1994/03/24 by Matthias Bartelmann, Peter Schneider, Bartelmann, Matthias +3
Mathematics · Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Statistical and numerical algorithms #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9403055
23 pages, uuencoded compressed postscript including figures; preprint MPA 796
arxiv created 1994/03/24 · openalex publication_date 1994/03/24 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We announce the detection of correlations on angular scales of \ga10' between optically bright, high-redshift, radio-loud QSOs with diffuse X-ray emission seen by ROSAT in the \it All-Sky Survey. These correlations reach significance levels of up to 99.8%. A comparison of the results with a sample of control fields, bootstrapping analyses, and Kolmogorov-Smirnov tests provide unambiguous support for the statistical significance of the correlations found. We argue that the detected enhanced diffuse X-ray emission is in the foreground of the QSOs, and that it is probably due to galaxy clusters which magnify the QSOs by their gravitational lensing effect, thereby giving rise to a magnification bias in the background source sample. A comparison of the results presented below with correlations previously found between the same QSO sample and either Lick or IRAS galaxies provides further evidence for this interpretation, and identifies positions in the sky where weak gravitational lensing may be detected by searching for coherent distortions of background galaxy images.