Morphology and Surface Brightness Evolution of z\sim1.1 Radio Galaxies

Nathan Roche; Stephen Eales; Steve Rawlings

doi:10.1046/j.1365-8711.1998.01494.x

paper

Morphology and Surface Brightness Evolution of z\sim1.1 Radio Galaxies

arXiv:astro-ph/9707100 · doi:10.1046/j.1365-8711.1998.01494.x

Abstract

We use $K - ban d ima g in g t o in v es t i g a t e t h e an g u l a r s i z e an d m or p h o l o g y o f 106 C r a d i o g a l a x i es, a t r e d s hi f t s$ 1\leq z\leq 1.4 $. T w o a pp e a r t o b e u n d er g o in g m er g er s, an o t h er co n t ain s tw o in t e n s i t y p e ak s a l i g n e d w i t h t h er a d i o j e t s, w hi l e t h eo t h er se v e na pp e a r co n s i s t e n tw i t hb e in g n or ma l e l l i pt i c a l s in t h eK - ban d . I n t r in s i c ha l f - l i g h t r a d iia r ees t ima t e df r o m t h e a r e a so f e a c h r a d i o g a l a x y ima g e ab o v e a ser i eso f t h r es h o l d s . T h e 6 C g a l a x y r a d iia r e f o u n d t o b es i g ni f i c an tl y s ma l l er t han t h oseo f t h e m or er a d i o l u min o u s 3 C R g a l a x i es a t s imi l a r r e d s hi f t s . T hi s w o u l d in d i c a t e t ha tt h e hi g h er m e an K - ban d l u min os i t y o f t h e 3 C R g a l a x i esr es u l t s f r o ma d i f f er e n ce in t h es i z eo f t h e h os t g a l a x i es, an d n o t so l e l y f r o ma d i f f er e n ce in t h e p o w er o f t h e a c t i v e n u c l e i . T h es i z e - l u min os i t y r e l a t i o n o f t h e$ z\sim 1.1 $6 C g a l a x i es in d i c a t es a 1.0 - - 1.8 ma g e nhan ce m e n t o f t h er es t - f r am e R - ban d s u r f a ce b r i g h t n essr e l a t i v e t oe i t h er l oc a l e l l i pt i c a l so f t h es am es i z eor F R I I r a d i o g a l a x i es a t$ z<0.2 $. T h e 3 C R g a l a x i es a t$ z\sim 1.1 $s h o w a co m p a r ab l ee nhan ce m e n t in s u r f a ce b r i g h t n ess . T h e m e an r a d i u so f t h e 6 C g a l a x i ess ug g es t s t ha tt h ey e v o l v e in t oe l l i pt i c a l so f$ L\sim L^* $l u min os i t y, an d i sco n s i s t e n tw i t h t h e i r l o w r e d s hi f t co u n t er p a r t s b e in g r e l a t i v e l y s ma l l F R I I g a l a x i es, a f a c t or$ \sim 25 $l o w er in r a d i o l u min os i t y, or s ma l l F R I g a l a x i es a f a c t or o f$ \sim 1000$ lower in radio luminosity. Hence the 6C radio galaxies may undergo at least as much optical and radio evolution as the 3CR galaxies.

17 pages, 7 postscript figures, TEX, submitted to MNRAS

Morphology and Surface Brightness Evolution of z\sim1.1 Radio Galaxies

Abstract

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