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The luminous X-ray hotspot in 4C 74.26: jet dynamics at work

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. 4C 74.26 z=0.104. Largest known radio quasar 10' on sky (1.1 Mpc) ‏ deprojected length (45 deg)

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The luminous X-ray hotspot in 4C 74.26: jet dynamics at work

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  1. 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

  2. 4C 74.26 z=0.104 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

  3. 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 ksobservation

  4. Hotspot offset Grey-scale: - Chandra data - 0.5-7keV band - ~70ks with grating

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

  6. 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

  7. 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

  8. 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

  9. Background AGN?

  10. Image: - optical data - R = 24.3mag limit. White contours; - VLA B-array Yellow circle: - radius 3 arcsec - X-ray hotspot

  11. 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

  12. 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)‏

  13. Models for X-ray / radio hotspot offset

  14. Up-scattering of the CMB in a relativistic decelerating flow X-ray Jet Core Radio CMB Georganopoulos & Kazanas 2004

  15. 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

  16. Dentist’s drill model Radio: Old Old jet path Core New jet path X-ray: New Scheuer 1982

  17. 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.

  18. 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

  19. Thank you

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