The relative contribution of baryons and dark matter to the inner regions of spiral galaxies provides critical clues to their formation and evolution , but it is generally difficult to determine .
For spiral galaxies that are strong gravitational lenses , however , the combination of lensing and kinematic observations can be used to break the disk-halo degeneracy .
In turn , such data constrain fundamental parameters such as i ) the mass density profile slope and axis ratio of the dark matter halo , and by comparison with dark matter-only numerical simulations the modifications imposed by baryons ; ii ) the mass in stars and therefore the overall star formation efficiency , and the amount of feedback ; iii ) by comparison with stellar population synthesis models , the normalization of the stellar initial mass function .
In this first paper of a series , we present a sample of 16 secure , 1 probable , and 6 possible strong lensing spiral galaxies , for which multi-band high-resolution images and rotation curves were obtained using the Hubble Space Telescope and Keck-II Telescope as part of the Sloan WFC Edge-on Late-type Lens Survey ( SWELLS ) .
The sample includes 8 newly discovered secure systems .
We characterize the sample of deflector galaxies in terms of their morphologies , structural parameters , and stellar masses .
We find that the SWELLS sample of secure lenses spans a broad range of morphologies ( from lenticular to late-type spiral ) , spectral types ( quantified by H \alpha emission ) , and bulge to total stellar mass ratio ( 0.22-0.85 ) , while being limited to M _ { * } > 10 ^ { 10.5 } M _ { \odot } .
The SWELLS sample is thus well-suited for exploring the relationship between dark and luminous matter in a broad range of galaxies .
We find that the deflector galaxies obey the same size-mass relation as that of a comparison sample of elongated non-lens galaxies selected from the SDSS survey .
We conclude that the SWELLS sample is consistent with being representative of the overall population of high-mass high-inclination disky galaxies .