The luminous X-ray hotspot in 4C

74.26:

jet dynamics at workMary Erlund

Institute of Astronomy, Cambridge, UK

A.C. Fabian, K.M. Blundell, C. Moss and D.R. Ballantyne

&

Grey-scale:1.47 GHz radio data from VLAB-array

4C 74.26z=0.104Largest known radio quasar

10' on sky (1.1 Mpc)

deprojected length (45 deg)at least 1.6Mpc

Green contours: - XMM EPIC-pn data - 0.5-10 keV band- 34 ks observation

Southern side of 4C 74.26

Grey-scale:- 1.47 GHz radio- VLA B-array

Hotspot offsetGrey-scale:- Chandra data- 0.5-7keV band- ~70ks with grating

Hotspot offsetGrey-scale:- Chandra data- 0.5-7keV band- ~70ks with grating Blue contours:- VLA B array at 1.47GHz- 5.1” resolution

Hotspot offsetGrey-scale:- Chandra data- 0.5-7keV band- ~70ks with grating Blue contours:- VLA B array at 1.47GHz- 5.1” resolution

Red contours:- VLA A array at 1.49GHz- 1.7” resolution

Hotspot offsetGrey-scale:- Chandra data- 0.5-7keV band- ~70ks with grating Blue contours:- VLA B array at 1.47GHz- 5.1” resolution

Red contours:- VLA A array at 1.49GHz- 1.7” resolution

Magenta contours:- MERLIN at 1.66GHz- 0.2” resolution

Hotspot profileblack line:- Chandra- 0.5-7keV band- Gaussian-smoothed so 1.5” resolution

red line:- VLA A array- 1.49GHz- 1.7” resolution

magenta line:- MERLIN - 1.66GHz- 0.2” resolution

Background AGN?

Image:- optical data - R = 24.3mag limit.

White contours;- VLA B-array

Yellow circle:- radius 3 arcsec - X-ray hotspot

Constraints from optical data

X-ray to optical flux ratio: X/O > 120

Typical Type I AGN: X/O <10

Extreme X-ray / optical (EXO) AGN(very rare): X/O ~ 100

If an EXO it is much more X-ray bright than any detected

X-ray spectrum not that of an EXO

Luminous X-ray hotspot

4C 74.26: LX(0.5-10keV) ~ 2.2 x 1042 ergs-1

Pictor A: LX(0.5-10keV) ~ 1.6 x 1042

ergs-1

Cygnus A: LX(0.5-10keV) ~ 1.8 x 1042 ergs-1

(Wilson et al. 2001, Wilson et al. 2000)

Photon index, Г = 1.54 +/- 0.1 (i.e. Spectral index, α = 0.54 +/- 0.1)

consistent with:- other hotspots and - models of shock

acceleration(Heavens & Drury 1988; Achterberg et al.

2001)

Models for X-ray / radio hotspot

offset

Up-scattering of the CMB in a relativistic decelerating flow

Georganopoulos & Kazanas 2004

Jet X-ray

Radio

CMB

Core

Spine-sheath model

e.g. Chiaberge et al. 2000

X-ray: spine

Radio: sheath

Slower but more massive sheath

Faster but less massive spinecore

Dentist’s drill model

Scheuer 1982

X-ray: New

Radio: Old Old jet

path

New jet path

Core

Implications of relativistic jet models

Relativistic decelerating flow and sheath model :

Implies jet is relativistic (Γ~2) over extremely large distances (> 800kpc).

Limitation of relativistic decelerating flow model :

If the source was aligned closer to the line of sight, X-ray hotspot would be even brighter: it is already a very bright hotspot.

Conclusions

The southern X-ray hotspot in 4C 74.26 is X-ray luminous

The X-ray / radio offset is 10” or 19kpc projected onto the sky

The models that can reproduce what we see have important consequences for jet dynamics

In order to distinguish between them we need Chandra imaging of the hotspot complex and high quality optical data

Thank you