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X-shaped Radio Galaxies

What do. X-shaped Radio Galaxies. have to say about. Radio-Mode Feedback?. Edmund Hodges-Kluck. Chris Reynolds (UMd), Teddy Cheung (NRL), Cole Miller (UMd), Marc Pound (UMd). Clusters & Groups in the Chandra Era. Agenda. What are X-shaped Radio Galaxies?.

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X-shaped Radio Galaxies

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  1. What do X-shaped Radio Galaxies have to say about Radio-Mode Feedback? Edmund Hodges-Kluck Chris Reynolds (UMd), Teddy Cheung (NRL), Cole Miller (UMd), Marc Pound (UMd) Clusters & Groups in the Chandra Era

  2. Agenda What are X-shaped Radio Galaxies? What are X-shaped Radio Galaxies? The origin of XRGs XRGs and Ghost Cavities

  3. Hot Spots Lobes Jets “Normal” Double-Lobed (FR II) Radio Galaxies X-shaped Radio Galaxies (~5% of RGs)

  4. Long, Inactive Lobes (Leahy+84) Centro-symmetric(Leahy+84) Weak FR IIs/Strong FR Is (Cheung+09) Higher than average SMBH masses(Mezcua+10) Possibly related to “winged” RGs(Cheung 07) Jets co-aligned with host major axis(Capetti+02)

  5. What are X-shaped Radio Galaxies? The origin of XRGs XRGs and Ghost Cavities

  6. Fossil Relics • Precession (Dennett-Thorpe+02) • SMBH merger (Merritt+02) • Accretion torque (Rees+82) • Redirected Lobes • Buoyant Backflow (Worrall+95, Leahy+84) • Overpressured Cocoon (Capetti+02) • Binary AGN • Twin jet pairs (Lal+Rao 05)

  7. Do the data support a rolefor XRG environments? X-ray Imaging Is the hydrodynamichypothesis plausible? Hydrodynamic Simulations Radio lobes are bubbles in a tenuous, hot (T > 107 K) plasma If jets/lobes interact with surroundings, it will be with the IGM/ICM RadioX-ray

  8. Hodges-Kluck+2010a ApJ…710.1205 ISM IGM ΔPA = 0 Coaligned with major axis ΔPA = 90 Coaligned with minor axis

  9. Hodges-Kluck+Reynolds 2011ApJ…733…58

  10. X-ray observations and hydrodynamic simulations support a role for XRG environments Unclear whether proposed hydrodynamic models really work At least one XRG looks like a spin-flip: 4C +00.58 (Hodges-Kluck+2010b ApJ…717..L37) Review: Gopal-Krishna+2010 arXiv/1008.0789

  11. What are X-shaped Radio Galaxies? The origin of XRGs XRGs and Ghost Cavities

  12. What Happens to Dead Radio Galaxies? • How do radio galaxies heat cores? • PdV energy in cavities vs. jet-driven shocks (e.g. Reynolds+02), disk winds (e.g. Gaspari+11) • Maybe they don’t directly? Hybrid conduction models; Stirring (Ruszkowski+Oh 2010) Ghost cavities reported in a number of systems (e.g. Perseus, NGC 741, A2597) Cavities ubiquitous in groups; little correlation with radio emission (Dong+10), but only seen near cores (c.f. Giacintucci+11) Cavity evolution poorly understood

  13. Inactive Lobes 100 kpc • Long (up to >100 kpc) • Usually in groups • Either fossils or evolve in response to environment • Presumably have cavities • Bright at 1.4 GHz

  14. Only 2 XRGs have X-ray exposures of ~100ks: Chip Edge Jet Both have significant cavities associated with wings (highlighted in unsharp mask images)

  15. Proof of concept: NGC 326

  16. 0.3-3 keV 3-8 keV The east wing cavity is ~100 kpc from the core and is probably over 50 Myr old The active outburst may itself be associated with cavities and a shock front…

  17. kT (apec 1-T 0.3-5 keV) Surface Brightness • Temperature does not follow surface brightness • Density, temperature changes behind front consistent with Mach ~2 shock

  18. Raw 0.3-5 keV binned 16x Unsharp Mask • What can we know? • Age from several avenues • Rough size/energy • Gross magnetic structure (Murgia+01) • T/P of surrounding gas • What can’t we know (yet)? • Filling factor/entrainment • Cap of material? • Old shocks/sound waves? • Bubble shredding? • Detailed synchrotron map

  19. Need higher S/N!

  20. Summary XRGs are an interesting subclass of double-lobed radio galaxies whose origin is mysterious XRGs illuminate hard-to-find “dead” radio bubbles far from the AGN Higher S/N required to study cavities (XMM? Astro-H?)

  21. 3C 388 3C 305 3C 264 3C 171 3C 465 3C 272.1 3C 120

  22. Old cavities re-energized by restarted AGN in hydro simulations Jet Axis False Synchrotron (GHz)

  23. Wing length as a function of atmosphere parameters Wing length as a function of jet parameters

  24. 4C +00.58

  25. Case in Point: 4C +00.58 Optical Radio jet aligned with host minor axis, wings very long relative to cocoon Radio

  26. Case in Point: 4C +00.58 Optical “Stellar shell” suggests recent minor galaxy merger X-ray cavities aligned with wings and major axis suggest recent jet activity along other axes Long wings preclude hydrodynamic deflection—they must be fewer than 40 Myr old X-ray unsharp mask

  27. Case in Point: 4C +00.58  ~ 1.6 The bent jet, seen in radio (VLA + CARMA) and X-ray (Chandra), appears to be cooling rapidly at the tip: has it been dragged?  ~ 0.6 Hypothesis: A minor merger activated the radio galaxy along one axis, then accretion torque or coalescence of a SMBH binary moved the jet.

  28. Model Testing with Timescales Myr (measured from X-rays, radio) • Minimum wing age (transonic expansion) • Maximum Cocoon Age (transonic expansion) • Synchrotron cooling time (wing decay) • X-ray free-free (cavity wall) cooling time Myr (measured from X-rays, radio) Myr (measured from radio) Myr (measured from X-rays)

  29. Did the wings form hydrodynamically? • Transonic expansion time (minimum age): • texp ~ lwing/cs~ 90 Myr • tsync ~ 40 Myr [1 GHz] • Cocoon should expand faster than wings, and cs is constant in the region—strong projection ruled out by OII/OIII ratio • Cocoon is well defined • Cocoon texp < 35 Myr • Cavities misaligned with the jets unexplained SDSS r+g

  30. Timescales • Sound speed (pressure crossing time) • Temperature and emission-weighted density from apec fits to the 0.3-3 keV spectrum in Xspec • kT ~ 1.0 keV within 40 kpc (approximately isothermal) • Synchrotron (wing) cooling time • Equipartition B-field assumed; use radio flux and volume of wings/lobes, with spectral index (~0.7) determined from photometry • With B in hand, synchrotron frequency measured at 1.4 GHz, so wing lifetime is for electrons radiating at 1.4 GHz km/s Myr (measured from radio)

  31. Timescales • X-ray free-free (cavity wall) cooling time • Temperature and emission-weighted density from apec fits to the 0.3-3 keV cavity wall spectrum in Xspec • Assume a typical bremsstrahlung cooling function (T0.5) • Maximum Cocoon Age (transonic expansion) • Cocoons associated with bow shocks, powerful jets, so supersonic expansion (several times ambient sound speed) assumed even in weaker radio galaxies • Trans- or sub-sonic expansion unlikely to produce a cocoon, but possibly intermittent jets… Myr (measured from X-rays) Myr (measured from X-rays, radio)

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