Improving the triaxial bulge model of M31

Abstract

A detailed hydrodynamical model of the gas flow in the triaxial gravitational potential of the bulge of the Andromeda galaxy (M31) has recently been proposed by Berman (2001) astro-ph/0103209, and shown to provide excellent agreement with the CO emission line velocities observed along its major axis. In the present paper, we confirm the validity of that model by showing that it can also reproduce the CO velocities observed off the major axis - a much more robust test. The CO observations, however, tend to span a wider range of velocities than a direct application of the original model of Berman would suggest. This situation can be improved significantly if the molecular disk is made thicker, a requirement already encountered in dynamical simulations of other spiral galaxies, and typically attributed to a broadening of the molecular layer in galactic fountain-like processes. In the central regions of M31, however, it is unclear whether there actually is a thick molecular disk, or whether broadening the molecular layer is merely an artificial theoretical means of accounting for some disk warping. Other effects not included in the model, such as hydraulic jumps, might also contribute to a widening of the velocities.

6 pages, 3 figures, accepted for publication in MNRAS

References in corpus (4)

• The Milky Way in Molecular Clouds: A New Complete CO Survey
• Constraints from Dynamical Friction on the Dark Matter Content of Barred Galaxies
• The Formation of Molecular Clouds
• Hydrodynamic simulations of the triaxial bulge of M31

Cited by in corpus (14)

• A wide-field HI mosaic of Messier 31. II.The disk warp, rotation and the dark matter halo
• Molecular gas in the Andromeda galaxy
• Investigating the Andromeda Stream: I. Simple Analytic Bulge-Disk-Halo Model for M31
• Unveiling the Boxy Bulge and Bar of the Andromeda Spiral Galaxy
• Eccentric-disk models for the nucleus of M31
• M31's Undisturbed Thin Disk of Globular Clusters
• Sculpting Andromeda -- made-to-measure models for M31's bar and composite bulge: dynamics, stellar and dark matter mass
• Planetary Nebulae Kinematics in M31
• Self-Gravitating Eccentric Disk Models for the Double Nucleus of M31
• Andromeda chained to the Box -- Dynamical Models for M31: Bulge & Bar
• Evidence for non-axisymmetry in M31 from wide-field kinematics of stars and gas
• Large-scale Hydrodynamical Shocks as the Smoking Gun Evidence for a Bar in M31
• The Complex Structure of the Bulge of M31
• Molecular Gas in Spiral Galaxies