We determine the mass distribution of a spiral galaxy, 2237+0305, using both gravitational lensing and dynamical constraints. We find that lensing can break the disc-halo degeneracy. 2237+0305 has a submaximal disc, contributing 57 +/- 3 per cent of the rotational support at the disc maximum. The disc mass-to-light ratio is 1.1 +/- 0.2 in the I band and the bulge, 2.9 +/- 0.5. The dark matter halo, modelled as a softened isothermal sphere, has a large core radius (13.4 +/- 0.4 kpc ≡ 1.4rd) to high accuracy for the best-fitting solution. The image positions are reasonably well fitted, but require further rotation information to obtain a unique solution.
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2002
- gravitational lensing;
- galaxies: kinematics and dynamics;
- dark matter;
- 11 pages, 6 figures, accepted by MNRAS, in press