A Chandra Survey of Quasar Jets: Latest Results

1. 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)

2. 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)

3. Motivating the survey • Starting point: PKS 0637-752 • 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)

4. Motivating the survey • Starting point: PKS 0637-752 • 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.

5. 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?

6. 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.

7. Conducting the survey • Survey strategy: • Identify FR II systems that may resemble PKS 0637-752 • 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

8. 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)

9. 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

10. Results to date • X-ray jet demographics • Detections in 24/39 sources (62%) • Sx/Sr flux ratio R spans two orders of magnitude amongst X-ray detected jets ⇒ cannot easily predict Sx from Sr 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

11. 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 Results to date PKS 1202-262 SED: optical flux limits rule out extension of radio synchrotron continuum to X-rays.

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

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

14. 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…

15. 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 1055+201)