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A new radio double lens from CLASS: B1127+385

Koopmans, L. V. E. and de Bruyn, A. G. and Marlow, D. R. and Jackson, N. and Blandford, R. D. and Browne, I. W. A. and Fassnacht, C. D. and Myers, S. T. and Pearson, T. J. and Readhead, A. C. S. and Wilkinson, P. N. and Womble, D. (1999) A new radio double lens from CLASS: B1127+385. Monthly Notices of the Royal Astronomical Society, 303 (4). pp. 727-735. ISSN 0035-8711. doi:10.1046/j.1365-8711.1999.02342.x.

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We present the discovery of a new gravitational lens system with two compact radio images separated by 0.701 ± 0.001 arcsec. The lens system was discovered in the Cosmic Lens All Sky Survey (CLASS) as a flat-spectrum radio source. Both radio components show structure in a Very Long Baseline Array (VLBA) 8.4-GHz radio image. No further extended structure is seen in Very Large Array (VLA), Multi-Element Radio Linked Interferometer Network (MERLIN) or VLBA images. Hubble Space Telescope (HST) WFPC2 images in F555W and F814W show two extended objects close to the radio components, which we identify as two lens galaxies. Their colours and mass-to-light ratios seem to favour two late-type spiral galaxies at relatively high redshifts (z_d ≥ 0.5). Faint emission is also detected at positions corresponding to the radio images. A two-lens mass model can explain the observed VLBA structure. The best-fitting model has a reduced χ^2 of 1.1. The relative positions of the VLBA subcomponents are reproduced within 0.08 mas, and the flux density ratios within 20 per cent. We also reproduce the position angle and separation of the two VLBA subcomponents in A and B within the observational errors, which we consider strong evidence for the validity of the lens model. Moreover, we find a surface density axis ratio of 0.74^(+0.10)_(0.12) for the primary lens (G1), consistent with the surface brightness axis ratio of 0.69 ± 0.15. Also, the surface density position angle of (4.9^(+28.2)_(-22.4)° of G1 compares well with the (−6±13) position angle of the surface brightness distribution. The errors indicate the 99 per cent confidence interval.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Koopmans, L. V. E.0000-0003-1840-0312
Blandford, R. D.0000-0002-1854-5506
Fassnacht, C. D.0000-0002-4030-5461
Pearson, T. J.0000-0001-5213-6231
Readhead, A. C. S.0000-0001-9152-961X
Additional Information:© 1999 RAS. Accepted 1998 October 19. Received 1998 October 16; in original form 1998 February 12. LVEK and AGdeB acknowledge support from an NWO program subsidy (grant number 781-76-101). This research was supported in part by the European Commission, TMR Programme, Research Network Contract ERBFMRXCT96-0034 'CERES'. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. MERLIN is a national UK facility operated by the University of Manchester on behalf of PPARC. This research used observations with the Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by Associated Universities for Research in Astronomy Inc. under NASA contract NAS5-26555. The Westerbork Synthesis Radio Telescope (WSRT) is operated by the Netherlands Foundation for Research in Astronomy (ASTRON) with the financial support from the Netherlands Organization for Scientific Research (NWO).
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)781-76-101
Marie Curie FellowshipERBFMRXCT96-0034
Particle Physics and Astronomy Research Council (PPARC)UNSPECIFIED
Subject Keywords:gravitational lensing
Issue or Number:4
Record Number:CaltechAUTHORS:20190523-125438341
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Official Citation:L. V. E. Koopmans, A. G. de Bruyn, D. R. Marlow, N. Jackson, R. D. Blandford, I. W. A. Browne, C. D. Fassnacht, S. T. Myers, T. J. Pearson, A. C. S. Readhead, P. N. Wilkinson, D. Womble, A new radio double lens from CLASS: B1127+385, Monthly Notices of the Royal Astronomical Society, Volume 303, Issue 4, 11 March 1999, Pages 727–735,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95750
Deposited By: George Porter
Deposited On:24 May 2019 14:22
Last Modified:19 Jan 2023 17:08

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