Star Formation in High Redshift Submillimeter Galaxies and QSO Hosts
X-ray constraints on cluster-scale emission around high-redshift radio galaxies Elena Belsole
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Transcript of X-ray constraints on cluster-scale emission around high-redshift radio galaxies Elena Belsole
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
X-ray constraints on cluster-scale emission around high-redshift radio galaxies
Elena Belsole
in collaboration withD. Worrall & M. Hardcastle
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
Outline•Introduction
Theory for jet confinementEnvironment expected from radio observations and minimum energy conditionWhat was the situation with ROSAT
•Observational situation: An example: Two sources observed with XMMThe new picture from Chandra and XMM
•Conclusions•Future prospects
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
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
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
IntroductionAdvantages:
• 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 sourcesDisadvantages• In X-ray: component separation and sensitivity (low SB objects)• Not many active radio sources; are we looking at a particular class of object?
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
Observational frameworkMost powerful radio sources are at high redshiftBy 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
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
Observational status: the new generation X-ray satellites
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
3C292 z=0.71 XMM exposure time: 20 ks
Belsole et al. 2004
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
Lobes Unabsorbed power law =1.9±0.3Flux (1 keV) = 4 nJyTotal IC flux 2.4 nJy
Environmentβ=0.8 , rc – 19.7 arcseckT = 2.2 +3.12 -0.85 keVLX (bol)= 6.5 1043 erg/s
3C292
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
3C184 z:0.994
XMM/EPIC image 54 ks (MOS) 16 ks (pn) Belsole et al. 2004
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
Point source + model = 0.66, rc = 200 kpcevidence of extended emissionLX ~ 5.9 x 1043
X-ray spectrum: 3 componentsS = 1.5±1.0 from ChandraNH =4.9 1023 cm-2; H = 1.4±0.35kT = 3.6+ 14.1 -1.8 keV; LX = 8.3±1.8 x 1043 erg/s
3C184
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
HST (Deltorn et al. 97)Excess of galaxies + 11 galaxies at z~1Arc detection and mass within arc ~2 x 1013 Msun
3C184
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
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
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
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
Bolometric LX (1043 erg/s)
N
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
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)
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
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
caveatIt is difficult to separate components!
Elena BelsoleUniversity of Bristol
Distant clusters of GalaxiesRingberg Workshop
24-28 October 2005
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?