MgII Absorbers at High Redshift Using J-Band High Resolution Spectroscopy on the Hobby-Eberly Telescope

ABSTRACT

AST 0123885

Churchill

This is a Small Grant for Exploratory Research (SGER) project to modify and test an infrared camera and spectrograph (the JCAM) which will be used to obtain spectra on the Hobby-Eberly Telescope (HET) at the McDonald Observatory of the University of Texas. This data will then be used to test the suitability of the modified equipment for measuring spectra of very faint Quasars in the wavelength range of 0.95 to 1.35 millimicrons which corresponds to redshifts of z= 2.4 to 3.8 In the MgII, 2796 - 2803 Angstrom absorption line. The potential scientific impact of obtaining this data for Quasar research is very high. There is a risk that this potentially very important data may not be obtainable with the HET. Extrapolating from the present performance of the telescope in the visual, it is clear that the proposed, modified spectrograph is expected to be useful for obtaining data on sources brighter than V=17 mag. However, the quasars at this redshift range lie in the magnitude range V=18 to 19 mag. Simulations show that the absorption lines in the quasars are detectable against the night sky background for 18th mag objects with an image disk of 1.5 arc seconds but the HET does not at present have the long-term, on-target stability necessary to maintain image sizes of 1.3 to 1.5 arc seconds. Although a telescope upgrade may provide the necessary image quality, the only meaningful way to determine the limiting capabilities of this instrument is to conduct actual tests. Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC).

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