Constraining Dust and Molecular Gas Properties in Lyman Alpha Blobs at
  z~3
  In order to constrain the bolometric luminosities, dust properties and
molecular gas content of giant Lyman alpha nebulae, the so-called Lyman alpha
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: a Lya blob
discovered by its strong Spitzer MIPS 24um detection (LABd05; Dey et al. 2005)
and the Steidel blob 1 (SSA22-LAB01; Steidel et al. 2000). We find that the
spectral energy distribution of LABd05 is well described by an AGN-starburst
composite template with L(FIR) = (4.0 +/- 0.5) x 10^12 Lsun, comparable to
high-z sub-millimeter galaxies and ultraluminous infrared galaxies. New
APEX/LABOCA 870um measurements rule out the reported SCUBA detection of the
SSA22-LAB01 (S[850um] = 16.8 mJy) at the > 4sigma level. Consistent with this,
ultra-deep Plateau de Bure Interferometer (PdBI) observations with ~2arcsec
spatial resolution also fail to detect any 1.2mm continuum source down to
~0.45mJy per beam (3sigma). Combined with the existing (sub)mm 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 (Snu dV) < 0.25--1.0 Jy km/s, indicating a modest molecular gas reservoir,
M(H_2) < 1--3 x 10^10 Msun. The non-detections exclude, with high significance
(12 sigma), the previous tentative detection of a CO(4-3) line in the
SSA22-LAB01. The increased sensitivity afforded by ALMA will be critical in
studying molecular gas and dust in these interesting systems.
