1. XMM results in radio-galaxy physics Judith Croston CEA 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 284, z=0.25 3C 223 z=0.14 Lobe emission from two nearby FRIIs (Croston et al. 2004, MNRAS 353 879) IC scattering of CMB; B ~ B eq 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.

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) B eq, with peak at B ~ 0.7 B eq. Internal energy always within a factor of two of minimum value. Energetically dominant proton population unlikely.

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

9. Dynamics and particle content in FRIs XMM confirms Einstein/ROSAT results for FRIs: P ext >> P int(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 T env. Heated, entrained material (T ~ 3 – 5 keV) most plausible. Relativistic protons possible, but need p/e ~ 200.

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

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 L X /T X 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 L x and T x constraints, detailed study of gas distribution in radio-loud and quiet groups.