Properties of Galaxies in the Disc Central Surface Brightness Gap
  Intermediate surface brightness (ISB) galaxies are less numerous than their
counterparts at high and low surface brightness (HSB and LSB). Investigating
ISB characteristics from a sample from the S4G survey, complete down to
M_B=-16, we find that they have intermediate stellar, gas and baryonic masses
and on average as much gas as stars. They lie on the (baryonic) Tully-Fisher
relation between HSBs and LSBs, although they present a higher scatter than the
latter. Their stellar to baryonic mass ratios have intermediate values unlike
their condensed baryonic fractions. By comparing their environments, as
classified by the eigenvalues of the velocity shear tensor of local constrained
simulations, ISBs have a 5-10% probability higher (smaller) to be in sheets
(filaments) with respect to HSBs and LSBs. Additionally, for galaxies in
filaments (with close neighbors), the mass and mu_0 are correlated at 2.5 (2)
sigma more than for those in sheets. ISBs live in regions where the divergence
of the velocity field is smaller than where HSBs and LSBs live, a result at
more than 50% significance. ISBs may exist as an unstable transition state
between LSBs and HSBs, the low flow activity environment maximally encouraging
their formation. Interaction events altering the central baryon fraction could
happen at a lower rate in these less dense environment, whilst in the higher
density environments the LSBs are primarily satellite galaxies, whose accretion
is sufficiently constrained that it fails to promote them to HSBs.
