Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-03-09
Astronomy and Astrophysics
Astrophysics
27 pages including 10 figures, accepted for publication in the Astronomical Journal, June 2000, abridged abstract
Scientific paper
10.1086/301368
Science objectives for the Next Generation Space Telescope (NGST) include a large component of galaxy surveys, both imaging and spectroscopy. The Hubble Deep Field datasets include the deepest observations ever made in the ultraviolet, optical and near infrared, reaching depths comparable to that expected for NGST spectroscopy. We present the source counts, galaxy sizes and isophotal filling factors of the HDF-South images. The observed integrated galaxy counts reach >500 galaxies per square arcminute at AB<30. We extend these counts to faint levels in the infrared using models. The trend previously seen that fainter galaxies are smaller, continues to AB=29 in the high resolution HDF-S STIS image, where galaxies have a typical half-light radius of 0.1 arcseconds. Extensive Monte Carlo simulations show that the small measured sizes are not due to selection effects until >29mag. Using the HDF-S NICMOS image, we show that galaxies are smaller in the near infrared than they are in the optical. We analyze the isophotal filling factor of the HDF-S STIS image, and show that this image is mostly empty sky even at the limits of galaxy detection, a conclusion we expect to hold true for NGST spectroscopy. At the surface brightness limits expected for NGST imaging, however, about a quarter of the sky is occupied by the outer isophotes of AB<30 galaxies. We discuss the implications of these data on several design concepts of the NGST near-infrared spectrograph. We compare the effects of resolution and the confusion limit of various designs, as well as the multiplexing advantages of either multi-object or full-field spectroscopy. We argue that the optimal choice for NGST spectroscopy of high redshift galaxies is a multi-object spectrograph (MOS) with target selection by a micro electro mechanical system (MEMS) device.
Gardner Jonathan P.
Satyapal Shobita
No associations
LandOfFree
Counts and Sizes of Galaxies in the Hubble Deep Field - South: Implications for the Next Generation Space Telescope does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Counts and Sizes of Galaxies in the Hubble Deep Field - South: Implications for the Next Generation Space Telescope, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Counts and Sizes of Galaxies in the Hubble Deep Field - South: Implications for the Next Generation Space Telescope will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-653531