2012ApJ...744..178Y

In order to constrain the bolometric luminosities, dust properties, and molecular gas content of giant Lyα nebulae, the so-called Lyα blobs, we have carried out a study of dust continuum and CO line emission in two well-studied representatives of this population at z ∼ 3: an Lyα blob discovered by its strong Spitzer Multiband Infrared Photometer 24 µm detection (LABd05) and the Steidel blob 1 (SSA22-LAB01). We find that the spectral energy distribution of LABd05 is well described by an active-galactic-nucleus-starburst composite template with L_FIR= (4.0±0.5)x10¹² L_☉, comparable to high-z submillimeter galaxies and ultraluminous infrared galaxies. New Large APEX Bolometer Camera 870 µm measurements rule out the reported Submillimeter Common-User Bolometer Array detection of the SSA22-LAB01 (S _850 µm_= 16.8 mJy) at the >4σ level. Consistent with this, ultradeep Plateau de Bure Interferometer observations with ∼2'' spatial resolution also fail to detect any 1.2 mm continuum source down to ~0.45 mJy/beam (3σ). Combined with the existing (sub)millimeter observations in the literature, we conclude that the FIR luminosity of SSA22-LAB01 remains uncertain. No CO line is detected in either case down to integrated flux limits of S_νΔV ≲ 0.25-1.0 Jy km/s, indicating a modest molecular gas reservoir, M(H₂) < (1-3)x10¹⁰ M_☉. The non-detections exclude, with high significance (12σ), the previous tentative detection of a CO J = 4-3 line in the SSA22-LAB01. The increased sensitivity afforded by the Atacama Large Millimeter/submillimeter Array will be critical in studying molecular gas and dust in these interesting systems.