A Chandra Survey of Quasar Jets: Latest Results Jonathan Gelbord H.L. Marshall (MIT); D.A. Schwartz (SAO); D.M. Worrall & M. Birkinshaw (U. Bristol); J.E.J. Lovell, L. Godfrey & D.L. Jauncey (CSIRO); E.S. Perlman (FIT); M. Georganopoulos (UMBC); D.W. Murphy (JPL)

A Chandra Survey of Quasar Jets: Latest Results A Progress Report Jonathan Gelbord H.L. Marshall (MIT); D.A. Schwartz (SAO); D.M. Worrall & M. Birkinshaw (U. Bristol); J.E.J. Lovell, L. Godfrey & D.L. Jauncey (CSIRO); E.S. Perlman (FIT); M. Georganopoulos (UMBC); D.W. Murphy (JPL)

Motivating the survey Starting point: PKS First Chandra celestial target Jet X-ray flux could not be describe as a simple extension of the radio synch or SSC (Schwartz et al 2000)

Motivating the survey Starting point: PKS First Chandra celestial target Jet X-ray flux could not be describe as a simple extension of the radio synch or SSC (Schwartz et al 2000) IC-CMB suggested (Tavecchio et al 2000, Celotti et al 2001) We want to determine whether this is representative of FR II jets.

Motivating the survey Starting point: PKS First Chandra celestial target Jet X-ray flux could not be describe as a simple extension of the radio synch or SSC (Schwartz et al 2000) IC-CMB suggested (Tavecchio et al 2000, Celotti et al 2001) We want to determine whether this is representative of FR II jets.

Motivating the survey Starting point: PKS IC-CMB suggested (Tavecchio et al 2000, Celotti et al 2001)

Motivating the survey Survey objectives: Are X-ray bright FR II jets common? What mechanism(s) generate this emission? What are the underlying physical conditions?

Motivating the survey Survey objectives: Are X-ray bright FR II jets common? What mechanism(s) generate this emission? What are the underlying physical conditions? To establish the distribution of these properties requires a large sample.

Conducting the survey Survey strategy: Identify FR II systems that may resemble PKS Take Chandra snapshots to… –establish how many are X-ray bright –identify targets for further study Multiwavelength follow-up program: –obtain new, higher-resolution radio maps –deep optical (and IR) photometry –deeper X-ray observations of selected targets

Conducting the survey Sample definition: Drawn from flux-limited radio surveys (VLA: Murphy, Brown & Perley 1993; ATCA: Lovell 1997) Flat-spectrum radio sources with extended structure Uncertain whether flux or morphology would better identify X-ray bright jets 56 sample members meet either or both criteria: –Flux limit in extended flux (30 sources) –One-sided jet-like morphology (47 sources)

Survey status 1st 20 Chandra snapshots + new radio maps (Marshall et al 2005) 19 more sample members now available: –10 more snapshots –9 from Chandra archives (many from Sambruna et al 2002, 2004) Plus follow-up observations with Hubble, Spitzer, Magellan

Results to date X-ray jet demographics Detections in 24/39 sources (62%) S x /S r flux ratio R spans two orders of magnitude amongst X-ray detected jets ⇒ cannot easily predict S x from S r measurements Detection rate amongst 19 brightest sources –14/19 overall (74%) ⇒ radio bright more likely detected –of these, 12 also meet morphological selection criteria; 10/12 (83%) detected ⇒ geometry an important factor

Results to date X-ray emission process: IC-CMB? Optical jet flux often low; indicative of IC. IC-CMB?? A test: IC-CMB predicts R ∝ (1+z) 3 , where  is the radio spectral index PKS SED: optical flux limits rule out extension of radio synchrotron continuum to X-rays.

Results to date The predicted redshift dependence is not found. 1+z  rx

Results to date 1+z  rx 0.55 < z < 0.95: mean  rx = 0.99 ± 0.02 z > 0.95:mean  rx = 0.96 ± 0.04

Results to date A more sensitive test: Assuming  rx ∝ (1+z) a, best fitting a = 0.5 ± 2.0 (90% confidence) a > 3.5 ruled out with 3-  confidence This potentially rules out IC-CMB models, unless either cosmological evolution or selection effects cause a systematic correlation with z. We are looking into this…

Summary Findings: ~ 60% of FR II quasar jets are strong X-ray emitters Jet geometry is a factor in the X-ray detectability Low optical fluxes suggest IC X-ray emission The redshift dependence of the X-ray/radio flux ratio predicted by IC-CMB is ruled out Further survey work in progress: Test possible interpretations of redshift correlation Incorporate geometrical constraints from VLBI structural data Establish range of physical jet properties within our sample …plus in-depth follow-up work on selected targets (see, e.g., talk by D. Schwartz on PKS )