We present mass models of a sample of 14 spiral and 14 S0 galaxies that constrain their stellar and dark matter content .
For each galaxy we derive the stellar mass distribution from near-infrared photometry under the assumptions of axisymmetry and a constant K _ { S } -band stellar mass-to-light ratio , ( M / L ) _ { K _ { S } } .
To this we add a dark halo assumed to follow a spherically symmetric Navarro , Frenk & White ( NFW ) profile and a correlation between concentration and dark mass within the virial radius , M _ { DM } .
We solve the Jeans equations for the corresponding potential under the assumption of constant anisotropy in the meridional plane , \beta _ { z } .
By comparing the predicted second velocity moment to observed long-slit stellar kinematics , we determine the three best-fitting parameters of the model : ( M / L ) _ { K _ { S } } , M _ { DM } and \beta _ { z } .
These simple axisymmetric Jeans models are able to accurately reproduce the wide range of observed stellar kinematics , which typically extend to \approx 2–3 R _ { \mathrm { e } } or , equivalently , \approx 0.5–1 R _ { 25 } .
We find a median stellar mass-to-light ratio at K _ { S } -band of 1.09 ( M / L ) _ { K _ { S } , \odot } with an rms scatter of 0.31 .
We present preliminary comparisons between this large sample of dynamically determined stellar mass-to-light ratios and the predictions of stellar population models .
The stellar population models predict slightly lower mass-to-light ratios than we measure .
The mass models contain a median of 15 per cent dark matter by mass within an effective radius R _ { \mathrm { e } } ( defined here as the semi-major axis of the ellipse containing half the K _ { S } -band light ) , and 49 per cent within the optical radius R _ { 25 } .
Dark and stellar matter contribute equally to the mass within a sphere of radius 4.1 \hbox { $R _ { \mathrm { e } } $ } or 1.0 R _ { 25 } .
There is no evidence of any significant difference in the dark matter content of the spirals and S0s in our sample .
Although our sample contains barred galaxies , we argue a posteriori that the assumption of axisymmetry does not significantly affect our results .
Models without dark matter are also able to satisfactorily reproduce the observed kinematics in most cases .
The improvement when a halo is added is statistically significant , however , and the stellar mass-to-light ratios of mass models with dark haloes match the independent expectations of stellar population models better .