Extragalactic Spectroscopy with SIRTF/IRS

The Infrared Spectrograph (IRS) is one of the three instruments on board the Space Infrared Telescope Facility (SIRTF) to be launched in December 2001. The IRS will provide high resolution spectra (R≈600) from 10–37 μm and low resolution spectra (R≥60) from 5–40 μm. Its high sensitivity and “spectral mapping”-mode make it a powerful instrument for observing both faint point-like and extended sources. We discuss the performance of the IRS on faint extragalactic targets and present simulated spectra of starbursts and AGNs at high redshift. In addition, we discuss the determination of redshifts from the low resolution spectra. 1 The Infrared Spectrograph The Infrared Spectrograph (IRS) (Houck & van Cleve, 1995) will provide the Space Infrared Telescope Facility (SIRTF) (Fanson et al. 1998) with low and moderate-spectral resolution spectroscopic capabilities from 4 to 40 microns. The IRS (see Fig. 1) is composed of four separate modules, with two of the modules providing R∼50 spectral resolution over 4 to 40 microns and two modules providing R∼600 spectral resolution over 10 to 37 microns. Fig. 1. The 4 IRS modules on their common base plate.