Velocity Dispersion of the Gravitational Lens 0957+561

Abstract

0957+561 is the first gravitational lens system to be discovered and first for which a time delay was measured. Because the system is unusually rich in observables such as image positions, fluxes, VLBI structure, and polarization it has been modelled quite extensively. However, since it resides in a cluster providing substantial convergence, the velocity dispersion of the lensing galaxy is an important component to models. We have measured this dispersion to be 288+/-9 kms (1-sigma), which implies a Hubble constant of 72+/-7 kms/Mpc (1-sigma) according to the preferred FGS model of Grogin and Narayan, and 70+/-7 kms/Mpc (1-sigma) using the SPLS model. The unknown velocity dispersion anisotropy of the central galaxy produces an additional uncertainty of perhaps 15% or more. We see no variation in dispersion with position to a radius of +/-3". In addition to a galaxy from the background cluster at z=0.5, our slit serendiptously picked up a galaxy at z = 0.448, and two galaxies which may be part of a background cluster at a redshift of z=0.91.

13 pages, AASTeX Latex, including 5 Postscript figures, submitted to Astrophysical Journal, June 25, 1998

References in corpus (6)

• Redshifts of the Gravitational Lenses B1422+231 and PG1115+080
• Measurements of the Sunyaev-Zeldovich Effect in the Nearby Clusters A478, A2142 and A2256
• The Tully-Fisher Relation and H_not
• An estimate of H_0 from Keck spectroscopy of the gravitational lens system 0957+561
• The Far Field Hubble Constant
• Improved Parameters and New Lensed Features for Q0957+561 from WFPC2 Imaging

Cited by in corpus (21)

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• A determination of H_0 with the CLASS gravitational lens B1608+656: II. Mass models and the Hubble constant from lensing
• The Host Galaxy of the Lensed Quasar Q 0957+561
• Improved Constraints on the Gravitational Lens Q0957+561. II. Strong Lensing
• Constraining the Cosmological Parameters using Strong Lensing
• Constraints on H_0 from the Central Velocity Dispersions of Lens Galaxies
• The Fundamental Plane and the evolution of the M/L ratio of early-type field galaxies up to z~1
• Values of H_0 from Models of the Gravitational Lens 0957+561
• The Hubble Constant and the Expansion Age of the Universe
• Constraining H0 from Chandra Observations of Q0957+561
• A reassessment of the data and models of the gravitational lens Q0957+561
• A New Microlensing Event in the Doubly-Imaged Quasar Q0957+561
• Applying MOG to lensing: Einstein rings, Abell 520 and the Bullet Cluster
• New Modeling of the Lensing Galaxy and Cluster of Q0957+561: Implications for the Global Value of the Hubble Constant
• Revealing the structure of the lensed quasar Q 0957+561: I. Accretion disk size
• Can Strong Gravitational Lensing Constrain Dark Energy?
• The coevolution of the velocity and mass functions of galaxies and dark haloes
• A Lensing View On The Fundamental Plane
• Spectroscopy of the Lens Galaxy of Q0957+561A,B. Implications of a possible central massive dark object