Is there a fundamental line for disk galaxies?

Joshua D. Simon, Francisco Prada, José M. Vílchez, Leo Blitz, Brant Robertson

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We show that there are strong local correlations between metallicity, surface brightness, and dynamical mass-to-light ratio with M33, analogous to the fundamental line of dwarf galaxies identified by Prada & Burkert. Using nearinfrared imaging from 2MASS, the published rotation curve of M33, and literature measurements of the metallicities of H II regions and supergiant stars, we demonstrate that these correlations hold for points at radial distances between 140 pc and 6.2 kpc from the center of the galaxy. At a given metallicity or surface brightness, M33 has a mass-to-light ratio approximately 4 times as large as the Local Group dwarf galaxies; other than this constant offset, we see broad agreement between the M33 and dwarf galaxy data. We use analytical arguments to show that at least two of the three fundamental line correlations are basic properties of disk galaxies that can be derived from very general assumptions. We investigate the effect of supernova feedback on the fundamental line with numerical models and conclude that while feedback clearly controls the scatter in the fundamental line, it is not needed to create the fundamental line itself, in agreement with our analytical calculations. We also compare the M33 data with measurements of a simulated disk galaxy, finding that the simulation reproduces the trends in the data correctly and matches the fundamental line, although the metallicity of the simulated galaxy is too high, and the surface brightness is lower than that of M33.

Original languageEnglish (US)
Pages (from-to)709-721
Number of pages13
JournalAstrophysical Journal
Issue number2 I
StatePublished - Oct 1 2006


  • Galaxies: abundances
  • Galaxies: formation
  • Galaxies: fundamental parameters
  • Galaxies: individual (M33)
  • Galaxies: kinematics and dynamics
  • Galaxies: spiral

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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