The DiskMass Survey Bershady Verheijen Westfall Martinsson Swaters

The Disk-Mass Survey Bershady Verheijen Westfall Martinsson Swaters Andersen goals: - obtain radial surface-density profiles Σ(r) of galaxy disks - determine M/L of stellar populations in disks - break disk-halo degeneracy in rotation curve decompositions - get ρDM(r) method: measure vertical stellar velocity dispersion σz data: R≈10 4 spectroscopy of Mg. Ib & Ca. II at ≤ 3 Rdisk (μB =24. 5) two custom-built wide-field fiber-based IFUs (Sparse. Pak, P-Pak) sample: ∼ 40 nearly face-on (incl=25°- 35°), kinematically regular spirals range in morphology, mass, color, surface brightness, SF rate. . . 1

Sparse. Pak P-Pak UW - Madison 3. 6 m WIYN, Kitt Peak 71"x 72" field of view 82 fibers (4. 7" ∅) 75 science, 7 sky R≈10. 000 (Hα, Mg. Ib, Ca. II) AIP - Potsdam 3. 5 m CAHA, Calar Alto 64"x 74" field of view 382 fibers (2. 7" ∅) 331 science, 36 sky, 15 calib. R≈8. 000 (Mg. Ib, Hα/Hβ/Hγ) 2

IFU spectroscopy : azimuthal averaging to gain S/N UGC 6918 HST/WFPC-2 P-Pak : Mg. Ib Sparse. Pak : Hα (3 -point dither) Mg. Ib, Ca. II 3

optical (SDSS) Sample & Strategy type, size, inclination, visually inspected non-interacting, non-barred 50 kpc • 400 galaxies pre-selected from UGC Hα velocity fields (Sparse. Pak) • Hα velocity fields of 130 randomly chosen spirals - regular Hα velocity fields - stellar kinematics (Mg. Ib, Ca. II) - optical imaging (U, B, V, R, I) - near-IR imaging (J, H, K) - Spitzer imaging (4. 5, 8, 24, 70μm) - HI & 1. 4 GHz continuum (ongoing) 2 arcmin • Subsample of 40 spirals with 8 micron (Spitzer) 2 arcmin 4

photometry Hα velocity field stellar VF & LOSVD U 6918 5

Ongoing work & some results U 6918 U 463 U 1635 Important (and time-consuming) issues: Registration: refine the pointings of the dithered Hα velocity field observations Ø Flexure issues (shifts, scale differences & rotations) Ø Decompose vel. disp ellipsiod (σr, σφ, σz) Westfall et al (astro-ph/0801. 4912) Ø Careful error propagation and understanding the error budget Ø 6

7

8