The luminous X-ray hotspot in 4C 74.26:

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The luminous X-ray hotspot in 4C 74.26 jet
dynamics at work
Mary Erlund Institute of Astronomy, Cambridge, UK

A.C. Fabian, K.M. Blundell, C. Moss and D.R.
Ballantyne
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4C 74.26 z0.104
Largest known radio quasar 10' on sky (1.1
Mpc)? deprojected length (45 deg) at least
1.6Mpc
Grey-scale 1.47 GHz radio data from VLA B-array
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Southern side of 4C 74.26
Grey-scale - 1.47 GHz radio - VLA B-array
Green contours - XMM EPIC-pn data - 0.5-10 keV
band - 34 ks observation
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Hotspot offset

• Grey-scale
• - Chandra data
• - 0.5-7keV band
• - 70ks with grating

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Hotspot offset

• Grey-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 offset

• Grey-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 offset

• Grey-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 profile

• black 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 gt 120 Typical Type I AGN
X/O lt10 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, ? 1.54 /-
0.1 (i.e. Spectral index, a 0.54 /-
0.1)? consistent with - other hotspots
and - models of shock acceleration (H
eavens 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
X-ray
Jet
Core
Radio
CMB
Georganopoulos Kazanas 2004
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Spine-sheath model
Faster but less massive spine
X-ray spine
core
Slower but more massive sheath
Radio sheath
e.g. Chiaberge et al. 2000
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Dentists drill model
Radio Old
Old jet path
Core
New jet path
X-ray New
Scheuer 1982
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Implications of relativistic jet models

• Relativistic decelerating flow and sheath model
• Implies jet is relativistic (G2) over extremely
  large distances (gt 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