The average submillimetre properties of Lyman-alpha Blobs at z=3

Hine, N K, Geach, J E, Matsuda, Y, Lehmer, B D, Michalowski, M J, Farrah, D, Spaans, M, Oliver, S J, Smith, D J B, Chapman, S C, Jenness, T, Alexander, D M, Robson, I and van der Werf, P (2016) The average submillimetre properties of Lyman-alpha Blobs at z=3. Monthly Notices Of The Royal Astronomical Society, 460 (4). pp. 4075-4085. ISSN 0035-8711

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Ly-alpha 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-alpha 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 SCUBA-2 observations of the SSA22 field to determine the average 850um flux density of 34 LABs. We measure S_850 = 0.6 +/- 0.2mJy for all LABs, but stacking the LABs by size indicates that only the largest third (area > 1794 kpc^2) have a mean detection, at 4.5 sigma, with S_850 = 1.4 +/- 0.3mJy. Only two LABs (1 and 18) have individual SCUBA-2 > 3.5 sigma detections at a depth of 1.1mJy/beam. We consider two possible mechanisms for powering the LABs and find that central star formation is likely to dominate the emission of Ly-alpha, with cold accretion playing a secondary role.

Item Type: Article
Keywords: Galaxies: evolution, Galaxies: protoclusters, Galaxies: formation, Galaxies: high-redshift
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
Depositing User: Richard Chambers
Date Deposited: 18 May 2016 16:03
Last Modified: 07 Mar 2017 07:33

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