We present the first results of a multi-wavelength survey , incoporating Herschel-SPIRE , Spitzer , GALEX and ATCA observations , of a 1 ^ { \circ } \times 1 ^ { \circ } field centred on Centaurus A .
As well as detecting the inner lobes of the active galactic nucleus ( AGN ) jet and counterjet , we have found two clouds , bright at sub-mm wavelengths , \sim 15 kpc from the centre of Cen A that are co-aligned with the jets .
Flux measurements at Herschel wavelengths have proved vital in constraining fits to the Spectral Energy Distributions ( SEDs ) .
The clouds are well fit by a single-temperature , modified blackbody spectrum ( \beta = 2 ) indicating that we are looking at two cold dust clouds on the outskirts of Cen A .
The temperature and masses of the clouds are : T _ { north } = 12.6 ^ { +1.1 } _ { -1.2 } K , T _ { south } = 15.1 ^ { +1.7 } _ { -1.6 } K ; log ( M _ { north } / M _ { \odot } ) = 5.8 ^ { +0.2 } _ { -0.2 } , log ( M _ { south } / M _ { \odot } ) = 5.6 ^ { +0.2 } _ { -0.2 } and the gas-dust ratio for both clouds is \sim 100 .
The measured values for the northern dust cloud are consistent with previous measurements from ISO while the southern cloud is a new sub-mm detection .
The two dust clouds are located at the termini of the partial H i ring that surrounds Cen A which is also where the gas column density peaks .
The Herschel survey encompasses the partial H i ring yet we find no evidence of dust emission in any other part of the ring .
Assuming that the gas-dust ratio is the same in the rest of the ring , dust mass upper limits in the H i ring are consistent with low column density dust being present but falling below the SPIRE detection limit .
We have discussed the origin of these clouds and various possible heating mechanisms .
The observations favour a scenario in which the gas and dust were once part of a late-type galaxy which has since merged with Cen A .
The dominant heating mechanism which adequately explains the observed temperatures in both clouds is heating from the evolved stellar population within Cen A .