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XMM results in radio-galaxy physics

XMM results in radio-galaxy physics. Judith Croston CEA Saclay, Service d’Astrophysique. EPIC consortium meeting, Ringberg, 12/04/05. In collaboration with:. Martin Hardcastle (Hertfordshire) Mark Birkinshaw, Diana Worrall, Elena Belsole, Dan Evans (Bristol) Dan Harris (CfA).

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XMM results in radio-galaxy physics

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  1. XMM results in radio-galaxy physics Judith CrostonCEA Saclay, Service d’Astrophysique EPIC consortium meeting, Ringberg, 12/04/05

  2. In collaboration with: • Martin Hardcastle (Hertfordshire) • Mark Birkinshaw, Diana Worrall, Elena Belsole, Dan Evans (Bristol) • Dan Harris (CfA)

  3. Radio-galaxy morphologies

  4. Outstanding problems • Magnetic field strengths: can’t be directly measured from radio synchrotron emission, so equipartition ( min. total energy) commonly assumed • Particle content: electron-positron or electron-proton? • Dynamics: • FRIs: missing pressure? • FRIIs: supersonic or not? Solving these problems is essential to understanding radio-galaxy impact in groups and clusters.

  5. Radio galaxies in X-rays • Jets and hotspots (typically need Chandra resolution) • Radio lobes: • Non-thermal emission via inverse Compton scattering • Seed photons from CMBR, AGN nucleus and SSC • Measure internal energy density, magnetic field strengths • Infer particle content • Environments: • Radio galaxies are found in groups and clusters • Measure external density and pressure • Comparison with internal radio-lobe properties to study jet and lobe dynamics. • Temperature structure => heating

  6. XMM observations of IC emission from FRII lobes 3C 223 z=0.14 • Lobe emission from two nearby FRIIs (Croston et al. 2004, MNRAS 353 879) • IC scattering of CMB; B ~ Beq • Belsole et al. (2004) found similar results for three high-z FRIIs observed with XMM. • Grandi et al. (2003) detected lobe emission from Pic A – origin may be thermal or IC. 3C 284, z=0.25

  7. Chandra and XMM study(Croston et al. 2005, ApJ in press, astro-ph/0503203) • Sample of 33 radio galaxies observed by Chandra and XMM. • Lobe emission from 75% of sources. • Magnetic fields between (0.3 – 1.3) Beq, with peak at B ~ 0.7 Beq. • Internal energy always within a factor of two of minimum value. • Energetically dominant proton population unlikely.

  8. XMM observations of environments 3C 66B • FRI environments show: • SB deficits at radio lobes • Dense environments = large, rounded lobes • Less dense = narrow plumes • Heating (see later) 3C 449 Croston et al. 2003 MNRAS 346 1041; 2005 MNRAS 357 279, and Evans et al. 2005 MNRAS, in press, astro-ph/0502183)

  9. Dynamics and particle content in FRIs • XMM confirms Einstein/ROSAT results for FRIs: Pext >> Pint(equipartition) • extra particle content/departure from equipartition. • IC upper limit rules out electron domination to provide additional pressure. • Thermal upper limit rules out entrained gas with Tenv . • Heated, entrained material (T ~ 3 – 5 keV) most plausible. • Relativistic protons possible, but need p/e ~ 200.

  10. FRII environments • Also detected with XMM: • Groups rather than clusters • No evidence for shock-heating • Pext ~ Pint (measured from IC) => Not supersonically expanding?

  11. XMM detects shock heating • XMM and Chandra observations show radio-lobe shock heating of the X-ray environment from the small-scale lobes of Cen A (Kraft et al. 2003). (pictures from Kraft et al. 2003)

  12. AGN in cooling flows • M87 has thermal sub-structure associated with radio lobes (e.g. Belsole et al. 2001). • Is temperature structure consistent with models for counteracting cooling flows(e.g. Molendi 2002, Kaiser 2003, Ghizzardi et al. 2004)? => AGN energy input (rising bubbles/mixing) can balance cooling and produces multi-phase medium.

  13. Extended heating in FRI atmospheres • XMM-observed RG environments significantly hotter than LX/TX prediction. • ROSAT study: • RL groups hotter than RQ groups of the same luminosity. • 50% of E-dominated groups (= X-ray bright) are RL. (Croston et al. 2005, MNRAS, 357 279)

  14. Ongoing projects with XMM • Inner jet dynamics • Testing jet models (Laing & Bridle 2002) by measuring environmental properties. • Investigating role of environment in producing stable jets. • FRI environments • Completing sample that includes all common morphologies to understand jet/environment interactions in whole population. • Archive study of heating • Large fraction of ROSAT sample now observed by XMM. • Follow up heating study with better Lx and Tx constraints, detailed study of gas distribution in radio-loud and quiet groups.

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