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The time delay of the quadruple quasar RX J0911.4+0551

Jens Hjorth·Ingunn Burud·Andreas O. Jaunsen·Paul L. Schechter·Jean-Paul Kneib·Michael I. Andersen·Heidi Korhonen·Jacob W. Clasen·A. Amanda Kaas·Roy Østensen·Jaan Pelt·Frank P. Pijpers
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Abstract

We present optical lightcurves of the gravitationally lensed components A (=A1+A2+A3) and B of the quadruple quasar RX J0911.4+0551 (z = 2.80). The observations were primarily obtained at the Nordic Optical Telescope between 1997 March and 2001 April and consist of 74 I-band data points for each component. The data allow the measurement of a time delay of 146 +- 8 days (2 sigma) between A and B, with B as the leading component. This value is significantly shorter than that predicted from simple models and indicates a very large external shear. Mass models including the main lens galaxy and the surrounding massive cluster of galaxies at z = 0.77, responsible for the external shear, yield H_0 = 71 +- 4 (random, 2 sigma) +- 8 (systematic) km/s/Mpc. The systematic model uncertainty is governed by the surface-mass density (convergence) at the location of the multiple images.

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Jens Hjorth, Ingunn Burud, Andreas O. Jaunsen, Paul L. Schechter, Jean-Paul Kneib, Michael I. Andersen, Heidi Korhonen, Jacob W. Clasen, A. Amanda Kaas, Roy Østensen, Jaan Pelt, Frank P. Pijpers. 2002-05-08. The time delay of the quadruple quasar RX J0911.4+0551. https://doi.org/10.1086/341603

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