Extragalactic Jets – Girdwood, Alaska 23/05/07 Jet/environment interactions in FRI radio galaxies...
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Transcript of Extragalactic Jets – Girdwood, Alaska 23/05/07 Jet/environment interactions in FRI radio galaxies...
Extragalactic Jets – Girdwood, Alaska
23/05/07
Jet/environment interactions in FRI
radio galaxiesJudith CrostonUniversity of Hertfordshire
With thanks to: Martin Hardcastle, Mark Birkinshaw, Diana Worrall,
Ralph Kraft, Dan Evans, Robert Laing
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?
NGC 1044
3C 296 NGC 315
3C 76.1 3C 66B
3C 31
NGC 6251
3C 449
NGC 4261
A representative sample of FRI environments with XMM-Newton
What is the relationship between large-scale
environment and radio-source properties?
Cavities
Asymmetries
Surface brightness profiles for NGC315?Croston et al. 2003, MNRAS, 346, 1041
What are FRIs made of?
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 don’t?
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
Jets within lobes
No surroundinglobes
NGC1044 – no lobesThe first direct evidence that entrainment is responsible for the apparent pressure imbalance?
3C296 – lobes
Lobe sourcesNo lobe sources
What is their impact on the environment?
RLRQXMM RGs
(groups sample from Croston et al. 2005, MNRAS, 357, 279)
Can PdV work by current radio source explain this
effect?
Kraft et al. 2003, 2006 + see Hardcastle poster
Croston et al. 2007, ApJ, 660, 191
Cen A NGC 3801
NGC 1052
Summary• FRIs of all morphological types live in group
environments (1041 erg s-1 < LX < 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.
Thanks
Pressure ratio vs. distance where jet becomes 2-sided