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Title: Scuba local universe galaxy survey : dust along the Hubble sequence
Author: Vlahakis, Catherine
ISNI:       0000 0004 2747 8514
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2005
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This thesis presents new results from the SCUBA Local Universe Galaxy Survey (SLUGS) the optically-selected sample. SLUGS is the first large systematic submillimetre survey of the local Universe, and was carried out with the SCUBA camera on the James Clerk Maxwell Telescope. Since SCUBA is sensitive to the 90% of dust too cold to radiate significantly in the IRAS bands this new sample, taken from the Center for Astrophysics (CfA) optical redshift survey (Huchra et al. 1983) and hence selected on the basis of optical emission alone, represents the first unbiased survey of dust in galaxies along the whole length of the Hubble sequence. There is little change found in the properties of dust in galaxies along the Hubble sequence, except a marginally significant trend for early-type galaxies to be less luminous submillimetre sources than late-types. Nevertheless, 6 out of 11 elliptical galaxies were detected, although some of the emission may possibly be synchrotron rather than dust emission. The IRAS and submillimetre fluxes are found to be well-fitted by a two-component dust model with dust emissivity index fi=2. The ratio of the mass of cold dust to the mass of warm dust is found to be much higher for the optically-selected galaxies than found for the previous IRAS-selected SLUGS sample (Dunne et al. 2000 Dunne & Eales 2001), and can reach values of 1000. Comparison of the results for the IRAS- and optically-selected samples shows that there is a population of galaxies containing a large proportion of cold dust that is unrepresented in the IRAS sample. Local submillimetre luminosity and dust mass functions are derived, both directly from the optically-selected SLUGS sample, and by extrapolation from the IRAS PSCz survey using the method of Serjeant & Harrison (2005) (by extrapolating the spectral energy distributions of the IRAS PSCz survey galaxies out to 850 /zm we probe a wider range of luminosities than probed directly by the SLUGS samples), and excellent agreement is found between the two. They are found to be well-fitted by Schechter functions except at the highest luminosities. As a consequence of the omission of cold galaxies from the IRAS sample the previous //i45-selected luminosity function is found to be too low by a factor of 2, reducing the amount of cosmic evolution required between the low-z and high-z universe. Finally, the results of the OS SLUGS are used to assess the reliability of the Carilli & Yun (1999, 2000a) radio-submillimetre redshift estimator technique, for the first time using a sample of 'normal' local galaxies.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available