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