We use deep observations obtained with the Photodetector Array Camera & Spectrometer ( PACS ) onboard the Herschel space observatory to study the far-infrared ( FIR ) properties of submillimeter and optically faint radio galaxies ( SMGs and OFRGs ) .
From literature we compiled a sample of 35 securely identified SMGs and nine OFRGs located in the GOODS-N and the A2218 fields .
This sample is cross-matched with our PACS 100 \mu m and 160 \mu m multi-wavelength catalogs based on sources-extraction using prior detections at 24 \mu m. About half of the galaxies in our sample are detected in at least the PACS 160 \mu m bandpass .
The dust temperatures and the infrared luminosities of our galaxies are derived by fitting their PACS and SCUBA 850 \mu m ( only the upper limits for the OFRGs ) flux densities with a single modified ( \beta = 1.5 ) black body function .
The median dust temperature of our SMG sample is T _ { dust } = 36 \pm 8 K while for our OFRG sample it is T _ { dust } = 47 \pm 3 K. For both samples , median dust temperatures derived from Herschel data agree well with previous estimates .
In particular , Chapman et al .
( 2005 ) found a dust temperature of T _ { dust } = 36 \pm 7 K for a large sample of SMGs assuming the validity of the FIR/radio correlation ( i.e. , q = log _ { 10 } ( L _ { FIR } [ { W } ] / L _ { 1.4 { GHz } } [ { W Hz ^ { -1 } } ] / 3.75 \times 10 % ^ { 12 } ) ) .
The agreement between our studies confirms that the local FIR/radio correlation effectively holds at high redshift even though we find \langle q \rangle = 2.17 \pm 0.19 , a slightly lower value than that observed in local systems .
The median infrared luminosities of SMGs and OFRGs are 4.6 \times 10 ^ { 12 } L _ { \odot } and 2.6 \times 10 ^ { 12 } L _ { \odot } , respectively .
We note that for both samples the infrared luminosity estimates from the radio part of the spectral energy distribution ( SED ) are accurate , while estimates from the mid-IR are considerably ( \thicksim \times 3 ) more uncertain .
Our observations confirm the remarkably high luminosities of SMGs and thus imply median star-formation rates of 960 M _ { \odot } yr ^ { -1 } for SMGs with S ( 850 \mu { m } ) > 5 mJy and 460 M _ { \odot } yr ^ { -1 } for SMGs with S ( 850 \mu { m } ) > 2 mJy , assuming a Chabrier IMF and no dominant AGN contribution to the far-infrared luminosity .