NOAO >   Observing Info >   Approved Programs >   2001A-0323

Small NOAO Logo

Proposal Information for 2001A-0323


PI: Sandhya Rao, University of Pittsburgh, rao@everest.phyast.pitt.edu
Address: 3941 O'Hara Street, Pittsburgh, PA 15260

CoI: David Turnshek, University of Pittsburgh
CoI: Daniel Nestor, University of Pittsburgh
CoI: Eric Monier, Ohio State University
CoI: Wendy Lane, Kapteyn Institute

Title: Galaxies Associated with Damped and Sub-Damped Ly(alpha) Systems

Abstract: We propose to assemble optical-IR photometric (UBRIJHK) data on galaxies in the fields of 32 QSOs whose absorption spectra indicate that the sight-lines toward them pass through 36 large columns of neutral hydrogen gas with N_HI>10^19 atoms cm^-2. About 44% (16) of the absorption systems are classically termed damped Ly(alpha) (DLA) systems with N_HI\ge2\times10^20 atoms cm^-2, while the remainder are sub-DLA with 10^19<N_HI<2\times10^20 atoms cm^- 2. These systems all have z<1. HST spectroscopy yields precise measures of their HI column densities. Our specific goal is to use multi-color images of these fields to derive photometric redshifts for all the galaxies down to the limit L<0.05-0.1L^*. For each absorption system we will then determine which galaxy is the absorbing galaxy. Further measurements will determine the absorbing galaxies' impact parameters, luminosities, and, when possible, morphological types. We have already assembled a substantial part of this data set and, from our work over the last several years, know that almost all of the DLA galaxies are (unexpectedly) much fainter than L^*. Consequently, the most straightforward way to make substantial future progress is by employing the photometric redshift technique. This work has important significance since it will allow us to determine the nature of the galactic objects that contain the bulk of the neutral hydrogen gas mass in the Universe at z<1.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2001A-0323

noaoprop-help@noao.edu

Small NOAO Logo