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The Quadruple Gravitational Lens PG 1115+080: Time Delays and Models

Paul L. SchechterDepartment of Physics, Massachusetts Institute of Technology, Cambridge, MA 02138C. D. BailynDepartment of Astronomy, Yale University, New Haven, CT 06520-8101Robert C. BarrRichard BarvainisMIT Haystack Observatory, Westford, MA 01886C. M. BeckerDepartment of Physics, Massachusetts Institute of Technology, Cambridge, MA 02138G. M. BernsteinDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109John P. BlakesleeDepartment of Physics, Massachusetts Institute of Technology, Cambridge, MA 02138S. J. BusDepartment of Earth Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139Alan DresslerCarnegie Observatories, Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101E. FalcoHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138Robert A. FesenDepartment of Physics and Astronomy, Dartmouth College, Hanover, NH 03755-3528Phillipe FischerDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109Karl GebhardtDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109Dianne HarmerNational Optical Astronomy Observatories, P.O. Box 26732, Tucson, AZ 85726Jacqueline N. HewittDepartment of Physics, Massachusetts Institute of Technology, Cambridge, MA 02138J. HjorthInstitute of Astronomy, Madingly Road, Cambridge CB3 0HA, EnglandTodd HurtDepartment of Physics, University of California, Santa Barbara, CA 93106A. O. JaunsenNordic Optical Telescope, E-38700 Canarias, SpainMario MateoDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109Doerte MehlertD. O. RichstoneDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109Linda S. SparkeWashburn Observatory, University of Wisconsin, Madison, WI 53706J. R. ThorstensenDepartment of Physics and Astronomy, Dartmouth College, Hanover, NH 03755-3528J. TonryDepartment of Physics, Massachusetts Institute of Technology, Cambridge, MA 02138G. WegnerDepartment of Physics and Astronomy, Dartmouth College, Hanover, NH 03755-3528Daryl W. WillmarthNational Optical Astronomy Observatories, P.O. Box 26732, Tucson, AZ 85726Guy WortheyDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109

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Annotatsiya

Optical photometry is presented for the quadruple gravitational lens PG1115+080. A preliminary reduction of data taken from November 1995 to June 1996 gives component ``C'' leading component ``B'' by 23.7+/-3.4 days and components ``A1'' and ``A2'' by 9.4 days. A range of models has been fit to the image positions, none of which gives an adequate fit. The best fitting and most physically plausible of these, taking the lensing galaxy and the associated group of galaxies to be singular isothermal spheres, gives a Hubble constant of 42 km/s/Mpc for Omega=1, with an observational uncertainty of 14%, as computed from the B-C time delay measurement. Taking the lensing galaxy to have an approximately E5 isothermal mass distribution yields H0=64 km/sec/Mpc while taking the galaxy to be a point mass gives H0=84 km/sec/Mpc. The former gives a particularly bad fit to the position of the lensing galaxy, while the latter is inconsistent with measurements of nearby galaxy rotation curves. Constraints on these and other possible models are expected to improve with planned HST observations.

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DOI: 10.1086/310478

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