A Dynamical Model of the M101 / NGC 5474 Encounter

Abstract

We present the first dynamical simulation that recreates the major properties of the archetypal nearby spiral galaxy M101. Our model describes a grazing but relatively close (14 kpc) passage of the companion galaxy NGC 5474 through M101's outer disk approximately 200 Myr ago. The passage is retrograde for both disks, which yields a relatively strong gravitational response while suppressing the formation of long tidal tails. The simulation reproduces M101's overall lopsidedness, as well as the extended NE Plume and sharp western edge of the galaxy's disk. The post-starburst populations observed in M101's NE Plume are likely a result of star formation triggered at the point of contact where the galaxies collided. Over time, this material will mix azimuthally, leaving behind diffuse, kinematically coherent stellar streams in M101's outer disk. At late times after the encounter, the density profile of M101's disk shows a broken "upbending" profile similar to those seen in spiral galaxies in denser environments, further demonstrating the connection between interactions and long-term structural changes in galaxy disks.

arXiv comment8 pages, 4 figures, accepted for publication in the Astrophysical Journal (Letters). Updated to (mostly) match the published version. Additional animations and simulation data are available at http://astroweb.case.edu/hos/M101Sim/

References in corpus (13)

• THINGS: The HI Nearby Galaxy Survey
• The structure of galactic disks: Studying late-type spiral galaxies using SDSS
• Bulgeless Giant Galaxies Challenge our Picture of Galaxy Formation by Hierarchical Clustering
• Anti-Truncation of Disks in Early-Type Barred Galaxies
• Starbursts triggered by inter-galactic tides and interstellar compressive turbulence
• Fully compressive tides in galaxy mergers
• The Extended Optical Disk of M101
• The HI environment of the M101 group
• Ultraviolet Signatures of Tidal Interaction in the Giant Spiral Galaxy, M101
• Morphology and enhanced star formation in a Cartwheel-like ring galaxy
• On the varied origins of up-bending breaks in galaxy disks
• Stellar Populations in the Outer Disk and Halo of the Spiral Galaxy M101
• An off-centred bulge or a satellite? Hydrodynamical $N$-body simulations of the disc galaxy NGC 5474

Cited by in corpus (1)

• Deep Narrowband Photometry of the M101 Group: Strong-Line Abundances of 720 HII Regions