The Environments of High Redshift QSOs

Soyoung Kim, Massimo Stiavelli, M. Trenti, C. M. Pavlovsky, S. G. Djorgovski, C. Scarlata, D. Stern, A. Mahabal, D. Thompson, M. Dickinson, N. Panagia, G. Meylan

November 2008

Abstract

We present a sample of $i{775} $- d r o p o u t c a n d i d a t e s i d e n t i f i e d i n f i v e H u b b l e A d v a n c e d C a m e r a f o r S u r v e y s f i e l d s c e n t e r e d o n S l o a n D i g i t a l S k y S u r v e y Q S O s a t r e d s h i f t$ zsim 6 $. O u r f i e l d s a r e a s d e e p a s t h e G r e a t O b s e r v a t o r y O r i g i n s D e e p S u r v e y (G O O D S) A C S i m a g e s w h i c h a r e u s e d a s a r e f e r e n c e f i e l d s a m p l e . W e f i n d t h e m t o b e o v e r d e n s e i n t w o f i e l d s, u n d e r d e n s e i n t w o f i e l d s, a n d a s d e n s e a s t h e a v e r a g e d e n s i t y o f G O O D S i n o n e f i e l d . T h e t w o e x c e s s f i e l d s s h o w s i g n i f i c a n t l y d i f f e r e n t c o l o r d i s t r i b u t i o n s f r o m t h a t o f G O O D S a t t h e 99$ i{775} $- d r o p o u t c o u n t s i n t h e f i v e f i e l d s i s b r o a d e r t h a n t h a t d e r i v e d f r o m G O O D S a t t h e 80$ i_{775}$-dropouts; its width cannot be explained by cosmic variance alone. Thus, QSOs seem to affect their environments in complex ways. We suggest the picture where the highest redshift QSOs are located in very massive overdensities and are therefore surrounded by an overdensity of lower mass halos. Radiative feedback by the QSO can in some cases prevent halos from becoming galaxies, thereby generating in extreme cases an underdensity of galaxies. The presence of both enhancement and suppression is compatible with the expected differences between lines of sight at the end of reionization as the presence of residual diffuse neutral hydrogen would provide young galaxies with shielding from the radiative effects of the QSO.

Type

Journal article

http://arxiv.org/abs/0805.1412v2