The Galaxy End Sequence
  A common assumption is that galaxies fall in two distinct regions on a plot
of specific star-formation rate (SSFR) versus galaxy stellar mass: a
star-forming Galaxy Main Sequence (GMS) and a separate region of `passive' or
`red and dead galaxies'. Starting from a volume-limited sample of nearby
galaxies designed to contain most of the stellar mass in this volume, and thus
being a fair representation of the Universe at the end of 12 billion years of
galaxy evolution, we investigate the distribution of galaxies in this diagram
today. We show that galaxies follow a strongly curved extended GMS with a steep
negative slope at high galaxy stellar masses. There is a gradual change in the
morphologies of the galaxies along this distribution, but there is no clear
break between early-type and late-type galaxies. Examining the other evidence
that there are two distinct populations, we argue that the `red sequence' is
the result of the colours of galaxies changing very little below a critical
value of the SSFR, rather than implying a distinct population of galaxies, and
that Herschel observations, which show at least half of early-type galaxies
contain a cool interstellar medium, also imply continuity between early-type
and late-type galaxies. This picture of a unitary population of galaxies
requires more gradual evolutionary processes than the rapid quenching processes
needed to to explain two distinct populations. We challenge theorists to
reproduce the properties of this `Galaxy End Sequence'.
