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2000MNRAS.315..115D - Mon. Not. R. Astron. Soc., 315, 115-139 (2000/June-2)
The SCUBA Local Universe Galaxy Survey - I. First measurements of the submillimetre luminosity and dust mass functions.
DUNNE L., EALES S., EDMUNDS M., IVISON R., ALEXANDER P. and CLEMENTS D.L.
Abstract (from CDS):
The 60-, 100-, and 850-µm flux densities are well fitted by single-temperature dust spectral energy distributions, with the sample mean and standard deviation for the best-fitting temperature being Td=35.6±4.9K and for the dust emissivity index β=1.3±0.2. The dust temperature was found to correlate with 60-µm luminosity. The low value of β may simply mean that these galaxies contain a significant amount of dust that is colder than these temperatures. We have estimated dust masses from the 850-µm fluxes and from the fitted temperature, although if a colder component at around 20K is present (assuming a β of 2), then the estimated dust masses are a factor of 1.5-3 too low.
We have made the first direct measurements of the submillimetre luminosity function (LF) and of the dust mass function. Unlike the IRAS 60-µm LF, these are well fitted by Schechter functions. The slope of the 850-µm LF at low luminosities is steeper than -2, implying that the LF must flatten at luminosities lower than we probe here. We show that extrapolating the 60-µm LF to 850µm using a single temperature and β does not reproduce the measured submillimetre LF. A population of `cold' galaxies (Td<25K) emitting strongly at submillimetre wavelengths would have been excluded from the 60-µm-selected sample. If such galaxies do exist, then this estimate of the 850-µm flux is biased (it is underestimated). Whether such a population does exist is unknown at present.
We correlate many of the global galaxy properties with the FIR/submillimetre properties. We find that there is a tendency for less luminous galaxies to contain hotter dust and to have a greater star formation efficiency (cf. Young). The average gas-to-dust ratio for the sample is 581±43 (using both the atomic and molecular hydrogen), which is significantly higher than the Galactic value of 160. We believe that this discrepancy is probably due to a `cold dust' component at Td≤20K in our galaxies. There is a surprisingly tight correlation between dust mass and the mass of molecular hydrogen, estimated from CO measurements, with an intrinsic scatter of ≃50per cent.
Abstract Copyright: 2000, Royal Astronomical Society
Journal keyword(s): dust, extinction - galaxies: ISM - galaxies: luminosity function, mass function - galaxies: starburst - infrared: galaxies
Simbad objects: 118
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