The GALEX Arecibo SDSS Survey. IV. Baryonic Mass-Velocity-Size Relations
  of Massive Galaxies
  We present dynamical scaling relations for a homogeneous and representative
sample of ~500 massive galaxies, selected only by stellar mass (>10^10 Msun)
and redshift (0.025<z<0.05) as part of the ongoing GALEX Arecibo SDSS Survey.
We compare baryonic Tully-Fisher (BTF) and Faber-Jackson (BFJ) relations for
this sample, and investigate how galaxies scatter around the best fits obtained
for pruned subsets of disk-dominated and bulge-dominated systems. The BFJ
relation is significantly less scattered than the BTF when the relations are
applied to their maximum samples, and is not affected by the inclination
problems that plague the BTF. Disk-dominated, gas-rich galaxies systematically
deviate from the BFJ relation defined by the spheroids. We demonstrate that by
applying a simple correction to the stellar velocity dispersions that depends
only on the concentration index of the galaxy, we are able to bring disks and
spheroids onto the same dynamical relation -- in other words, we obtain a
generalized BFJ relation that holds for all the galaxies in our sample,
regardless of morphology, inclination or gas content, and has a scatter smaller
than 0.1 dex. We find that disks and spheroids are offset in the stellar
dispersion-size relation, and that the offset is removed when corrected
dispersions are used instead. The generalized BFJ relation represents a
fundamental correlation between the global dark matter and baryonic content of
galaxies, which is obeyed by all (massive) systems regardless of morphology.
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