GAMA/H-ATLAS: Linking the Properties of Sub-mm Detected and Undetected
  Early-Type Galaxies: I. z$\le$0.06 Sample
  We present two large, nearby (0.013$\le$z$\le$0.06) samples of Early-Type
Galaxies (ETGs): a visually classified sample of 220 ETGs, created using
source-matched data from the Galaxy and Mass Assembly (GAMA) database with
FIR/sub-mm detections from $Herschel$-ATLAS; and a visually classified sample
of 551 ETGs which are undetected with $Herschel$-ATLAS. Active galactic nuclei
(AGN) are removed from our samples using optical emission line diagnostics.
These samples are scrutinised to determine characteristics of sub-mm detected
versus undetected ETGs. We find similarities in the stellar mass distributions
of the two ETG samples but testing other properties uncovers significant
differences. The sub-mm detected sample is shown to have lower concentration
and S\'ersic indices than those in the undetected sample - a result which may
be linked to the presence of dust in the former. Optical and UV-optical colours
are also shown to be much bluer, indicating that the dust is linked with recent
star formation. The intrinsic effective radii are on average 1.5 times larger
for the sub-mm detected ETGs. Surface densities and groups data from the GAMA
database are examined for the two samples, leading to the conclusion that dusty
ETGs inhabit sparser environments than non-dusty ETGs in the nearby universe,
although environments of the brightest ETGs are shown to differ the least.
Modified Planck functions are fit to the H-ATLAS detected PACS and SPIRE fluxes
for ETGs with sub-mm flux densities of at least 3$\sigma$ in the 350$\mu$m
SPIRE band, giving a resultant mean cold dust temperature of T$_{d}$=22.1K,
with a range of 9-30K. The corresponding mean dust mass is
1.8$\times10^{7}$M$_{\odot}$, with a range of
(0.08-35.0)$\times10^{7}$M$_{\odot}$. The dust masses calculated from these
fits, normalised by stellar mass, are shown to increase with decreasing stellar
mass and bluer colours.
