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Jet-Gas Interactions in Seyfert Galaxies. Mark Whittle (Virginia) David Rosario (Virginia) John Silverman (Virginia) Charlie Nelson (Drake) Andrew Wilson (Maryland). Outline. Brief review of : AGN & Jets & Emission lines Reasons to study jet-gas interactions (JGI)

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jet gas interactions in seyfert galaxies

Jet-Gas Interactions in Seyfert Galaxies

Mark Whittle (Virginia)

David Rosario (Virginia)

John Silverman (Virginia)

Charlie Nelson (Drake)

Andrew Wilson (Maryland)

outline
Outline
  • Brief review of :

AGN & Jets & Emission lines

Reasons to study jet-gas interactions (JGI)

  • Case study of Seyfert Galaxy : Mkn 78

Observations & data overview

Heuristic description of JGI

Ionization analysis

Dynamical analysis

active galaxies
Active Galaxies
  • All galaxies have nuclear black holes
  • Those currently accreting are “active”
  • Accretion energy released in two forms
a photons
A : Photons
  • Thermal & non-thermal processes
  • Broad SED : Optical / UV / X-ray
  • Large range in luminosity :

LINER  Seyfert  QSO

slide5

AGN Spectral Energy Distribution (SED)

Radio far-IR optical EUV X-ray

slide6

Seyferts

(NGC 4151)

Low Luminosity

Quasars

High Luminosity

b bipolar outflows jets
B : Bipolar Outflows (Jets)
  • Origin uncertain (MHD driven ?)
  • Velocity uncertain :
    • Some relativistic, others not
  • Content uncertain : (p+e- or e+e- ?)
    • Relativistic component : e- + B  radio
    • Other (thermal) components ?
  • Large luminosity range :
    • Radio loud (radio galaxies/QSRs)
    • Radio quiet (Seyferts/QSOs)
slide9

Seyfert Galaxy

Mkn 573

Flux ~ few mJy

Radio Quiet

Radio Galaxy

3C 296

Flux ~ few Jy

Radio Loud

slide10

Emission Lines

  • From ionized gas :
    • Te~ 104K, ne~ 102 – 109 cm-3
  • Ionization mechanism ?
    • Photoionization (yes)
    • Shock related (maybe with jets?)
  • Profiles reveal (Doppler) velocities
    • BLR (R ~ 10-2pc, V2~ GMBH/R)
    • NLR-1 (R ~ 1 kpc, V2~ GMbul/R)
    • NLR-2 (R ~ 1 kpc, V ~ jet related)
  • Nested emission line regions
    • BH << AD << BLR << NLR << Gal
  • r/c : min hr week 103 yr 104 yr
slide11

Why study JGI in Seyferts ?

  • Jet-gas interactions occur in many contexts
    • AGN (ISM/IGM)
    • Stellar jets (DMC/ISM)
    • Starburst winds (ISM/IGM)
  • Laboratory for astrophysical hydrodynamics
  • Seyfert ELRs allow important diagnostics
    • Gas mass, velocity, KE, momentum, pressure
    • Complements radio source pressure/energy
mkn 78 jet gas archetype
Mkn 78 : jet-gas archetype

Early ground based data suggest

prominent JGI :

  • Luminous triple radio source
  • Strong double [OIII] profile
  • FWHM >> gravitational velocities
need hst resolution
 Need HST resolution

Unfortunately, Mkn 78 is quite distant :

  • cz ~ 11,000 km/s  1 arcsec ~ 700pc
  • BT ~ 15.2 MB ~ -20.8
  • Dull looking early type galaxy
slide15

Mkn 78

KPNO 2.1m Red Continuum

30 arcsec

mkn 78 hst vla dataset
Mkn 78 : HST & VLA Dataset
  • VLA : 3.6cm 8hr map
  • HST images : (FOC, PC, STIS, NICMOS)
    • Continuum : UV/green/near-IR
    • Emission line : [OIII] 5007
  • HST spectra : (STIS, FOS)
    • 4 slits : good spatial coverage
    • 4 gratings : low resolution : UV & optical

high resolution : [OIII] 5007

slide17

Near IR

NICMOS F160W

arcsec

Optical

STIS CCD clear

Dust lane

slide18

[OIII] λ5007

arcsec

3.6cm radio

mkn 78 case study jet gas interactions
Mkn 78 Case Study :Jet-gas interactions
  • Heuristic description
  • Ionization study
  • Dynamical study
  • Jet properties
1 heuristic description
1. Heuristic Description
  • Inner W-knot

Jet ends & disrupts; some gas disturbance

?  DMC enters & disrupts flow; recent interaction

  • Eastern fan

Jet deflected; split lines; “blow-back” shape

?  Cloud inertia deflects jet (doesn’t destroy it)

?  Radial + lateral motion induced (±300 on 400)

?  Intermediate age : begun to disrupt cloud

  • Outer W-lobe

Components; complex velocity ; no bow shock

?  late stage; dispersing cloud remnants; leaky bubble

2 ionization study
2. Ionization Study

Low dispersion spectra  many line fluxes

Compare line ratios with :

  • Ionization models (U, Am/i , Shock)
  • Velocities (Vbulk & FWHM)
  • Location (radius)

4. Other things (radio/color/dust)

ionization mechanisms
Ionization mechanisms

Three basic contexts explored :

  • U – sequence : AGN photoionization
  • Am/i – sequence : AGN photoionization
  • Shock – sequence : shock ionization

Cartoon illustrates these 

slide28

1)U sequence

2) Am/i sequence

Neutral

Back

Optically

Thin clouds

Ionized

front

AGN

AGN

Optically

Thick Clouds

Only

Optically

Thick & Thin

Clouds

UV

UV

Ferland’s, CLOUDY

Binette et al : ‘96

Am/i = Am/Ai ~ 0.1 – 10

U = Ni/Ne ~ 10-2 – 10-3

3)Shock sequence

Vsh

shock

Collisionally ionized

& photo-ionized

post-shock gas

Auto-ionizing

Shocks

Photo-ionized

precursor

UV

Vsh = 100 – 800 km/s

Doptia & Sutherland : ‘95, ‘96, ‘03

line ratios vs models
Line ratios vs models
  • General excitation/ionization
  • Discriminators to separate Sh & U+Am/i
  • Discriminators to separate U & Am/i
  • [ [OI] 6300 anomalous line ]
  • [ Nuclear nitrogen enhancement ]
slide30

Excitation :

All models OK

U ~ 10-2 – 10-3

A ~ 30% – 90%

Sh ~ 500 – 300 km/s

U

Am/i

Sh

slide31

U

Discriminators 1

Trends follow U & A

Don’t follow shocks

Am/i

Sh

slide32

Discriminators 2

e.g. [NeV], HeII,

& [OIII]4363

U poor, favours Am/i

trend fits nicely

Note : weak [NeV]

in Mkn 78

requires new Am/i

U

Am/i

Sh

slide33

Ratios vs models : Summary

  • Clean results because enough data to show trends
  • Current shock models are excluded
  • Photoionization by the AGN dominates
  • Gas contains both optically thick & thin clouds

Now consider ratios vs gas velocity

slide34

Excitation vs FWHM

Excitation vs V –Vsys

Shock

Shock

Results summary 

slide35

Ratios vs velocity : Summary

  • Essentially no (v. weak) correlations :

 ionization conditions independent of velocity

2. Shock model predictions very poor

Now consider ratios vs radius

slide36

Excitation vs Radius

  • Radius :
  • Strong correlation
  •  photoionization
  • U drops ~ r –1

 density ~ r –1

  • [SII] difficult to confirm
  • Am/i drops with r
  •  more thin @ small r
final check uv luminosity
Final check : UV Luminosity
  • Check photoionization :
    • Can UV luminosity power emission lines ?
  • But UV is invisible/obscured ?!
  • Take FIR luminosity = reprocessed UV
    • LUV~ LFIR~ 4πd2FFIR~ 4πd2 [2.6S60+ S100]
  • Check :
    • LUV~ Lem ~ 10 x L5007as observed
    • U ~ NUV/ne~ 10-2.5as observed
3 dynamical study
3. Dynamical Study

To go beyond heuristic description :

  • Need physical properties
  • Aim to evaluate these throughout regions
  • First consider ionized gas
  • Then consider other components
slide39

Slit B : kinematic measurements

Peak Velocity

FWHM

-2 -1 0 +1 +2 +3

East Nuc West

slide40

Extinction

Density

Line flux

Mass

Momentum

KE

simple properties
Simple Properties

Three regions : Inner knot / East fan / West lobe

Region Age :

  • Age ~ size/velocity : ~ 0.4 / 4 / 8 Myr

Ionized gas :

  • Mass : ~ 0.4 / 1.0 / 1.1 x 106 Msun
  • Filling factor : ~ 30 / 1.5 / 0.5 x 10-4
  • Covering factor : ~ 0.5 / 0.5 / 0.5

Consider other components 

the various components
The Various Components

Thermal gas :

nth; Pth; Tth

Relativistic gas :

ffrel; Prel ~ B2/8π

Line Emitting gas :

ffem; nem; Pem; Vem

ISM

nism~ 1

Assume/show : Prel~ Pth~ Pem ~ Pism

slide43

Pressures : Prel, Pem, Pth, Prad

  • Log P/k~ 6.5 / 6.0 / 5.5 K cm-3
    • Quite high > radio galaxy lobes
    • All components deep within galaxy ISM
  • All pressures drop with radius (~ r -1)
    • As expected for galaxy ISM context
  • Approximate pressure balance between

different components : Prel~ Pem (~ Pth)

  • Relativistic & radiation pressure too low

to accelerate ionized gas (by ~x10)

    • Need dynamical (ram) pressure of jet
energy comparisons
Energy Comparisons

Relative energies in different parts :

  • UV (FIR) ~ 1000 (~1043 erg/s)
  • Emission lines ~ 1000
  • Kinetic ~ 1
  • Relativistic ~ 1
  • Expansion /lobe ~ 1
  • Radio ~ 0.2

Simple inferences 

slide45

Conclusions from energy comparisons

  • Photons dominate by x1000 ; Lem~ LUV

 supports photo- over shock ionization

 should not derive Ljet from Lem (see later)

2. Expansion / KE / Relativistic all similar

 flows can accelerate gas & power radio source

4 jet properties
4. Jet Properties

Estimating jet energy and momentum :

Use emission line & lobe properties :

  • Ej~ KEem+αe Elobe~ 2-5 Elobe

αe = synchrotron loss; adiabatic loss; ffrel

Lj = Ej/Tage~ 2-5 x 1040 erg/s

  • Gj~αm Gem~ 2-5 Gem

αm = covering factor loss ; drag loss

Fj = Gj/Tage~ 2-5 x 1033 dyne

slide47

JET LUMINOSITY

EKE ~ Σ½M V2

Lj

Elobe~ PV ~ αeErel

Lj~(EKE + αeErel )/tage

JET MOMENTUM

Gem ~ ΣM V

Fj

Fj~αmGem / tage

αm~ αdrag αlcf ~ 2 – 5

αe~ αsyn αad αff ~ 2 – 10

jet properties model
Jet Properties (model)
  • Components:
    • Relativistic & thermal; ratio defined by ffrel
    • Both move at Vj
  • Pressure balance : Prel~ Pth
    • We know Prel from radio physics ~ Bme/8π
  • Energy : Ej~ KEth + Wth + Wrel
    • Wrel = (4/3)Prel ; Wth = (5/2) Pth
  • Momentum : Gj~ Gth + Grel = Gth
    • Relativistic component has ~zero inertia

2

jet properties derived
Jet Properties (derived)

Use Lj Gj Pj Aj to derive many properties (>100pc)

  • Thermal material dominates jet energy and momentum
    • Relativistic gas has little/no momentum
    • KEj/Uj~ Fj/Aj/Pj~ 10 / 3 / 2  KE dominates energy
  • Jet velocity~ 1-few x Vgas
    • 2Lj/Fj~ Vj~ 300 – 3000 km s-1
  • Ram pressure dominates : Pram~ 30 / 7 / 4 x Prel
    • Can accelerate to Vem over Tage for Ncol~ 1021 cm-2
    • Only mild shocks : Pram~ρemVsh2  Vsh ~ 10-50 km s-1
    • Not acceleration by impulsive shocks; maybe wind/ablation
jet properties derived50
Jet Properties (derived)
  • Jet density (thermal) : 0.1 - 5 cm-3
    • Consistent with entrained ISM
  • Jet temperature : Tj~ Pj/njk ~ 106 K
    • ~0.1-0.7 Temperature from thermalized Vj
    • again consistent with entrained ISM
  • Jet Mach number : 5 / 2.5 / 2  transonic
    • Consistent with entrainment and decollimation
  • Jet mass flux: ~ Mem over region lifetime
    • Could be entrained ISM
    • Could become ‘thermal’ component of lobe
comparison with previous work
Comparison with previous work

Many partial interpretations

One thorough analysis :

 Bicknell, Dopita & Sutherland ’98

They use shocks to infer jet properties,

in particular : jet energy & momentum

This yields significantly different results

slide52

JET LUMINOSITY

EKE ~ Σ½M V2

Our analysis

Lj

Elobe~ PV ~ αErel

Lj~(EKE + αErel )/tage

Emission

Lines : Lem

Bicknell et al ‘98

Shock

Lj

Lj~Lem~100 x L5007

For Mkn 78 & other Seyferts : Lj (them) ~ 1000 xLj (us)

slide53

JET MOMENTUM

Our analysis

Gem ~ ΣM V

Fj

Gradual acceleration

Fj~αGem / tage

Bicknell et al ‘98

Vsh~Vem~ 500 km/s

Shock

nem~ 103cm-3

ρemVsh

Pram~ ρjVj2

2

Emission Line

Cloud

ρjVj2 ~ ρemVsh

2

Impulsive acceleration

For Mkn 78 & other Seyferts : Fj (them) ~ 100 xFj (us)

summary
Summary
  • Jet-gas interactions (JGI) are important
  • VLA & HST data on Seyfert with dominant JGI
  • Inspection reveals likely JGI scenario
    • 3 regions suggest temporal development
  • Ionization study rejects role of shocks
    • AGN photoionization of thick & thin components
  • Data provide information on jet properties :
    • relatively low power, low speed, transonic, dense jet
    • dominated by thermal gas, at Tj ~ 0.5 x T(Vj)
    • ram pressure ~ 2-10 x internal pressure
  • Overall context : thermal jet/wind driven ablata
slide56

New HST Project :

1 or 2 slits on six other objects with evidence for JGI.