Jet Acceleration

Backup Slides

Jet collimation by an external confining medium
Lorentz force :collimating jet: ideal MHD approximation
When relativistic→ electric force and Lorentz force
become comparable

Electric force : de-collimating jet

Or, jet inertia is too high to bend its
direction in the comoving frame.

Jets must be confined (or collimated) by an external medium!
Jet Collimation
An External Medium
Jet Acceleration

Mizuno+ (2007)
Weak B field

Strong B field