Open AccessThe contribution of faint blue galaxies to the submillimetre counts and background
Author(s) -
Busswell Geoff S.,
Shanks Tom
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04091.x
Subject(s) - physics , astrophysics , galaxy , qsos , redshift , star formation , astronomy , spiral galaxy , luminous infrared galaxy , source counts , photometric redshift , stellar population
Observations in the submillimetre (submm) waveband have recently revealed a new population of luminous sources. These are proposed to lie at high redshift and to be optically faint because of their high intrinsic dust obscuration. The presence of dust has been previously invoked in optical galaxy count models which use the Bruzual & Charlot evolution models with an exponential τ=9 Gyr star formation rate (SFR) for spirals, and these fit the count data well from U to K . We now show that by using either a 1/ λ or Calzetti absorption law for the dust and re‐distributing the evolved spiral galaxy ultraviolet (UV) radiation into the far‐infrared (FIR), these models can account for all of the ‘faint’ ( 1 mJy) 850‐μm galaxy counts, but fail to fit ‘bright’ ( 2 mJy) sources, indicating that another explanation for the submm counts may apply at brighter fluxes, e.g., quasi‐stellar objects (QSOs) or ultraluminous infrared galaxies (ULIRGs). We find that the main contribution to the faint, submm number counts is in the redshift range 0.5<z<3, peaking at z≈1.8. The above model, using either dust law, can also explain a significant proportion of the extragalactic background at 850 μm, as well as producing a reasonable fit to the bright 60‐μm IRAS counts.