Mass and dust in the disk of a spiral lens galaxy
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Date
2003
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Abstract
Gravitational lensing is a potentially important probe of spiral galaxy structure, but only a few cases of lensing by spiral galaxies are known. We present Hubble Space Telescope and Magellan observations of the two-image quasar PMN J2004-1349, revealing that the lens galaxy is a spiral galaxy. One of the quasar images passes through a spiral arm of the galaxy and suffers 3 mag of V-band extinction. Using simple lens models, we show that the mass quadrupole is well aligned with the observed galaxy disk. A more detailed model with components representing the bulge and disk gives a bulge-to-disk mass ratio of 0.16+/-0.05. The addition of a spherical dark halo, tailored to produce an overall. at rotation curve, does not change this conclusion.
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dark matter, dust, extinction, galaxies : spiral, structure, halos gravitational lensing, quasars : individual (PMN J2004-1349)