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Title: A search for star-forming galaxies at high redshift
Author: Parkes, I. M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1994
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This thesis describes the first search for star formation in primeval galaxies (PGs) at redshifts z ≥ 7. Our method was to undertake deep near-infrared imaging in the J window (~ 1.0 - 1.5μm) using four narrowband filters of 2% FWHM. Over an area of sky of 3.0?1, no emission line object was found to a sensitivity limit of ≈ 10-18 Wm-2. 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≤ z ≤ 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 ≤ z ≤ 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 z = 9, 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 L*(Lyα) of PGs. Two extremes for the bright phase Δtbright of each galaxy are considered. In Case 1, Δtbright spans the four narrowband filters (~ 108 years). In Case 2, the bright period is much shorter, and the specific case of the Partridge & Peebles (1966) model is considered (Δtbright = 3 X 107 years). The 95% confidence limits for Case 1 models constrain L*(Lyα) to less than 1.6 X 1037 W - 4.2 X 1037 W, depending on the cosmological model. These limits are consistent with the Case 1 predictions for Lyα luminosity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available