The average submillimetre properties of Lyman [alpha] blobs at z = 3

• Published in: Monthly notices of the Royal Astronomical Society 2016-08, Vol.460 (4), p.4075
• Main Authors: Hine, N K, Geach, J E, Matsuda, Y, Lehmer, B D, Michalowski, M J, Farrah, D, Spaans, M, Oliver, S J, Smith, D JB, Chapman, S C, Jenness, T, Alexander, D M, Robson, I, vanderWerf, P
• Format: Article
• Language: English
• Subjects: Accretion disks; Astronomy; Luminosity; Star & galaxy formation
• ISSN: 0035-8711; 1365-2966

Ly a blobs (LABs) offer insight into the complex interface between galaxies and their circumgalactic medium. Whilst some LABs have been found to contain luminous star-forming galaxies and active galactic nuclei that could potentially power the Ly a emission, others appear not to be associated with obvious luminous galaxy counterparts. It has been speculated that LABs may be powered by cold gas streaming on to a central galaxy, providing an opportunity to directly observe the 'cold accretion' mode of galaxy growth. Star-forming galaxies in LABs could be dust obscured and therefore detectable only at longer wavelengths. We stack deep Submillimetre Common User Bolometer Array 2 (SCUBA-2) observations of the Small Selected Area 22^sup h^ field to determine the average 850 [mu]m flux density of 34 LABs. We measure S^sub 850^ = 0.6 ± 0.2 mJy for all LABs, but stacking the LABs by size indicates that only the largest third (area [Greater-Than Or Equal To]1794 kpc2) have a mean detection, at 4.5s, with S850 = 1.4 ± 0.3 mJy. Only two LABs (1 and 18) have individual SCUBA-2 >3.5s detections at a depth of 1.1 mJy beam^sup -1^. We consider two possible mechanisms for powering the LABs and find that central star formation is likely to dominate the emission of Ly a, with cold accretion playing a secondary role.