Gravitationally lensed quasar 0957+561: VLA observations and mass models
The gravitationally lensed quasar 0957+561 has been studied at wavelengths of 2, 6, 18, and 21 cm, using the VLA. The A and B quasar images have essentially identical radio spectra but polarization rotation measures that differ by 100 rad m/sup -2/. The lambda = 6 cm maps are of especially high quality and show many more features than are visible optically. The giant cD galaxy designated G1 in the optical observations has a radio source at its nucleus, 1'' north of the B image, and designated G in the radio maps. In addition, there is a pronounced jet of relativistic plasma extending northeast of the A image, with a less pronounced lobe to the southwest. These have no obvious counterpart at the B image. All singularity-free gravitational lenses produce an odd number of images, leading to an interpretation in which most of the jet structures are singly imaged. A number of possible mass models were considered, one of which, by judicious choice of parameters, explains the radio observations acceptably. The cD galaxy is an important component of the lens, but an additional, far more massive component must be invoked. This must be nonluminous, generally associated with the cluster, but not with individual galaxies. The total mass is model-dependent, but the mass-to-luminosity ratio in the inner part of the system must be several thousand to one.
- Research Organization:
- Massachusets Institute of Technology; Bell Telephone Laboratories
- OSTI ID:
- 5223867
- Journal Information:
- Astrophys. J.; (United States), Vol. 293:2
- Country of Publication:
- United States
- Language:
- English
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