Surveys for primeval galaxies

Citation

Thompson, David (1995) Surveys for primeval galaxies. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/b644-y527. https://resolver.caltech.edu/CaltechETD:etd-10242007-142316

Abstract

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We present the results from two complementary surveys for young and forming ellipticals or spheroids at high redshift, one based on a narrowband imaging technique using a Fabry-Perot interferometer, and the other a serendipitous long-slit spectroscopic survey.

The Fabry-Perot survey is sensitive to Lya emission in four discrete redshift ranges: z = 2.80 - 2.98, 3.27 - 3.45, 4.42 - 460, and 4.75 - 4.89. The total area of the survey was 0.63 [...], surveyed to a 1[...] limiting line flux of [...] 8.5 x [...] erg [...]. An area of 0.05 [...] was surveyed to a fainter flux limit of [...] 1.5 x [...] erg [...]. A total comoving volume of 110,000 [...] was surveyed to a [...] limiting restframe emission line luminosity of [...] 2.0 x [...] erg [...] (a Friedman cosmology with [...] = 75 km [...] Mpc[...] and [...] = 0.2 is assumed throughout this thesis).

The long-slit survey is sensitive to [...] in the range of 3.1 [...] 5.2, with lesser areas surveyed across the entire optical passband. A total of 421 independent spectroscopic frames were searched, covering an area of 0.0042 [...] (14.97 arcmin[...]). 65 emission-line candidates were identified, including 30 galaxies with [...] and 2 quasars. An additional 20 objects were assigned tentative redshifts, all with [...], and have properties consistent with the galaxies seen in the deep field redshift surveys. The remaining objects are candidate [...] galaxies at high red-shift, with isolated, unidentified emission lines and little or no continuum. They require further spectroscopy to check on their nature. A total comoving volume of 102,600 [...] was surveyed to a [...] limiting restframe emission line luminosity of [...] erg [...].

In neither case was an obvious population of primeval galaxies revealed, despite the combined surveys covering a volume of space sufficient to include [...] 200 galaxies with [...] (using the local space density of massive galaxies, and assuming no density evolution). These galaxies could have been detected if they were unobscured by dust and were actively forming stars at a rate of 100 [...]. A number of candidates remain to be followed up with spectroscopic observations, and may yet prove to be the elusive PGs. The lack of detection of a population of [...]-luminous objects could be due to dust quenching of the [...] line, a higher redshift of formation than surveyed, short lifetime in the [...]-bright phase, or even masking of the star-formation emission-line signature by an active nucleus.

A study on the feasibility of conducting primeval galaxy surveys in the near infrared, based on emission-lines of [0 II], [0 III], and the Balmer lines, and the results of a preliminary survey based on these techniques, are also presented. It is shown that the new large-format infrared arrays will reach the necessary sensitivities over large enough areas to make such surveys practical.

Thesis Files