TY - JOUR
T1 - The central image of a gravitationally lensed quasar
AU - Winn, Joshua H.
AU - Rusin, David
AU - Kochanek, Christopher S.
N1 - Funding Information:
Acknowledgements We thank S. Doeleman, D. Harris and P. Schechter for discussions, and J. Bullock for comments on the manuscript. J.N.W. acknowledges the support of the National Science Foundation (NSF) through an Astronomy and Astrophysics Postdoctoral Fellowship. The VLA is part of the National Radio Astronomy Observatory, an NSF facility operated under cooperative agreement by Associated Universities, Inc.
PY - 2004/2/12
Y1 - 2004/2/12
N2 - A galaxy can act as a gravitational lens, producing multiple images of a background object. Theory predicts that there should be an odd number of images produced by the lens, but hitherto almost all lensed objects have two or four images. The missing 'central' images, which should be faint and appear near the centre of the lensing galaxy, have long been sought as probes of galactic cores too distant to resolve with ordinary observations. There are five candidates for central images, but in one case the third image is not necessarily the central one, and in the others the putative central images might be foreground sources. Here we report a secure identification of a central image, based on radio observations of one of the candidates. Lens models using the central image reveal that the massive black hole at the centre of the lensing galaxy has a mass of <2 × 108 solar masses (M⊙), and the galaxy's surface density at the location of the central image is > 20,000M⊙pc-2, which is in agreement with expections based on observations of galaxies that are much closer to the Earth.
AB - A galaxy can act as a gravitational lens, producing multiple images of a background object. Theory predicts that there should be an odd number of images produced by the lens, but hitherto almost all lensed objects have two or four images. The missing 'central' images, which should be faint and appear near the centre of the lensing galaxy, have long been sought as probes of galactic cores too distant to resolve with ordinary observations. There are five candidates for central images, but in one case the third image is not necessarily the central one, and in the others the putative central images might be foreground sources. Here we report a secure identification of a central image, based on radio observations of one of the candidates. Lens models using the central image reveal that the massive black hole at the centre of the lensing galaxy has a mass of <2 × 108 solar masses (M⊙), and the galaxy's surface density at the location of the central image is > 20,000M⊙pc-2, which is in agreement with expections based on observations of galaxies that are much closer to the Earth.
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U2 - 10.1038/nature02279
DO - 10.1038/nature02279
M3 - Article
C2 - 14961114
AN - SCOPUS:1342283114
SN - 0028-0836
VL - 427
SP - 613
EP - 615
JO - Nature
JF - Nature
IS - 6975
ER -