HST Observations of the QSO pair Q1026-0045A,B

Patrick Petitjean; Jean Surdej; Alain Smette; Peter Shaver; Jan Muecket; Marc Remy

paper

HST Observations of the QSO pair Q1026-0045A,B

arXiv:astro-ph/9804242

Abstract

The spatial distribution of the Ly $α$ forest is studied using new HST data for the quasar pair Q~1026--0045 A and B at $z_{e m}$ = 1.438 and 1.520 respectively. The angular separation is 36 arcsec and corresponds to transverse linear separations between lines of sight of $\sim 300 h_{50}^{- 1}$ kpc ( $q_{o}$ = 0.5) over the redshift range 0.833 < z < 1.438. From the observed numbers of coincident and anti-coincident Ly $α$ absorption lines, we conclude that, at this redshift, the Ly $α$ structures have typical dimensions of $\sim 500 h_{50}^{- 1}$ kpc, larger than the mean separation of the two lines of sight. The velocity difference, $Δ V$ , between coincident lines is surprisingly small (4 and 8 pairs with $Δ V < 50 an d 200 k m / sr es p ec t i v e l y) . M e t a l l in esy s t e m s a r e p r ese n t a t$ z_{abs} $= 1.2651 an d 1.2969 in A,$ z_{abs} $= 0.6320, 0.7090, 1.2651 an d 1.4844 in B . I na dd i t i o n w e t e n t a t i v e l y i d e n t i f y a w e ak M g I I sy s t e ma t$ z_{abs} $= 0.11 in B . I t i sr e ma r k ab l e t ha tt h e$ z_{abs} $= 1.2651 sy s t e mi sco mm o n t o b o t h l in eso f s i g h t . T h esy s t e ma t$ z_{abs} $= 1.4844$ z_{abs} $= 1.4420 a l o n g t h e l in eo f s i g h tt o A w i t h co m pl e xv e l oc i t y p r o f i l e . W e d e t ec t a s t r o n g L y$ α $ab sor pt i o na l o n g t h e l in eo f s i g h tt o B r e d s hi f t e d b y o n l y 300 k m / sr e l a t i v e l y t o t h e a ssoc ia t e d sy s t e m . I t i s t e m pt in g t o in t er p r e tt hi s a s t h e p r ese n ceo f a d i s k o f r a d i u s l a r g er t han 300$ h^{-1}_{50}$ kpc surrounding quasar A.

4 pages, 2 figures, A&A Letter acccepted