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1608+656: A Gravitationally Lensed PostStarburst Radio Galaxy

Fassnacht, C. D. and Womble, D. S. and Neugebauer, G. and Browne, I. W. A. and Readhead, A. C. S. and Matthews, K. and Pearson, T. J. (1996) 1608+656: A Gravitationally Lensed PostStarburst Radio Galaxy. Astrophysical Journal, 460 (2). L103-L106. ISSN 0004-637X. doi:10.1086/309984.

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The gravitational lens system 1608+656 displays four flat-spectrum, pointlike components that are the images of the unresolved core of a double-lobed radio source. The lensing mass is a galaxy at z = 0.630. New spectra of this system enable us to determine a conclusive redshift of 1.394 for the lensed object. The spectra show prominent high-order Balmer absorption lines and Mg II absorption. These lines, and the absence of [O II] emission, indicate that this is a poststarburst or E + A galaxy. It is unique among lensed objects in not being a quasar and among E + A galaxies in having the highest known redshift. Even allowing for lens magnification, the lensed object is a very luminous galaxy, with an absolute magnitude, M(r) = -22.8 mag. The deconvolved infrared image indicates that the galaxy may be slightly resolved. The radio luminosity density of the lobes is L_(1.4) = 5.78 × 10^(25) W Hz^(-1), which puts the source on the boundary between FR I and FR II radio galaxies. Together with the redshift for the lens and a satisfactory mass model, the determination of the lensed object redshift makes this system an excellent candidate for measuring H_0.

Item Type:Article
Related URLs:
URLURL TypeDescription
Fassnacht, C. D.0000-0002-4030-5461
Readhead, A. C. S.0000-0001-9152-961X
Pearson, T. J.0000-0001-5213-6231
Additional Information:© The American Astronomical Society. Received 5 December 1995; accepted 17 January 1996. For valuable discussions, we thank Roger Blandford, David Hogg, Steve Myers, Ann Zabludoff, Neal Jackson, and Lee Armus. We are grateful to Greg Taylor for helping with the optical observations. We thank the staff at Palomar Observatory for their assistance during our observing runs. CLASS and Infrared astrophysics at Caltech are supported by grants from the NSF. C. D. F. is supported by a NSF Graduate Research Fellowship. D. S. W. acknowledges support of a Hubble Fellowship provided by NASA through grant HF-1040.01-92A from the STScl, which is operated by AURA.
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
NASA Hubble FellowshipHF-1040.01-92A
Subject Keywords:Gravitational lensing
Issue or Number:2
Record Number:CaltechAUTHORS:20170213-111408479
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:74239
Deposited By: Melissa Ray
Deposited On:13 Feb 2017 22:30
Last Modified:11 Nov 2021 05:25

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