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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
&
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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
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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
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Hotspot offsetGrey-scale:- Chandra data- 0.5-7keV band- ~70ks with grating
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Hotspot offsetGrey-scale:- Chandra data- 0.5-7keV band- ~70ks with grating Blue contours:- VLA B array at 1.47GHz- 5.1” resolution
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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
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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
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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
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Background AGN?
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Image:- optical data - R = 24.3mag limit.
White contours;- VLA B-array
Yellow circle:- radius 3 arcsec - X-ray hotspot
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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
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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)
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Models for X-ray / radio hotspot
offset
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Up-scattering of the CMB in a relativistic decelerating flow
Georganopoulos & Kazanas 2004
Jet X-ray
Radio
CMB
Core
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Spine-sheath model
e.g. Chiaberge et al. 2000
X-ray: spine
Radio: sheath
Slower but more massive sheath
Faster but less massive spinecore
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Dentist’s drill model
Scheuer 1982
X-ray: New
Radio: Old Old jet
path
New jet path
Core
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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.
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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
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Thank you