The Link Between SCUBA and Spitzer: Cold Galaxies at z<1
  We show that the far-IR properties of distant Luminous and Ultraluminous
InfraRed Galaxies (LIRGs and ULIRGs) are on average divergent from analogous
sources in the local Universe. Our analysis is based on Spitzer MIPS and IRAC
data of L_IR>10^10 L_solar, 70um-selected objects in the 0.1<z<2 redshift range
and supported by a comparison with the IRAS Bright Galaxy Sample. The majority
of the objects in our sample are described by Spectral Energy Distributions
(SEDs) which peak at longer wavelengths than local sources of equivalent total
infrared luminosity. This shift in SED peak wavelength implies a noticeable
change in the dust and/or star-forming properties from z~0 to the early
Universe, tending towards lower dust temperatures, indicative of strong
evolution in the cold dust, `cirrus', component. We show that these objects are
potentially the missing link between the well-studied local IR-luminous
galaxies, Spitzer IR populations and SCUBA sources -- the z<1 counterparts of
the cold z>1 SubMillimetre Galaxies (SMGs) discovered in blank-field
submillimetre surveys. The Herschel Space Observatory is well placed to fully
characterise the nature of these objects, as its coverage extends over a major
part of the far-IR/submm SED for a wide redshift range.
