Dark and baryonic matter in bright spiral galaxies. II. Radial distributions for 34 galaxies

Susan A. Kassin, Roelof S. De Jong, Benjamin J. Weiner

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


We decompose the rotation curves of 34 bright spiral galaxies into baryonic and dark matter components. Stellar mass profiles are created by applying color-M/L relations to near-infrared and optical photometry. We find that the radial profile of the baryonic-to-dark-matter ratio is self-similar for all galaxies, when scaled to the radius at which the contribution of the baryonic mass to the rotation curve equals that of the dark matter (RX). We argue that this is due to the quasi-exponential nature of disks and rotation curves that are nearly flat after an initial rise. The radius RX is found to correlate most strongly with baryonic rotation speed, such that galaxies with RX measurements that lie further out in their disks rotate faster. This quantity also correlates very strongly with stellar mass, Hubble type, and observed rotation speed; B-band central surface brightness is less related to RX than these other galaxy properties. Most of the galaxies in our sample appear to be close to maximal disk. For these galaxies, we find that maximum observed rotation speeds are tightly correlated with maximum rotation speeds predicted from the baryon distributions, such that one can create a Tully-Fisher relation based on surface photometry and redshifts alone. Finally, we compare our data to the NFW parameterization for dark matter profiles with and without including adiabatic contraction as it is most commonly implemented. Fits are generally poor, and all but two galaxies are better fit if adiabatic contraction is not performed. In order to have better fits, and especially to accommodate adiabatic contraction, baryons would need to contribute very little to the total mass in the inner parts of galaxies, seemingly in contrast with other observational constraints.

Original languageEnglish (US)
Pages (from-to)804-824
Number of pages21
JournalAstrophysical Journal
Issue number2 I
StatePublished - Jun 1 2006
Externally publishedYes


  • Galaxies: fundamental parameters
  • Galaxies: general
  • Galaxies: halos
  • Galaxies: kinematics and dynamics
  • Galaxies: spiral
  • Galaxies: stellar content

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Dark and baryonic matter in bright spiral galaxies. II. Radial distributions for 34 galaxies'. Together they form a unique fingerprint.

Cite this