We present spectroscopic follow-up observations of 70 \mu m selected galaxies from the SWIRE XMMLSS and Lockman Hole fields .
We have measured spectroscopic redshifts for 293 new sources down to a 70 \mu m flux limit of 9mJy and r < 22 mag .
The redshift distribution peaks at z \sim 0.3 and has a high redshift tail out to z = 3.5 .
We perform emission line diagnostics for 91 sources where [ OIII ] , H \beta , [ NII ] , H \alpha and [ SII ] emission lines are available to determine their power source .
We find in our sample 13 QSOs , 1 Seyfert II galaxy , 33 star forming galaxies , 30 composite galaxies , 5 LINERs and 21 ambiguous galaxies .
We fit single temperature dust spectral energy distributions ( SEDs ) to 81 70 \mu m sources with 160 \mu m photometry to estimate dust temperatures and masses .
Assuming the dust emissivity factor ( \beta ) as 1.5 , we determine dust temperatures in the range \sim 20-60K and dust masses with a range of 10 ^ { 6 } -10 ^ { 9 } M _ { \odot } .
Plotting these objects in the luminosity-temperature diagram suggests that these objects have lower dust temperatures than local IR luminous galaxies .
The Herschel Space Observatory will be crucial in understanding the nature of these sources and to accurately determining the shape of the Rayleigh-Jeans tail of the dust SED .
We then model SEDs from optical to far-IR for each source using a set of galaxy and quasar templates in the optical and near-IR ( NIR ) and with a set of dust emission templates ( cirrus , M82 starburst , Arp 220 starburst and AGN dust torus ) in the mid-IR ( MIR ) to far-IR ( FIR ) .
The number of objects fit with each dust template are : 57 Arp 220 , 127 M82 , 9 cirrus , 1 AGN dust torus , 70 M82 and cirrus , 26 M82 and AGN dust torus and 3 Arp 220 and AGN dust torus .
We determine the total IR luminosity ( L _ { \mathrm { IR } } ) in range 10 ^ { 8 } -10 ^ { 15 } L _ { \odot } by integrating the SED models from 8 to 1000 \mu m .