The kinematics of the barred spiral galaxy NGC 3059

Stellar and Hβ emission line radial velocities and stellar velocity dispersion measurements of the bar of the face-on SBc spiral galaxy NGC 3059 are presented. Along the major axis of the bar the radial velocities are constant, but going in a direction perpendicular to the bar from one side to the other, there is a substantial velocity increment of 70 km s^-1^. Assuming that the systematic motions are confined to the plane of the galaxy, this jump can be explained by a stellar streaming of about 100 km s^-1^ along the bar, as predicted by numerical studies. The emission line radial velocities generally follow the stellar velocities with some small scale deviations. The stellar velocity dispersion is essentially constant at a level of 53 km s^-1^ in the bar, and drops steeply outside. Comparison with z-direction bar dispersions of other galaxies shows that this value is considerably lower than the average value of ~140 km s^-1^ for SB0 galaxy bars.<br/

A Face-On Tully-Fisher Relation

We construct the first "face-on" Tully-Fisher (TF) relation for 24 galaxies with inclinations between 16 degrees and 41 degrees. The enabling measurements are integral-field, echelle spectroscopy from the WIYN 3.5m telescope, which yield accurate kinematic estimates of disk inclination to 15 degrees. Kinematic inclinations are of sufficient accuracy that our measured TF scatter of 0.42 mag is comparable to other surveys even without internal-absorption corrections. Three of four galaxies with significant kinematic and photometric asymmetries also have the largest deviations from our TF relation, suggesting that asymmetries make an important contribution to TF scatter. By measuring inclinations below 40 degrees, we establish a direct path to linking this scatter to the unprojected structure of disks and making non-degenerate dynamical mass-decompositions of spiral galaxies.Comment: 13 pages, 3 figures (2 color). Accepted for publication in ApJ Letter

The Balance of Dark and Luminous Mass in Rotating Galaxies

A fine balance between dark and baryonic mass is observed in spiral galaxies. As the contribution of the baryons to the total rotation velocity increases, the contribution of the dark matter decreases by a compensating amount. This poses a fine-tuning problem for \LCDM galaxy formation models, and may point to new physics for dark matter particles or even a modification of gravity.Comment: 4 pages RevTeX. Phys. Rev. Letters, in pres