THE PdBI ARCSECOND WHIRLPOOL SURVEY (PAWS): MULTI-PHASE COLD GAS KINEMATIC OF M51

The kinematic complexity and the favorable position of M51 on the sky make this galaxy an ideal target to test different theories of spiral arm dynamics. Using a tilted-ring analysis supported by several other archival data sets, we update the estimation of M51's position angle (P.A. = (173 + or - 3)[degrees]) and inclination (i = (22 + or - 5)[degrees]). Harmonic decomposition of the high-resolution (~40 pc) CO velocity field shows the first kinematic evidence of an m = 3 wave in the inner disk of M51 with a corotation at R sub(CR, )m=3 = 1.1 + or - 0.1 kpc and a pattern speed of [Omega] sub(p, m=3) approximately 140 km s super(-1) kpc super(-1). Our joint analysis of HI and CO velocity fields at low and high spatial resolution reveals that the atomic and molecular gas phases respond differently to the spiral perturbation due to their different vertical distribution and emission morphology.