A Chandra Survey of Quasar Jets: Latest ResultsJonathan 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 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)

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.

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 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

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%)• 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

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 1202-262 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 1055+201)