The average submillimetre properties of Lyman α blobs at z = 3

Hine, N.K.; Geach, J.E.; Matsuda, Y.; Lehmer, B.D.; Michałowski, M.J.; Farrah, D.; Spaans, M.; Oliver, S.J.; Smith, D.J.B.; Chapman, S.C.; Jenness, T.; Alexander, D.M.; Robson, I.; van der Werf, P.

Abstract

Ly α 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 α 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 22h field to determine the average 850 μm flux density of 34 LABs. We measure S850 = 0.6 ± 0.2 mJy for all LABs, but stacking the LABs by size indicates that only the largest third (area ≥1794 kpc2) have a mean detection, at 4.5σ, with S850 = 1.4 ± 0.3 mJy. Only two LABs (1 and 18) have individual SCUBA-2 >3.5σ detections at a depth of 1.1 mJy beam−1. We consider two possible mechanisms for powering the LABs and find that central star formation is likely to dominate the emission of Ly α, with cold accretion playing a secondary role.

Citation

Hine, N., Geach, J., Matsuda, Y., Lehmer, B., Michałowski, M., Farrah, D., …van der Werf, P. (2016). The average submillimetre properties of Lyman α blobs at z = 3. Monthly Notices of the Royal Astronomical Society, 460(4), 4075-4085. https://doi.org/10.1093/mnras/stw1185

• Journal Article Type: Article
• Acceptance Date: May 16, 2016
• Online Publication Date: Jun 8, 2016
• Publication Date: Aug 21, 2016
• Deposit Date: Jun 21, 2017
• Publicly Available Date: Jun 30, 2017
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 460
• Issue: 4
• Pages: 4075-4085
• DOI: https://doi.org/10.1093/mnras/stw1185
• Public URL: https://durham-repository.worktribe.com/output/1376272