
TY  - JOUR
A1  - Croom, Scott M. 
T1  - QSO-Galaxy Correlations: Lensing or Dust?
JF  - Publications of the Astronomical Society of Australia
JO  - Publ. Astron. Soc.  Aust.
Y1  - 2001
VL  - 18
IS  - 2
SP  - 169
EP  - 171
KW  - gravitational lensing &#8212; galaxies: statistics &#8212; quasars: general &#8212; dust, extinction
UR  - https://doi.org/10.1071/AS01012 
N2  - Received 2001 January 25, accepted 2001 May 3 We present evidence for an anti-correlation between faint QSOs and B &#60; 23 galaxies.A sample of 192 QSOs in a 2.5 deg2 area has been imaged using the Isaac Newton Telescope Wide-Field Camera. The cross-correlation signal is of a similar amplitude to the galaxy auto-correlation function at the limit of B &#60; 23, but is negative in sign. As fainter galaxies are selected the negative correlation signal becomes less significant, until the signal is effectively zero at B &#60; 26. We propose two alternate explanations for the observed effect. The first is gravitational lensing of the faint background QSOs, which have a flat number count slope. However, the lensing signal is significantly higher than expected in conventional models. The second possibility is that inter-galactic dust absorption is responsible. A reddening of only E(B - V) ~ 0.02 is required to produce the observed correlation. The large 2dF and SDSS QSO surveys should allow a definitive solution to the question of QSO&#8211;galaxy correlations. 
ER  -

