Jet Interactions with the Hot Atmospheres of Clusters & Galaxies

Jet Interactions with the Hot Atmospheres of Clusters & Galaxies

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B.R. McNamara

University of Waterloo

Girdwood, Alaska May 23, 2007

L. Birzan, P.E.J. Nulsen, D. Rafferty, C. Carilli, M.W. Wise

Harvard-Smithsonian Center for Astrophysics

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optical, radio, X-ray

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Perseus MS0735.6+7421

E ~1059 erg E ~ 1062 erg

1’ = 200 kpc

1’= 20 kpc

Fabian et al. 05 McNamara et al. 05

M=1.3 shock

weak shock

ghost cavity

Cavity Energetics & Kinematics

r

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ts = r /cs

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E =γpV

γ −1≈1055 −1062erg

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tbuoy = r /v t ∝ r / 2gV

Cavity Demographics

McNamara & Nulsen 07, ARAA

nuclear distancecavity radius

crossings age

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N ∝ R−1

Broader Consequences

• Jets may quench cooling flows in clusters, groups, galaxies

• Controlled by feedback: cold/Bondi accretion

• Puzzle: how jets heat the gas

• Galaxy and SMBH formation: luminosity function, “cosmic downsizing”

• Cluster “preheating” ~1/4 keV per particle

• Magnetic fields, halos/relics, CR acceleration, etc.

• New theoretical heating & jet models

• Understanding radio jets themselves

McNamara & Nulsen 07, ARAA

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Hmm…Kerosene. Must be a heavy jet.

Can we use X-ray cavities to understand radio sources?

Using X-ray Halos as Jet Calorimeters

Energy = magnetic fields + particles

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X-ray Radio

Constrain: ages/dynamics, magnetic field & particle content, equipartition

• Laura Birzan’s thesis: 24 systems, VLA data at 0.327, 1.4, 4.5, 8.5 GHz, Chandra imaging

• low specific accretion rates << Eddington (Rafferty 06)• Largely clusters & groups

Enormous range in radiative efficiency

<Pcav/Lrad> = 2800

Lobes only

{Pcav/Lrad}med = 120

tHubble

tradio = Ecav/Lrad = radio cooling timescale

Birzan 07

radio ages

tcool,x

Cyg A

Rafferty 06

Birzan 04

HCG 62

Synchrotron age versus dynamical age

Birzan 2007, PhD

1:1

tcav > tsyn

Projection?R0 ?V0 ?

9/18

Lobes out of equipartition

equipartition

pressure balance Birzan 2007, PhD

k = 1

Dunn & Fabian 04

Jet Composition

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E = pV

. . .

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ε j = E v j tπrj2

gas pressure

De Young 2006

P=nkT

Energy density in jet

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v j = 0.1c

rj = 0.1kpc

t = tsyn, tbuoy

energy density e-

gas pressure>> 1Decollimaton

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E.

Lrad<1 for vj > 0.5c

Cold protons, Poynting flux magnetic collimation?

(won’t see jet)

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E = EB + Ep ∝B2

8πΦV + (1+ k)B

−3

2L rad

X-ray/Radio Constraints on Lobe Content

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Φ ≈1

variables: magnetic field, B, ratio of protons to electrons, k

X-ray Radio

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tsyn ∝B1/ 2

B2 + Bm2ν c (1+ z)[ ]

−1/ 2

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Beq ∝ Lrad2 7V −2 7 (1+ k) /Φ[ ]

2 7

Additional constraints: tsyn = tbuoy,

equipartition Beq (k) pressure balance Bp (k)

from detectability considerations

Particle & Magnetic Field content: large k

see also, Dunn, Fabian, Taylor 2005 Dunn & Fabian 2004

Birzan 2007

Gray: determine Bbuoy(tsyn=tbuoy), solve for k

Hatched: equipartition between k & B

k >> 1, large spread

Equipartition between B, k implies

assume pressure balance

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B ≥ 50μG

Additional Issues

Thermal pressure support for cavities?

T gas > 20 keV

Blanton et al. 02, Nulsen et al. 02, Gitti et al. 07

Jet/lobe dynamics: how reliable is tcav ?

• reasonable agreement with simulations (eg. Jones & De Young 05)

• factors of several errors likely, but not factors of 10, based on shock constraints

consider Hydra A, for example…

Hydra A: Complex Dynamics Z=0.053

Wise et al. 07

Shock

M = 1.34

E = 9x1060 erg s-1

t = 140 Myr

Radio: Lane et al. 04/Taylor

Low Radio Frequency Traces Energy

74 MHzWise et al. 07

shock

6 arcmin

380 kpc

Hydra A

Wise et al. 07

1061 erg

Nulsen et al. 05

tshock= 140 Myr

tbuoy= 220 Myr

tbuoy > tshock

MHD jets?

Summary

• Cluster radio sources radiatively inefficient• No simple relationship between radio power & jet power• Jet power much higher than early estimates• Synchrotron ages decoupled from dynamical ages• Equipartition invalid in lobes• Ratio of heavy particles (protons) to electrons, k >> 1• Evidence for complex lobe/cavity dynamics (eg. Hydra A)• Poynting jets? See poster by Diehl, Li, Rafferty, et al.

shock

6 arcmin

380 kpc

Hydra A

McNamara 95

McNamara et al. 00

U-band

Wise 05

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