This thesis describes the first search for star formation in primeval galaxies (PGs) at redshifts <I>z</I> ≥ 7. Our method was to undertake deep near-infrared imaging in the J window (~ 1.0 - 1.5<I>μ</I>m) using four narrowband filters of 2% FWHM. Over an area of sky of 3.0<SUP>?1</SUP>, no emission line object was found to a sensitivity limit of ≈ 10<SUP>-18</SUP> Wm<SUP>-2</SUP>. Interpreting this limit in terms of a limit on Lyα emission, it has been possible to place the first constraints on star formation at redshifts 7≤ <I>z</I> ≤ 9. The search is also sensitive to other emission lines at lower redshifts, of particular interest are the constraints placed on Hα emission. This line is a direct tracer of star formation (Kennicutt et al., 1987) and, at the wavelengths of the narrowband filter, it probes redshifts 0.5 ≤ <I>z</I> ≤ 0.9. Constraints on the star formation rate at these redshifts are of great interest in the interpretation of the excess of faint blue objects seen in number counts (Tyson 1988, Lilly et al. 1991, Metcalfe et al. 1991, Jones et al., 1991). By assuming that there is no evolution in the comoving number density of galaxies out to <I>z = 9, </I>and that the luminosity function of objects at these redshifts can be represented by a Schechter function, it is possible to use the limits of the IRCAM search to place constraints on the characteristic Lyα luminosity <I>L</I>*(Lyα) of PGs. Two extremes for the bright phase Δ<I>t</I><SUB>bright</SUB> of each galaxy are considered. In Case 1, Δ<I>t</I><SUB>bright</SUB> spans the four narrowband filters (~ 10<SUP>8</SUP> years). In Case 2, the bright period is much shorter, and the specific case of the Partridge & Peebles (1966) model is considered (Δ<I>t</I><SUB>bright</SUB> = 3 X 10<SUP>7</SUP> years). The 95% confidence limits for Case 1 models constrain <I>L</I>*(Lyα) to less than 1.6 X 10<SUP>37</SUP> W - 4.2 X 10<SUP>37</SUP> W, depending on the cosmological model. These limits are consistent with the Case 1 predictions for Lyα luminosity.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:660361 |
| Date | January 1994 |
| Creators | Parkes, I. M. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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