Rotation Curve Anomaly and Galactic Warp in M51

Abstract

We revisit the anomaly of rotation curve in the nearly face-on galaxy M51 that shows an apparently faster decrease of rotation velocity than the Keplerian law in the outer disk, further showing apparent counter rotation in the outermost HI disk. We interpret this anomaly as due to warping of the galactic disk, and determined the warping structure of M51's disk using the tilted-ring method, assuming that the intrinsic rotation curve is normal. It is shown that the disk is nearly flat in the inner disk at a constant inclination angle, but the disk suddenly bends at radius 7.5 kpc by about 27$°$. The inclination angle, then, decreases monotonically outward reaching a perfect face-on ring at 18 kpc, beyond which the disk is warped in the opposite sense to the inner disk, resulting in apparent counter rotation.

arXiv comment5 papge, 7 figures, accepted for PASJ

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Cited by in corpus (11)

• Simulations of the star-forming molecular gas in an interacting M51-like galaxy
• Rotation and Mass in the Milky Way and Spiral Galaxies
• Dynamical Characterization of Galaxies at z~4-6 via Tilted Ring Fitting to ALMA [CII] Observations
• Slicing the cool circumgalactic medium along the major-axis of a star-forming galaxy at $z=0.7$
• Total eclipse of the heart: The AM CVn Gaia14aae / ASSASN-14cn
• Instability analysis for spiral arms of local galaxies: M51, NGC3627 and NGC628
• Searching for Milky Way twins: Radial abundance distribution as a strict criterion
• A SOFIA Survey of [CII] in the galaxy M51 II. [CII] and CO kinematics across spiral arms
• FEASTS Combined with Interferometry. III. The Low Column Density HI Around M51 and Possibility of Turbulent-mixing Gas Accretion
• Mapping non-axisymmetric velocity fields of external galaxies
• The young stellar clusters in M51 and the impact of GMC encounters