Jetenvironment interactions in FRI radio galaxies

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Jet/environment interactions in FRI radio galaxies
Judith CrostonUniversity of HertfordshireWith
thanks to Martin Hardcastle, Mark Birkinshaw,
Diana Worrall, Ralph Kraft, Dan Evans, Robert
Laing
Extragalactic Jets Girdwood, Alaska 23/05/07
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Questions

• What is the relationship between large-scale
  environment and radio-source properties?
• What are FRIs made of?
• What is their impact on their environment?

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A representative sample of FRI environments with
XMM-Newton
NGC 1044
3C 296
NGC 315
3C 31
3C 76.1
3C 66B
NGC 4261
NGC 6251
3C 449
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What is the relationship between large-scale
environment and radio-source properties?
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Cavities
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Asymmetries
Surface brightness profiles for NGC315?
Croston et al. 2003, MNRAS, 346, 1041
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What are FRIs made of?
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Internal vs. external pressures

• FRI equipartition lobe pressures are typically
  lower than thermal pressure of environment (e.g.
  Morganti et al. 1988, Worrall Birkinshaw 2000,
  Croston et al. 2003).
• Lack of IC emission rules out dominant electron
  population as source of missing pressure.
• Average pressure ratios for this sample range
  from 0.7 and 45.
• Not all FRIs require pressure from non-radiating
  particles
• Is there anything special about the ones that
  dont?

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Pressure ratios and particle content

• If entrainment is the origin of the non-radiating
  pressure component, then the apparent imbalance
  should depend on its efficiency.
• Sources with jets inside lobes 3C 76.1, 3C 296,
  NGC 4261, 3C 66B(?)
• Sources with jets propagating through the IGM
  3C31, NGC1044, NGC315, 3C449, NGC6251

No surrounding lobes
Jets within lobes
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The first direct evidence that entrainment is
responsible for the apparent pressure imbalance?
NGC1044 no lobes
Lobe sources No lobe sources
3C296 lobes
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What is their impact on the environment?
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RL RQ XMM RGs
(groups sample from Croston et al. 2005, MNRAS,
357, 279)
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Can PdV work by current radio source explain this
effect?
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Cen A
NGC 3801
Croston et al. 2007, ApJ, 660, 191
Kraft et al. 2003, 2006 see Hardcastle poster
NGC 1052
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Summary

• FRIs of all morphological types live in group
  environments (1041 erg s-1 lt LX lt 1043 erg s-1)
• Radio source morphology is related to gas
  distribution.
• Non-radiating particles are required in most, but
  not all, FRIs to achieve pressure balance with
  the environment.
• Pressure imbalance is linked to source
  morphology direct evidence that entrainment
  provides the non-radiating particle population.
• Radio-source environments are hotter than
  comparable radio-quiet groups, but PdV work by
  the current radio galaxy may not be able to
  achieve this heating.
• Small (young?) FRIs can shock-heat galaxy
  atmospheres, injecting large amounts of energy
  potentially an important galaxy feedback process.

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Thanks
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Pressure ratio vs. distance where jet becomes
2-sided