We describe the far-infrared (far-IR; rest-frame 8-1000-{$μ$}m) properties of a sample of 443 H{$α$}-selected star-forming galaxies in the Cosmic Evolution Survey (COSMOS) and Ultra Deep Survey ... Show moreWe describe the far-infrared (far-IR; rest-frame 8-1000-{$μ$}m) properties of a sample of 443 H{$α$}-selected star-forming galaxies in the Cosmic Evolution Survey (COSMOS) and Ultra Deep Survey (UDS) fields detected by the High-redshift Emission Line Survey (HiZELS) imaging survey. Sources are identified using narrow-band filters in combination with broad-band photometry to uniformly select H{$α$} (and [O II] if available) emitters in a narrow redshift slice at z = 1.47 {\plusmn} 0.02. We use a stacking approach in Spitzer-MIPS mid-IR, Herschel-PACS/SPIRE far-IR [from the PACS Evolutionary Prove (PEP) and Herschel Multi-tiered Extragalactic Survey (HerMES)] and AzTEC mm-wave images to describe their typical far-IR properties. We find that HiZELS galaxies with observed H{$α$} luminosities of L(H{$α$})$_{obs}$ {\ap} 10$^{8.1-9.1}$ L$_{⊙}$ ( {\ap} 10$^{41.7-42.7}$ erg s$^{-1}$) have bolometric far-IR luminosities of typical luminous IR galaxies, L(8-1000 {$μ$} m){\ap} 10\^{}$\{$11.41\^{}$\{$+0.04$\}$\_$\{$-0.06$\}$$\}$ L$_{⊙}$. Combining the H{$α$} and far-IR luminosities, we derive median star formation rates (SFRs) of SFR$_{Hα, FIR}$ = 32 {\plusmn} 5 M$_{⊙}$ yr$^{-1}$ and H{$α$} extinctions of A$_{Hα}$ = 1.0 {\plusmn} 0.2 mag. Perhaps surprisingly, little difference is seen in typical HiZELS extinction levels compared to local star-forming galaxies. We confirm previous empirical stellar mass (M$_{*}$) to A$_{Hα}$ relations and the little or no evolution up to z = 1.47. For HiZELS galaxies (or similar samples) we provide an empirical parametrization of the SFR as a function of rest-frame (u - z) colours and 3.6-{$μ$}m photometry - a useful proxy to aid in the absence of far-IR detections in high-z galaxies. We find that the observed H{$α$} luminosity is a dominant SFR tracer when rest-frame (u - z) colours are {\lsim}0.9 mag or when Spitzer-3.6-{$μ$}m photometry is fainter than 22 mag (Vega) or when stellar masses are lower than 10$^{9.7}$ M$_{⊙}$. We do not find any correlation between the [O II]/H{$α$} and far-IR luminosity, suggesting that this emission line ratio does not trace the extinction of the most obscured star-forming regions, especially in massive galaxies where these dominate. The luminosity-limited HiZELS sample tends to lie above of the so-called main sequence for star-forming galaxies, especially at low stellar masses, indicating high star formation efficiencies in these galaxies. This work has implications for SFR indicators and suggests that obscured star formation is linked to the assembly of stellar mass, with deeper potential wells in massive galaxies providing dense, heavily obscured environments in which stars can form rapidly. Show less
Strong gravitational lenses are now being routinely discovered in wide-field surveys at (sub-)millimeter wavelengths. We present Submillimeter Array (SMA) high-spatial resolution imaging and... Show moreStrong gravitational lenses are now being routinely discovered in wide-field surveys at (sub-)millimeter wavelengths. We present Submillimeter Array (SMA) high-spatial resolution imaging and Gemini-South and Multiple Mirror Telescope optical spectroscopy of strong lens candidates discovered in the two widest extragalactic surveys conducted by the Herschel Space Observatory: the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) and the Herschel Multi-tiered Extragalactic Survey (HerMES). From a sample of 30 Herschel sources with S $_{500}$ {gt} 100 mJy, 21 are strongly lensed (i.e., multiply imaged), 4 are moderately lensed (i.e., singly imaged), and the remainder require additional data to determine their lensing status. We apply a visibility-plane lens modeling technique to the SMA data to recover information about the masses of the lenses as well as the intrinsic (i.e., unlensed) sizes (r $_{half}$) and far-infrared luminosities (L $_{FIR}$) of the lensed submillimeter galaxies (SMGs). The sample of lenses comprises primarily isolated massive galaxies, but includes some groups and clusters as well. Several of the lenses are located at z $_{lens}$ {gt} 0.7, a redshift regime that is inaccessible to lens searches based on Sloan Digital Sky Survey spectroscopy. The lensed SMGs are amplified by factors that are significantly below statistical model predictions given the 500 {$μ$}m flux densities of our sample. We speculate that this may reflect a deficiency in our understanding of the intrinsic sizes and luminosities of the brightest SMGs. The lensed SMGs span nearly one decade in L $_{FIR}$ (median L $_{FIR}$ = 7.9 { imes} 10$^{12}$ L $_{☉}$) and two decades in FIR luminosity surface density (median {$Sigma$}$_{FIR}$ = 6.0 { imes} 10$^{11}$ L $_{☉}$ kpc$^{–2}$). The strong lenses in this sample and others identified via (sub-)mm surveys will provide a wealth of information regarding the astrophysics of galaxy formation and evolution over a wide range in redshift. IMAGING OF HERSCHEL Show less
