X-ray constraints on cluster-scale emission around high-redshift radio galaxies Elena Belsole

1. X-ray constraints on cluster-scale emission around high-redshift radio galaxies Elena Belsole in collaboration with D. Worrall & M. Hardcastle Distant clusters of Galaxies Ringberg Workshop

2. Outline • Introduction • Theory for jet confinement • Environment expected from radio observations and minimum energy condition • What was the situation with ROSAT • Observational situation: • An example: Two sources observed with XMM • The new picture from Chandra and XMM • Conclusions • Future prospects Distant clusters of Galaxies Ringberg Workshop

3. Introduction • Powerful (P178 Mhz > 1027 W Hz-1 sr-1) radio sources are visible at high redshift • Sources classified as FRII have a double sided jet which terminates in hotspots sometimes at distances of ~ 1Mpc • Jet propagation and termination require a gaseous environment for confinement (standard beam-model, Begelman et al. 84) • X-ray emission traces the hot gas component. • Powerful radio galaxies are possible tracers of galaxy groups and clusters Distant clusters of Galaxies Ringberg Workshop

4. Introduction • Advantages: • Radio selection: not biased towards luminous clusters (unlike X-ray flux limited samples) • Radio observations can be used alone to estimate the external gas density, if minimum energy condition applies, : ρ∝ (B/vL)2 – ram pressure confinement eq. • Easier than SZ for these sources • Disadvantages • In X-ray: component separation and sensitivity (low SB objects) • Not many active radio sources; are we looking at a particular class of object? Distant clusters of Galaxies Ringberg Workshop

5. Observational framework Most powerful radio sources are at high redshift By analogy to low-z sources (Cygnus A) minimum energy condition is assumed (e.g. Wellman et al. 97) These studies predict clusters with ICM densities comparable to low-z clusters and similar shape. ROSAT observations: Evidence difficult to obtain for external environment around RGs and QSO at z>0.5 [Worrall et al. 94, Crawford & Fabian 96, Hardcastle & Worrall 99, Crawford et al. 99] Question is still open Distant clusters of Galaxies Ringberg Workshop

6. Observational status: the new generation X-ray satellites Distant clusters of Galaxies Ringberg Workshop

7. 3C292 z=0.71 XMM exposure time: 20 ks Belsole et al. 2004 Distant clusters of Galaxies Ringberg Workshop

8. 3C292 Lobes Unabsorbed power law =1.9±0.3 Flux (1 keV) = 4 nJy Total IC flux 2.4 nJy Environment β=0.8 , rc – 19.7 arcsec kT = 2.2 +3.12-0.85 keV LX (bol)= 6.5 1043 erg/s Distant clusters of Galaxies Ringberg Workshop

9. 3C184 z:0.994 XMM/EPIC image 54 ks (MOS) 16 ks (pn) Belsole et al. 2004 Distant clusters of Galaxies Ringberg Workshop

10. X-ray spectrum: 3 components S = 1.5±1.0 from Chandra NH =4.9 1023 cm-2; H = 1.4±0.35 kT = 3.6+ 14.1-1.8 keV; LX = 8.3±1.8 x 1043 erg/s 3C184 Point source +  model  = 0.66, rc = 200 kpc evidence of extended emission LX ~ 5.9 x 1043 Distant clusters of Galaxies Ringberg Workshop

11. 3C184 HST (Deltorn et al. 97) Excess of galaxies + 11 galaxies at z~1 Arc detection and mass within arc ~2 x 1013 Msun Chandra images and 5 GHz radio contours the pressure of the external medium is a factor of 20 lower than the minimum internal pressure of the galaxy ==> the galaxy is expanding Distant clusters of Galaxies Ringberg Workshop

12. Observational status: • summary of current results • FRII in the 3CRR and with 0.5<z<1.0 [Donahue et al. 03; Crawford & Fabian 03; Hardcastle et al 02; Brunetti et al. 02] • Only 3 objects have measured X-ray temperature: • 3C220.1 T~ 5.6 keV (Worrall et al. 2003) • 3C184 T~3.5 keV (Belsole et al. 2004) • 3C292 T~2.2 keV (Belsole et al. 2004) • Luminosities are easier to estimate Distant clusters of Galaxies Ringberg Workshop

13. N Bolometric LX (1043 erg/s) Distant clusters of Galaxies Ringberg Workshop

14. Observational status: • summary of current results • FRII in the 3CRR and with z>0.5 [Donahue et al. 03; Crawford & Fabian 03; Hardcastle et al 02; Brunetti et al. 02] • Only 3 objects have measured X-ray temperature: • 3C220.1 T~ 5.6 keV (Worrall et al. 2003) • 3C184 T~3.5 keV (Belsole et al. 2004) • 3C292 T~2.2 keV (Belsole et al. 2004) • Luminosities are easier to estimate … • and largely found to be ~ 3-4 1043 erg/s kT ~ 1.5-3.5 keV Extended emission associated with lobes (IC) and hotspots (IC - SSC - Syn) Distant clusters of Galaxies Ringberg Workshop

15. Conclusions • Detection of diffuse emission from most of the radio sources at z>0.5 • Most of the extended emission is radio related • X-ray environment mostly of poor clusters (with few exceptions) but sufficient to confine the lobes • FRII radio galaxies are tracers of a broad range of environments ? • IF yes they provide an unbiased sample of the structures in the Universe • caveat • It is difficult to separate components! Distant clusters of Galaxies Ringberg Workshop

16. Future prospects • Quantitative investigation of the X-ray environment .... In progress (see Belsole et al. 2005, MNRAS, sub; Belsole et al. 2006, in prep.) • Comparison with lobe internal pressure (see also Croston et al. 2005) ; is the minimum energy condition satisfied? • Comparison with lower redshift sources: evolution? Distant clusters of Galaxies Ringberg Workshop