H-ATLAS/GAMA : The nature and characteristics of optically red galaxies detected at submillimetre wavelengths
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Author
Dariush, A.
Dib, S.
Hony, S.
Smith, D. J. B.
Zhukovska, S.
Dunne, L.
Eales, S.
Andrae, E.
Baes, M.
Baldry, I.
Bauer, A.
Bland-Hawthorn, J.
Brough, S.
Bourne, N.
Cava, A.
Clements, D.
Cluver, M.
Cooray, A.
Zotti, G. De
Driver, S.
Grootes, M. W.
Hopkins, A. M.
Hopwood, R.
Kaviraj, S.
Kelvin, L.
Lara-Lopez, M. A.
Liske, J.
Loveday, J.
Maddox, S.
Madore, B.
Michalowski, M. J.
Pearson, C.
Popescu, C.
Robotham, A.
Rowlands, K.
Seibert, M.
Shabani, F.
Smith, M. W. L.
Taylor, E. N.
Tuffs, R.
Valiante, E.
Virdee, J. S.
Attention
2299/18844
Abstract
We combine Herschel/SPIRE sub-millimeter (submm) observations with existing multi-wavelength data to investigate the characteristics of low redshift, optically red galaxies detected in submm bands. We select a sample of galaxies in the redshift range 0.01$\leq$z$\leq$0.2, having >5$\sigma$ detections in the SPIRE 250 micron submm waveband. Sources are then divided into two sub-samples of $red$ and $blue$ galaxies, based on their UV-optical colours. Galaxies in the $red$ sample account for $\approx$4.2 per cent of the total number of sources with stellar masses M$_{*}\gtrsim$10$^{10}$ Solar-mass. Following visual classification of the $red$ galaxies, we find that $\gtrsim$30 per cent of them are early-type galaxies and $\gtrsim$40 per cent are spirals. The colour of the $red$-spiral galaxies could be the result of their highly inclined orientation and/or a strong contribution of the old stellar population. It is found that irrespective of their morphological types, $red$ and $blue$ sources occupy environments with more or less similar densities (i.e., the $\Sigma_5$ parameter). From the analysis of the spectral energy distributions (SEDs) of galaxies in our samples based on MAGPHYS, we find that galaxies in the $red$ sample (of any morphological type) have dust masses similar to those in the $blue$ sample (i.e. normal spiral/star-forming systems). However, in comparison to the $red$-spirals and in particular $blue$ systems, $red$-ellipticals have lower mean dust-to-stellar mass ratios. Besides galaxies in the $red$-elliptical sample have much lower mean star-formation/specific-star-formation rates in contrast to their counterparts in the $blue$ sample. Our results support a scenario where dust in early-type systems is likely to be of an external origin.