Dr Katherine InskipMontse Villar-Martín (IAA Granada)

Clive Tadhunter, Joanna Holt, Dan Dicken (Sheffield)

Raffaella Morganti (ASTRON)

Friday 20th October 2006

Extended Emission Line Regions:

Nature, origins & implications

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The data PKS1932-46

VIMOS data: ~210 minutes over 3 nights Includes useful emission lines:

H – [SII]6731 PKS2250-41

VIMOS data: ~200 minutes over 4 nights

(and several months…!) Includes useful emission lines:

[OII]3727 – [SII]6731 Long-slit optical FORS1 spectrum at PA~70° (offset ° (offset

from radio axis)from radio axis) Also have Spitzer photometry of both sources, and

optical/IR imaging

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So, what can we learn?

Distribution of line-emitting material Ionization state of the gas Density and temperature diagnostics Gas kinematics – relative velocities and line widths

Pros: all the usual tools/results of narrow-band imaging and long-slit spectra, plus the ability to tune into regions of interest.

Cons: Targeted observations give better depth, and a less restrictive FOV.

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FRII radio galaxy at z=0.231FRII radio galaxy at z=0.231RA: 19RA: 19hh3535mm56.656.6ss : -46: -46°°202041.841.8 (J2000) (J2000)

PKS1932–464

PA -9PA -9° spectra ° spectra (63° offset from radio (63° offset from radio axis) show 150kpc axis) show 150kpc knotty, knotty, star-forming EELR.star-forming EELR.

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IFU fly-through: PKS1932-46

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IFU fly-through: PKS1932-46

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Host galaxy at z=0.23; extension to E, +further emission

just beyond radio lobe More blobs in surrounding IGM,

including star-forming blobs to south

Possible companion galaxy to NE

PKS1932-46:– fitting the [OIII] emission

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PKS1932-46: – fitting the [OIII] emission

Line width Line shift

Northern blob bright in [OII]3727 shocks?… but from what? Relative velocities vary by ~600kms-1… but generally line widths suggest

quiescent material. O and S line ratios consistent with ne~100cm-3 and T ~ few 104K.

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The companion galaxy… z=0.229 (cf. 0.231 for PKS1932-46) [OIII]/H ~1 star formation! Also, v. bright in Spitzer data. Narrow blueshifted emission around PKS1932-46 host galaxy

– same redshift as companion Obvious question: Is this an interacting system?

Did interaction trigger AGN activity? Clearly a very messy system!

24m 70m

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IFU fly-through: PKS2250-41

[OIII]5007 (left) and [OII]3727 (right)

FRII radio galaxy at z=0.308 RA: 22h53m03.1s : -40°5746 (J2000)

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IFU fly-through: PKS2250-41

[OIII]5007 (left) and [OII]3727 (right)

FRII radio galaxy at z=0.308 RA: 22h53m03.1s : -40°5746 (J2000)

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IFU fly-through: PKS2250-41

[OIII]5007 (left) and [OII]3727 (right)

FRII radio galaxy at z=0.308 RA: 22h53m03.1s : -40°5746 (J2000)

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PKS2250-41: – EELR Ionization State

As expected, we can clearly pinpoint shocked region near hotspot. Elsewhere, gas appears photoionized.

[OIII]5007Å

[OII]/[OIII] [OII]3727Å

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PKS2250-41:– EELR [OIII] kinematics

Most extreme line widths observed near AGN and along jet axis, not near hotspot.

Distant regions – narrow line widths. Apparent rotating structure. Similar kinematics observed in FORS1

spectrum

Narrow line regions (~150-220kms-1) with broad-ish (400-500kms-1) blue wings:

Observed near hotspots and towards centre of EELRIonization state suggests shocks/post-shock gas

Also see broadening on south side of EELR, seemingly unconnected with radio source kinematics/shock ionization

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Ionized gas pointing towards

the nearby galaxy

[OIII] image Cont. image

~ 12’’ or 54 kpc

FORS1 spectrum of PKS2250-41: – the very extended emission line region

[OIII] image, not continuum subtracted

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The faint emission in the western lobe:

Balmer absorption detected in companion galaxy

suggests similar redshifts

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Concluding thoughts…

Radio source/EELR interactions fairly well understood, but… Origin of EELR gas is not! Links with questions of AGN triggering and galaxy growth. Many similarities between PKS2250-41 and PKS1932-46:

Radio source strongly interacting with EELR Can we disentangle cause/effect when it comes to clumpy

IGM/halo material?

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Concluding thoughts… similarities cont.:

Strong potential for merger/interactions in local environment Both sources have close companions, and emission from

blobs lying well off the radio axis Gas kinematics – narrow FWHM at a variety of velocity

offsets Other activity:

Evidence for star formation in blobs Overall:

radio galaxy halos are interesting, unsettled environments, with a lot of physics going on – and it’s not just shocks!

Potential to greatly improve our understanding of the triggering process and links to interactions, and ongoing AGN-related feedback