Exponential Stellar Disks in Low Surface Brightness Galaxies: A Critical Test of Viscous Evolution

Abstract

Viscous redistribution of mass in Milky Way-type galactic disks is an appealing way of generating an exponential stellar profile over many scale lengths, almost independent of initial conditions, requiring only that the viscous timescale and star formation timescale are approximately equal. However, galaxies with solid-body rotation curves cannot undergo viscous evolution. Low surface brightness (LSB) galaxies have exponential surface brightness profiles, yet have slowly rising, nearly solid-body, rotation curves. Because of this, viscous evolution may be inefficient in LSB galaxies: the exponential profiles, instead would give important insight into initial conditions for galaxy disk formation. Using star formation laws from the literature, and tuning the efficiency of viscous processes to reproduce an exponential stellar profile in Milky Way-type galaxies, I test the role of viscous evolution in LSB galaxies. Under the conservative and not unreasonable condition that LSB galaxies are gravitationally unstable for at least a part of their lives, I find that it is impossible to rule out a significant role for viscous evolution. This type of model still offers an attractive way of producing exponential disks, even in LSB galaxies with slowly-rising rotation curves.

6 pages, 3 embedded figures. Astrophysical Journal, accepted

References in corpus (8)

• Stellar mass-to-light ratios and the Tully-Fisher relation
• H alpha rotation curves of Low Surface Brightness galaxies
• Molecular gas in late-type galaxies
• The Origin of the Density Distribution of Disk Galaxies: A New Problem for the Standard Model of Disk Formation
• The Evolution of Stellar Exponential Discs
• CO Detections of Edge-On Low Surface Brightness Galaxies
• High-Resolution Optical Rotation Curves of Low-Luminosity Spiral Galaxies
• Forming stars on a viscous timescale: the key to exponential stellar profiles in disk galaxies?

Cited by in corpus (9)

• On the Origin of Exponential Galaxy Disks
• The ACS Nearby Galaxy Survey Treasury I. The Star Formation History of the M81 Outer Disk
• A Dimensional study of Disk Galaxies
• Evolution along the sequence of S0 Hubble types induced by dry minor mergers. II - Bulge-disk coupling in the photometric relations through merger-induced internal secular evolution
• Optical Imaging and Spectroscopy of the Edge-On Sbc Galaxy UGC10043: Evidence for a Galactic Wind and a Peculiar Triaxial Bulge
• Bulge evolution in face-on spirals and low surface brightness galaxies
• The puzzle about the radial cut-off in galactic disks
• Effective viscosity from cloud-cloud collisions in three-dimensional global SPH simulations
• Cloud angular momentum and effective viscosity in global SPH simulations with feedback