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The spectral appearance of primeval galaxies

ASTR SOC P 200 (1999) 299-308

Authors:

B Guiderdoni, JEG Devriendt

Abstract:

The current and forthcoming observations of large samples of high-redshift galaxies selected according to various photometric and spectroscopic criteria can be interpreted in the context of galaxy formation, by means of models of evolving spectral energy distributions (SEDs). We hereafter present STARDUST which gives synthetic SEDs from the far UV to the submm wavelength range. These SEDs are designed to be implemented into semi-analytic models of galaxy formation.
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The GEMINI multiobject spectrographs

Proceedings of SPIE - The International Society for Optical Engineering 3355 (1998) 188-195

Authors:

R Murowinski, T Bond, D Crampton, T Davidge, JM Fletcher, B Leckie, C Morbey, S Roberts, L Saddlemyer, J Sebesta, J Stilburn, K Szeto, JR Allington-Smith, R Content, RL Davies, G Dodsworth, R Haynes, D Robinson, D Robertson, J Webster, D Lee, S Beard, C Dickson, D Kelly, R Bennet, M Ellis, P Hastings, P Williams

Abstract:

As the only two optical instruments appearing in its first fleet of instrumentation, the GEMINI MultiObject Spectrograph (GMOS) are indeed being developed as workhorse instruments. One GMOS will be located at each of the GEMINI telescopes to perform: a) exquisite direct imaging, b) 5.5 arcminute longslit spectroscopy, c) up to 600 object multislit spectroscopy, and d) about 2000 element integral field spectroscopy. The GMOSs are the only GEMINI instrumentation duplicated at both telescopes. The UK and Canadian GMOS team successfully completed their critical design review in February 1997. They are now well into the fabrication phase, and will soon approach integration of the first instrument. The first GMOS is scheduled to be delivered to Mauna Kea in the fall of'99 and the second to Cerro Pachon one year later. In this paper, we will look at how a few of the more interesting details of the final GMOS design help meet its demanding scientific requirements. These include its transmissive optical design and mask handling mechanisms. We will also discuss our plans for the mask handling process in GEMINI'S queue scheduled environment, from the taking of direct images through to the use of masks on the telescope. Finally, we present the status of fabrication and integration work to date.
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The 2dF QSO Redshift Survey

ArXiv astro-ph/9810127 (1998)

Authors:

SM Croom, T Shanks, BJ Boyle, RJ Smith, L Miller, NS Loaring

Abstract:

We present preliminary results from the 2-degree Field (2dF) QSO Redshift Survey currently under way at the Anglo-Australian Telescope. This survey aims to determine the redshifts of >25000 QSOs over a redshift range of 0.3
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The galaxy halo formation rate

ArXiv astro-ph/9809330 (1998)

Authors:

WJ Percival, L Miller

Abstract:

The rate at which galaxy halos form is thought to play a key role in explaining many observable cosmological phenomena such as the initial epoch at which luminous matter forms and the distribution of active galaxies. Here we show how Press-Schechter theory can be used to provide a simple, completely analytic model of the halo formation rate. This model shows good agreement with both Monte-Carlo and N-body simulation results.
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Contribution of galaxies to the background hydrogen-ionizing flux

Monthly Notices of the Royal Astronomical Society 298:3 (1998) 708-718

Authors:

JEG Devriendt, SK Sethi, B Guiderdoni, BB Nath

Abstract:

We estimate the evolution of the contribution of galaxies to the cosmic background flux at 912 Å by means of a semi-analytic model of galaxy formation and evolution. Such modelling has been quite successful in reproducing the optical properties of galaxies. We assume that high-redshift damped Lyman α systems are the progenitors of present-day galaxies, and we design a series of models that are consistent with the evolution of cosmic comoving emissivities in the available near-infrared, optical, ultraviolet and far-infrared bands along with the evolution of the neutral hydrogen content and average metallicity of damped Lyman α systems. We use these models to compute the galactic contribution to the Lyman-limit emissivity and background flux for 0 ≃ z ≤ 4. We take into account the absorption of Lyman-limit photons by HI and dust in the interstellar medium of the galaxies. We find that the background Lyman-limit flux due to galaxies might dominate (or be comparable to) the contribution from quasars at almost all redshifts if the absorption by HI in the interstellar medium is neglected. Such HI absorption would result in a severe diminishing of this flux - by almost three orders of magnitude at high redshifts and by one to two orders at z ≃ 0. Though the resulting galaxy flux is completely negligible at high redshifts, it is comparable to the quasar flux at z ≃ 0.
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