Please use this identifier to cite or link to this item:
The BLAST 250 μm-selected galaxy population in GOODS-South
David Hughes
Acceso Abierto
Galaxies: active
Galaxies: starburst
Galaxies: photometry
Galaxies: fundamental parameters
Infrared: galaxies
We identify and investigate the nature of the 20 brightest 250 μm sources detected by the Balloon-borne Large Aperture Submillimetre Telescope (BLAST) within the central 150 arcmin² of the GOODS-South field. Aided by the available deep VLA 1.4 GHz radio imaging, reaching S₁.₄ ≃ 40 μJy (4-σ), we have identified radio counterparts for 17/20 of the 250 μm sources. The resulting enhanced positional accuracy of ≃ 1 arcsec has then allowed us to exploit the deep optical (HST), near-infrared (VLT) and mid-infrared (Spitzer) imaging of GOODS-South to establish secure galaxy counterparts for the 17 radio-identified sources, and plausible galaxy candidates for the 3 radio-unidentified sources. Confusion is a serious issue for this deep BLAST 250μm survey, due to the large size of the beam. Nevertheless, we argue that our chosen counterparts are significant, and often dominant contributors to the measured BLAST flux densities. For all of these 20 galaxies we have been able to determine spectroscopic (8) or photometric (12) redshifts. The result is the first near-complete redshift distribution for a deep 250 μm-selected galaxy sample. This reveals that 250 μm surveys reaching detection limits of ≃ 40 mJy have a median redshift z ≃ 1, and contain not only low-redshift spirals/LIRGs, but also the extreme z ≃ 2 dust-enshrouded starburst galaxies previously discovered at sub-millimetre wavelengths. Inspection of the LABOCA 870 μm imaging of GOODS-South yields detections of ≃ 1/3 of the proposed BLAST sources (all at z > 1.5), and reveals 250/870 μm flux-density ratios consistent with a standard 40K modified black-body fit with a dust emissivity index β = 1.5. Based on their IRAC colours, we find that virtually all of the BLAST galaxy identifications appear better described as analogues of the M82 starburst galaxy, or Sc star-forming discs rather than highly obscured ULIRGs. This is perhaps as expected at low redshift, where the 250 μm BLAST selection function is biased towards spectral energy distributions which peak longward of λrest = 100 μm. However, it also appears largely true at z ≃ 2.
Monthly Notices of the Royal Astronomical Society
Público en general
Dunlop, J. S., et al., (2010). The BLAST 250 μm-selected galaxy population in GOODS-South, Monthly Notices of the Royal Astronomical Society. Vol. 408(4):2022–2050
Versión aceptada
acceptedVersion - Versión aceptada
Appears in Collections:Artículos de Astrofísica

Upload archives

File SizeFormat 
18.-A_3.pdf2.19 MBAdobe PDFView/Open