Winged and X-shaped radio galaxies Gijs Verdoes Kleijn OmegaCEN / Kapteyn Astronomical Institute University of Groningen, NL Teddy Cheung (NASA/Goddard, USA), Hermine Landt (Univ. Melbourne, Australia), Andres Jordan (Univ. Catolica, Chile), Stephen Healy (Stanford, USA)

Outline Intro “winged” and X-shaped radio galaxies Sample Observations and models/scenarios Are they important for understanding (radio) galaxy evolution? Sample Preliminary results

Winged and X-shaped radio galaxies Winged population ~7-10% of 3CR radio galaxy population (Leahy & Williams 1984) Radio morphology Primary radio lobes Secondary pair of lobes/wings Canonically: size secondary/primary>0.8 Additional lobes show no signs of active jet or hotspot A subset has well defined X-shape 3C403 (Kraft et al. 2005)

Winged radio galaxies, examples NGC326; Ekers+78, Murgia+01 3C223.1; Dennett-Thorpe+02 Mixed bag? From Reynolds+09

Formation models Two classes of model Jet orientation fixed: Jets energize active lobes Wings created by “blowout” of the backflow (overpressure / buoyancy) Jet re-orientation: Rapid realignment of jets leaving fossil lobes in old direction and new active lobes (trealign<106yr) Change of spin axis BH/accretion disk SMBH merger Scheuer (1974) See also Dennett-Thorpe et al. (2002), Merritt & Ekers (2002); Komossa (2003)

Hydrodynamical model favored? Pro: Wings roughly align with optical (Capetti+02) and X-ray minor axis (Hodge-Kluck+10) Con: Winged FRIs exist However, inner FRIIs sometimes(/often?) present (e.g., Saripalli+09) + more arguments (also Blundell: fading argument?)

3C403 (Kraft et al. 2005) Courtesy Reynolds, Hodges-Kluck 2009 Chandra ACIS-S Courtesy Reynolds, Hodges-Kluck 2009

Optical/radio/X-ray orientations Radio/opt in Winged galaxies Main lobes Wings Hodges-Kluck+. (in prep) Saripalli+09

Xs+wings relevant for (radio) galaxy evolution? Merger rate: What fraction of winged RGs is due to hydrodynamics? How can we isolate the X-shaped radio galaxies which are most plausibly NOT due to hydrodynamic effects?: No opt/radio alignment ? 1/T_merger=Fraction(mergers)*fraction(winged)/T_winged (Merritt+Ekers02) Standard evolutionary phase?: What makes a RG to become a winged RG? Coincidental alignment of active jet with long-axis host/ISM/IGM X-ray ISM/IGM?: deep X-ray imaging required (not there yet?) grav. potential?: constrain triaxial shape of hosts of X-shaped radio sources Accretion mode?: spectroscopy Why do X-shaped radio galaxies straddle the FRI/FRII boundary? Blow-out relevant for SF quenching?

Winged RG sample selection Eyeball inspection of FIRST survey of sources with: Sensitivity to low-SBrightness features Dynamic range >40:1 (peak>5mJy/beam) Resolved structures R_maj>15arcsec and R_min > 5arcsec 1648 candidates: Bronze sample: 100 candidate wings, Silver sample: 50 quite certain + 14 known galaxies (2007) (WING/RG fraction ~4-10%)

Bronze sample

Spectroscopy for 53 of silver sample in hand Primary goal: Redshifts Emi-line fluxes

General sample properties Cheung,Landt,VK, Jordan+09 X=literature O=new Why do winged RGs straddle FRI/FRII boundary?

Sneak preview (aka very preliminary results)

Comparing Halpha in 3CR and winged RGs 3CR from Buttiglione, Capetti+09 No difference Normal / Winged RGs?

OIII/Hbeta ratio 3CR from Buttiglione, Capetti+09

Equivalent widths Unexpected high fraction of weak-lined sources? Filled: NLR+BLR Open: only NLR Unexpected high fraction of weak-lined sources?

FRI vs FRII or strong vs weak-lined? Filled/open: strong/weak Triangles: upper-limits OIII/OII

Conclusions X-shaped/winged RGs Get bit too little attention for their potential as probes of RLAGN evolution / IGM+ISM properties Probably many due to hydrodynamics Multi-lambda demographics needed to go further >doubled (in 2007) the sample of winged RGs Cheung+ 2007, AJ, 133, 2097 Spectra at hand, being analyzed Cheung, Landt, VK, Jordan, Healy, 2009, ApJS, 181, 548 Landt, VK…., 2010 in preparation