1 Jets from Active Galactic Nuclei: Observations and Models S. Massaglia S. Massaglia DFG: A. Ferrari, T. Matsakos, O. Tesileanu, P. Tzferakos INAF-OATo:

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Jets from Jets from Active Galactic Nuclei:Active Galactic Nuclei:

Observations and ModelsObservations and Models

S. MassagliaS. Massaglia

DFG: A. Ferrari, T. Matsakos, O. Tesileanu, DFG: A. Ferrari, T. Matsakos, O. Tesileanu, P. TzferakosP. TzferakosINAF-OATo: G. Bodo, A. Mignone, P. Rossi, INAF-OATo: G. Bodo, A. Mignone, P. Rossi, E. Trussoni E. Trussoni Enrico Fermi Institute, University of Chicago Enrico Fermi Institute, University of Chicago Department of Astronomy, University of AthensDepartment of Astronomy, University of AthensMarie Curie project JETSETMarie Curie project JETSET

Congresso DFG, Aprile 2008Congresso DFG, Aprile 2008

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OverviewOverview

Normal and Active GalaxiesNormal and Active Galaxies

Jets from Radio GalaxiesJets from Radio Galaxies

Modelling Jets by Numerical Modelling Jets by Numerical Simulations: Simulations:

comparison with observationscomparison with observations

ConclusionsConclusions

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Normal GalaxiesNormal Galaxies

Stars contribute to the radiation Stars contribute to the radiation emission, emission,

limited to the optical band and limited to the optical band and whereabouts.whereabouts.

Typically, Typically, 10101111 stars of a galaxy emit a stars of a galaxy emit a luminosity of about luminosity of about 10104444 ergs s ergs s-1 -1 ((10101111

LL))

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Active GalaxiesActive Galaxies

Few galaxies (Few galaxies ( percent) are percent) are “pathological”:“pathological”:

1.1. The main contribution to the The main contribution to the luminosity is not from stars but from luminosity is not from stars but from an Active Nucleusan Active Nucleus R 30 kpc L 2 kpc L 10-5 kpc

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Active GalaxiesActive Galaxies

2.2. The emission is not confined to the The emission is not confined to the optical band but extends to other optical band but extends to other frequencies.frequencies.

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MotivationsMotivations

Why studying Active Galaxies:Why studying Active Galaxies:

1.1. For investigating the formation and For investigating the formation and merging events during the life of merging events during the life of galaxies.galaxies.

2.2. To understand the formation of To understand the formation of

cluster of galaxies. cluster of galaxies. 3.3. Active Galactic Nuclei are a likely Active Galactic Nuclei are a likely

source of the most energetic cosmic source of the most energetic cosmic rays.rays.

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Radio Galaxies and JetsRadio Galaxies and Jets

3C 983C 31

The most prominent feature in some The most prominent feature in some active galaxies are collimated outflows of active galaxies are collimated outflows of matter in form of radio matter in form of radio jetsjets. . These galaxies are then called These galaxies are then called radio radio galaxiesgalaxies..

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Pictor A (z=0.035)Pictor A (z=0.035)Nucleus to hot-spot Nucleus to hot-spot 270 kpc 270 kpcjet jet 120 kpc 120 kpc

Radio GalaxiesRadio Galaxies

Radio emissionRadio emissionSynchrotron:Synchrotron:

F(F() ) --

0.50.5

Electron powerElectron powerlaw distributionlaw distribution

n(E) n(E) E E-p-p

p=p=22+1+1

Synchrotron Radio to X-raysSynchrotron Radio to X-rays

Radio: synchrotron Radio: synchrotron X-rays: X-rays: synchrotron+ICsynchrotron+IC

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Very Large ArrayVery Large Array

27 radio antennas in a Y-shaped configuration on the 27 radio antennas in a Y-shaped configuration on the Plains of San Agustin fifty miles west of Socorro Plains of San Agustin fifty miles west of Socorro (NM). Each antenna is 25 m in diameter. The data (NM). Each antenna is 25 m in diameter. The data from the antennas is combined electronically to give from the antennas is combined electronically to give the resolution of an antenna 36 km across, with the the resolution of an antenna 36 km across, with the sensitivity of a dish 130 m in diametersensitivity of a dish 130 m in diameter

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Origin of Radio Jets from Origin of Radio Jets from AGNs: AGNs:

The Black-Hole Paradigm The Black-Hole Paradigm

Jets originate around SMBH of 10Jets originate around SMBH of 1088-10-101010 M M

accreting mass through a magnetized accreting mass through a magnetized disk disk

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Are Active Galaxies peculiar objects or a Are Active Galaxies peculiar objects or a phase of their life common to most of phase of their life common to most of them? them?

At the centers of many normal galaxies At the centers of many normal galaxies the presence of a SMBH the presence of a SMBH has been detected has been detected by indirect means.by indirect means.

At the center of At the center of the Milky Way there the Milky Way there is a BH of one millionis a BH of one millionsolar massessolar masses

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Radio luminosity: Radio luminosity: 10104141-10-104444 ergs ergs ss-1-1

Size: Size: a few kpc – some Mpca few kpc – some Mpc

Life timescale: Life timescale: 101077-10-1088 ys ys

Magnetic fields: Magnetic fields: 10 – 1010 – 1033 GG

Kinetic power: Kinetic power: 10104444-10-104747 ergs s ergs s-1-1

Radio Galaxies: Main factsRadio Galaxies: Main facts

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Modelling Radio JetsModelling Radio JetsHypothesis: Physics described by Hypothesis: Physics described by the Ideal Magneto-Hydrodynamic the Ideal Magneto-Hydrodynamic EquationsEquations

00

2

2 BBB

pdt

vd

Bvt

B

0

vt

0dt

dp

dt

dp

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Modelling Radio JetsModelling Radio JetsRelativistic estension of the MHD Relativistic estension of the MHD equations:equations:

vBvBBvb

bhwbpp

bbvwpbbvvwvf

pbbwbbvwU

Bvt

B

t

f

t

U

tt

Tiit

ijt

jijit

i

Ttt

ijt

i

i

,/,

,2

1

,,

,,

0

22

022

00202

3

1

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Modelling Radio JetsModelling Radio JetsMHD equations can be solved by MHD equations can be solved by numerical means only:numerical means only:

Define the integration domain and the system of coordinates

Set the initial and boundary conditions

Set parameters, carry out numerical integration

Analyze the results and compare to observations

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Basic physical parametersBasic physical parameters

Theoretical modeling andTheoretical modeling and numerical simulationsnumerical simulations of of jets on jets on large scale requirelarge scale require a minimum set a minimum set of of parameters:parameters:1.1. LorentzLorentz factor factor ( (Γ)Γ)

2.2. Jet Mach numberJet Mach number (M) (M)

3.3. Jet-Jet-ambientambient density ratio ( density ratio (η)η)

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Lorentz factor: jet one-Lorentz factor: jet one-sidednesssidedness

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Jet Mach number: indication Jet Mach number: indication of shocksof shocks

BBeqeq=4.6=4.61010-4 -4 GG

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Jet Mach number: indication Jet Mach number: indication of shocksof shocks

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Model of Jet TerminationModel of Jet Termination

jetjet

TerminTerminalalshockshock

21Cygnus A Cygnus A (FR II) (FR II) - VLA, 6cm- VLA, 6cm

22Cygnus A Cygnus A (FR II) (FR II) - VLA, 6cm- VLA, 6cmbow shock

undisturbed intergalactic gas

“cocoon” (shocked jet gas)

splash point

backflow

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Numerical simulation Numerical simulation

Supersonic andSupersonic andUnderdense jetUnderdense jet

We use the (M)HDWe use the (M)HDcode PLUTO, basedcode PLUTO, basedon high resolution on high resolution shock-capturingshock-capturing schemes.schemes.((http://plutocode.to.astro.itMignone et al. 2007)Mignone et al. 2007)

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Numerical simulationNumerical simulation

backflow

intergalactic gas

Mach disk

bow-shockContact discontinuity

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Numerical simulationsNumerical simulations

cocoon

intergalactic gas

splash point

bow-shock

backflow

Comparison of observed and simulatedComparison of observed and simulatedmorphologiesmorphologies

1.1. Relativistic (one-Relativistic (one-sidesideddnessness)), , ΓΓ>1>1 2.2. Supersonic (presence hot-spots)Supersonic (presence hot-spots), ,

MM>1>1 3.3. UnderdenseUnderdense (presence of cocoons) (presence of cocoons), ,

ηη<1<1 (simulations)(simulations)

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Chandra X-ray Observatory

CXC

Cygnus A Wilson et al. (2001)Wilson et al. (2001)

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ConclusionsConclusions

The study of the Active Galaxies The study of the Active Galaxies

has a crucial role in astrophysics has a crucial role in astrophysics

and cosmic ray physics. and cosmic ray physics. It provides a test ground for new It provides a test ground for new

domains of the physics.domains of the physics. Numerical simulations important Numerical simulations important

forfor

the comparison with observations.the comparison with observations.

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Jet instability and brakingJet instability and braking

Jet instabilities: linear growth τKH ~ 2π MJ

RJ / cs

Nonlinear growth: τKH 10 RJ / cs

Mixing and mass entrainment

Jet braking

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Jet instability and brakingJet instability and braking

10,3,10 4

s

j

amb

jet

c

vM

Rossi et al. 2008)Rossi et al. 2008)