Winged and X-shaped radio galaxies

Gijs Verdoes KleijnOmegaCEN / 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)

OutlineOutline

Intro “winged” and X-shaped radio galaxies Observations and models/scenarios Are they important for understanding (radio) galaxy

evolution?

Sample Preliminary results

Intro “winged” and X-shaped radio galaxies Observations and models/scenarios Are they important for understanding (radio) galaxy

evolution?

Sample Preliminary results

Winged and X-shaped radio galaxiesWinged 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

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

From Reynolds+09

Mixed bag?

Formation modelsFormation models

Two classes of model1. Jet orientation fixed:

Jets energize active lobes Wings created by “blowout”

of the backflow (overpressure / buoyancy)

2. 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

Two classes of model1. Jet orientation fixed:

Jets energize active lobes Wings created by “blowout”

of the backflow (overpressure / buoyancy)

2. 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

See also Dennett-Thorpe et al. (2002), Merritt & Ekers (2002); Komossa (2003)

Scheuer (1974)

Hydrodynamical model favored?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?)

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)

Chandra ACIS-S

Courtesy Reynolds, Hodges-Kluck 2009

Optical/radio/X-ray orientationsOptical/radio/X-ray orientations

Main lobesWings

Radio/opt in Winged galaxies

Saripalli+09

Hodges-Kluck+. (in prep)

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%)

Bro

nze

sam

ple

Spectroscopy for 53 of silver sample in hand

Primary goal:•Redshifts•Emi-line fluxes

General sample properties

• Why do winged RGs straddle FRI/FRII boundary?

Che

ung,

Land

t,V

K,

Jord

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09

X=literatureO=new

Sneak preview (aka very preliminary results)

Comparing Halpha in 3CR and winged RGs

• No difference Normal / Winged RGs?

3CR from Buttiglione, Capetti+09

OIII/Hbeta ratio3CR from Buttiglione, Capetti+09

Equivalent widths

• Unexpected high fraction of weak-lined sources?

Filled: NLR+BLROpen: only NLR

FRI vs FRII or

strong vs weak-lined?Filled/open: strong/weakTriangles: 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