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T. E. Pickering, J. M. van der Hulst (Kapteyn Institute)
We present the preliminary results of far-IR and sub-mm observations of low surface brightness (LSB) galaxies. Ten galaxies were observed in the sub-mm at the JCMT using SCUBA of which two were detected at 850 \mum, one of which was also detected at 450 \mum. Combining this sub-mm data with existing IRAS data for these galaxies and assuming a dust emissivity of the form Qem(\lambda) \propto \lambda-\beta we find that the sub-mm fluxes favor a lower value of \beta than is observed in normal galaxies (1 versus 2). One of the objects has a fairly normal derived dust temperature (25--35 K depending on the assumed \beta) while the other is somewhat cooler (15--25 K). Also, the inferred gas-to-dust ratios are quite high for these two objects (500--1000). In addition to the SCUBA observations, we have ISOPHOT observations of a total of 27 galaxies over a range of surface brightnesses. Of this sample, 20 galaxies were detected in at least one band. The derived dust temperatures for the galaxies detected in two or more bands are fairly normal (25--35 K). There is, however, a bias in that the detected galaxies tend to have higher surface brightnesses. None of the very LSB (\muB > 23.5) galaxies were detected and, with a couple of exceptions, the galaxies detected by ISO were also detected by IRAS. The lack of detected dust emission in the lowest surface brightness galaxies is consistent with other lines of evidence, such as their blue colors and low metallicities, that suggest at most modest amounts of dust.
The author(s) of this abstract have provided an email address for comments about the abstract: tim@astro.rug.nl