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3D Magnetohydrodynamics Simulations of Cluster Radio Sources Martin Krause Ludwig-Maximilians-Universitt Mnchen Max-Planck-Institut fr extraterrestrische Physik Excellence Cluster Universe with: Paul Alexander, Hans Bhringer, Gayoung

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SLIDE 1

3D Magnetohydrodynamics Simulations of

Cluster Radio Sources

Martin Krause

Ludwig-Maximilians-Universität München Max-Planck-Institut für extraterrestrische Physik Excellence Cluster Universe with: Paul Alexander, Hans Böhringer, Gayoung Chon, Martin Hardcastle, Daniel Hopton, Julia Riley, Joachim Trümper

Wednesday, June 17, 2015

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SLIDE 2

A radio source

core 2 jets 2 lobes >2 hot spots

Cygnus A, courtesy: Chris Carilli

Fanaroff Riley (1974) class II

Wednesday, June 17, 2015

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SLIDE 3

Fanaroff Riley class I

M84, 5 GHz, Laing+ 2011

gradient

flaring point

4 kpc 1 kpc 0.2 kpc

Wednesday, June 17, 2015

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SLIDE 4

Cluster radio sources

A2255 Govoni et

  • al. 2006

3C449, 2231.2+3732 Guidetti et al. 2010

group of galaxies 2231.2+3732 z=0.017085

Some FR II - mostly FR I

Wednesday, June 17, 2015

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SLIDE 5

X-ray cavities & shocks

MS 0735+7421 Perseus

Cygnus A

Chon, Böhringer, Krause & Trümper 2012 Birzan+2008

Active radio sources: strong impact on ICM M87

Million+2010

Wednesday, June 17, 2015

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SLIDE 6

Best+2007

  • BCG: ~30%
  • Core: ~10-20 %
  • Outskirts: <≈

10 %

  • Optical AGN

independent of radio AGN (Shabala+ 2008)

FR II limit Duty cycle

}~ few

times

Central cluster galaxies: more radio loud

Consistent with feedback loop idea: radio AGN (only) couples to ICM

Wednesday, June 17, 2015

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SLIDE 7

Cavity power

Birzan+2008

4 PV cavity power vs. radio power

  • Volume (X-ray

cavity) x ext. pressure = energy

  • neglects shocks
  • active sources:

x 10-100, detailed models: Kaiser & Alexander 1999, Zanni+2003, Krause 2005

Cygnus A

Wednesday, June 17, 2015

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SLIDE 8

Heating / cooling balance?

Best+2007 Birzan+2008

4 PV cavity power

  • vs. radio power

Radio sources + conduction No!(?) But large modelling uncertainties.

Wednesday, June 17, 2015

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SLIDE 9

Heating / cooling balance?

Best+2007 L1.4 / W Hz-1 Jet power / W Self-similar / analytic modelling

Turner & Shabala 2015 Turner & Shabala 2015

Change radio source model: yes! (with conduction in massive clusters)

Wednesday, June 17, 2015

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SLIDE 10

Questions

  • Observations ⇔ jet energy flux ?
  • Jet energy flux ⇔ ICM heating (radius) ?
  • Jet morphological type ⇔ AGN type ?

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SLIDE 11

Jet modelling

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SLIDE 12

Jet-environment interaction

  • Scheuer 1974: cocoon & cavity formation / jet

collimation by cocoon

  • Falle 1991, Kaiser & Alexander 1997, Komissarov &

Falle 1998: identified critical scale L1, after which self-similarity, crucial factor: self-collimation by cocoon pressure

  • Simulations: self-similar evol. confirmed when inc.

self-col. by cocoon pressure (Komissarov & Falle 1998)

  • Deviations from self-similarity at outer scale L2

(Alexander 2002, Hardcastle & Krause 2013)

Wednesday, June 17, 2015

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SLIDE 13

Jet-environment interaction

  • Outflows with
  • pening angle < π

+L1: wind mass = swept up mass

  • L1a:

sideways pressure = ambient pressure ⇒ recollimation

  • L1b:

jet density = ambient density ⇒ cocoon formation

  • L1c:

forward ram pressure = amb. pressure ⇒ hot spot limit unless collimated

recollimation shock

Wednesday, June 17, 2015

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SLIDE 14

Jet-environment interaction

  • Outflows with
  • pening angle < π

+L1: wind mass = swept up mass

  • L1a:

sideways pressure = ambient pressure ⇒ recollimation

  • L1b:

jet density = ambient density ⇒ cocoon / lobe formation

  • L1c:

forward ram pressure = amb. pressure ⇒ hot spot limit unless collimated

Wednesday, June 17, 2015

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SLIDE 15

Jet-environment interaction

  • Outflows with
  • pening angle < π

+L1: wind mass = swept up mass

  • L1a:

sideways pressure = ambient pressure ⇒ recollimation L1b: jet density = ambient density ⇒ cocoon formation L1c: forward ram pressure = amb. pressure ⇒ hot spot limit unless collimated

Wednesday, June 17, 2015

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SLIDE 16

Collimation (or not) by ambient pressure

  • Initially conical beam, density & ram pressure∝r-2
  • 3 parameters: solid angle Ω(θ), external Mach

number Mx, scale L1

sideways ram press. = amb press. jet density = amb. density

  • forw. ram press. = amb. pressure

[Krause+ 2012]

limit

Wednesday, June 17, 2015

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SLIDE 17

Simulations

  • Standard hydrodynamics:
  • mass conservation
  • momentum conservation
  • energy conservation
  • 2.5D (axisymmetric) + AMR
  • FLASH-code

Wednesday, June 17, 2015

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SLIDE 18

FR II recipe

  • 1st: form cocoon (L1b)
  • 2nd: collimate (L1a)
  • 3rd: have terminal shock (L1c)
  • i.e. arrange: L1b < L1a < L1c
  • ...
  • Density ratio set by

current external Mach number:

[FLASH code, 2.5D-HD, AMR]

Wednesday, June 17, 2015

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SLIDE 19

FR I recipe

  • 1st: form cocoon (L1b)
  • 2nd: have terminal shock
  • 3rd: (try to) re-collimate
  • i.e. L1b < L1c < L1a

Wednesday, June 17, 2015

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SLIDE 20

FR I recipe

  • 1st: form cocoon (L1b)
  • 2nd: have terminal shock
  • 3rd: re-collimate

Wednesday, June 17, 2015

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SLIDE 21

Range of morphologies

θ=5deg θ=15deg θ=30deg M_ext=5 M_ext=500

Krause+2012

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SLIDE 22

Quantifying emission:

  • assume emission prop to div(v) (particle

acceleration at shocks):

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SLIDE 23

FR classification

(transform 3D, project surface brightness)

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SLIDE 24

Questions

  • Jet morphological type ⇔ AGN type ?

Correlated: FR I: wide opening angle, ADAF, hot-mode accretion, low jet power, FR II when small large-scale FR II: narrow opening angle, opt. AGN, cold-mode accretion, SF galaxies

Wednesday, June 17, 2015

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SLIDE 25

2 types of simulations

  • conical jets: L1→ L2,

expensive, only < Mx=40

  • collimated jets, 3D MHD (background)

2 keV cluster

Wednesday, June 17, 2015

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SLIDE 26

Conical jets: L1→ L2, Mx=40

  • above: L > L2, as

typically observed

  • beta-profile, beta =

0.35, 0.55, 0.75, 0.90

strong shock weak shock, pressure equilibrium no sideways lobe expansion

[log(density)]

jets collimated by ambient pressure weak shocks / lobe vortices buoyancy inflowing ICM

Wednesday, June 17, 2015

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SLIDE 27
  • Lobe volume grows

slower than self- similar

  • Radio emission
  • verpredicted by

self-similar models

  • true jet power >

jet power (self-sim) self-similar

Lobe volume

Wednesday, June 17, 2015

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SLIDE 28

Cavity power estimates

Same power, different environment

  • Shocked region energy ≈ lobe energy ≈ total / 2

Lenght / kpc Shocked region energy / pext Vlobe Total source energy ≈ (4-20) x pext Vlobe 300 10 100 1

Wednesday, June 17, 2015

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SLIDE 29

Entropy profile

  • Core entropy greatly increased by radio

source, but only for L < L2

  • Buoyancy: low entropy gas comes back in
  • Overall effect: 10-20% core entropy increase

Wednesday, June 17, 2015

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SLIDE 30
  • Magnetic

fields

  • 3D crucial
  • init:

jet: toroidal ambient: turbulence, scaled with density

Wednesday, June 17, 2015

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SLIDE 31

Magnetic topology: lobe magnetic energy fractions

  • Convergence: 1/3 toroidal, 2/3 longitudinal

Wednesday, June 17, 2015

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SLIDE 32

Luminosity-length diagram

  • same jet power/ ≈ factor 6 difference due to

each, environment & jet field strength

Wednesday, June 17, 2015

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SLIDE 33

Double jets - binary black holes?

Cygnus A X-ray Chon+ 2012 main cavity(ies) extra cavity

Wednesday, June 17, 2015

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SLIDE 34

Oldest electrons in this side cavity

Chandra X-ray + VLA 327 MHz

Wednesday, June 17, 2015

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SLIDE 35

3D - 2 jets: 1045 erg/s ⊥ 2x1047 erg/s

Wednesday, June 17, 2015

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SLIDE 36

Comparison to 3D simulation: 2 perpendicular jets

4 X-ray enhancements side cavities

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SLIDE 37

Similar in other sources

Cygnus A M87 / Virgo

MS 0735+7421

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SLIDE 38
  • Observations ⇔ jet energy flux ?

Ejet = 4-20 pV, Lradio (size) ≈ factor 10 scatter / env+mf, self-similar radio source models underestimate jet power

  • Jet morphological type ⇔ AGN type ?

Hot mode acc. ⇒ wide low pow. jets ⇒ FR I (large-sc.) Cold mode acc. ⇒ narrow high pow. jets ⇒ FR II

  • Jet energy flux ⇔ ICM heating (radius) ?

Efficient heating for L1 < size < L2 ≈ 10s of kpc, only

⇒ need frequent re-triggering (as observed).

Conclusions I

Wednesday, June 17, 2015

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SLIDE 39
  • Magnetic fields in FR II radio lobes turn longitudinal

(reproduce polarisarion data)

  • Binary black holes might produce radio sources in

different directions

Conclusions II

  • Discovery of an X-ray cavity near the radio lobes of Cygnus A indicating previous AGN activity

Gayoung Chon, Hans Böhringer, Martin Krause, Joachim Trümper, A&A, 545, L3 (2012)

  • A new connection between the opening angle and the large-scale morphology of extragalactic radio

sources

  • M. Krause, P

. Alexander, J. Riley, D. Hopton MNRAS, 427, 3196 (2012)

  • Numerical modelling of the lobes of radio galaxies in cluster environments
  • M. J. Hardcastle and M. G. H. Krause, MNRAS, 430, 174 (2013)
  • Numerical modelling of the lobes of radio galaxies in cluster environments II: Magnetic field

configuration and observability

  • M. J. Hardcastle & M. G. H. Krause, MNRAS, 443, 1482 (2014)

References

Wednesday, June 17, 2015