Spiral Density Waves in M81. I. Stellar Spiral Density Waves

Abstract

Aside from the grand-design stellar spirals appearing in the disk of M81, a pair of stellar spiral arms situated well inside the bright bulge of M81 has been recently discovered by Kendall et al. (2008). The seemingly unrelated pairs of spirals pose a challenge to the theory of spiral density waves. To address this problem, we have constructed a three component model for M81, including the contributions from a stellar disk, a bulge, and a dark matter halo subject to observational constraints. Given this basic state for M81, a modal approach is applied to search for the discrete unstable spiral modes that may provide an understanding for the existence of both spiral arms. It is found that the apparently separated inner and outer spirals can be interpreted as a single trailing spiral mode. In particular, these spirals share the same pattern speed 25.5 km s${}^{-1}$ kpc${}^{-1}$ with a corotation radius of 9.03 kpc. In addition to the good agreement between the calculated and the observed spiral pattern, the variation of the spiral amplitude can also be naturally reproduced.

25 pages, 6 figures, accepted for publication in ApJ

References in corpus (2)

• Virgo cluster early-type dwarf galaxies with the Sloan Digital Sky Survey. I. On the possible disk nature of bright early-type dwarfs
• Tracing spiral density waves in M81

Cited by in corpus (10)

• Non-linear violent disc instability with high Toomre's Q in high-redshift clumpy disc galaxies
• Bars and spirals in tidal interactions with an ensemble of galaxy mass models
• Spiral-arm instability: giant clump formation via fragmentation of a galactic spiral arm
• Testing Density Wave Theory with Resolved Stellar Populations around Spiral Arms in M81
• Feathering Instability of Spiral Arms. II. Parameter Study
• Spiral arms and disc stability in the Andromeda galaxy
• Multiwavelength Bulge-Disk Decomposition for the Galaxy M81 (NGC 3031). I. Morphology
• Global Spiral Density Wave Modes in Protoplanetary Disks: Morphology of Spiral Arms
• Spiral Density Waves in M81. II. Hydrodynamic Simulations for Gas Response to Stellar Spiral Density Waves
• Massive Star Clusters in the Semi-Analytical Galaxy Formation Model L-Galaxies 2020