GMOS-South System Verification Plan

The table below summarises the pool of observations which have been defined for GMOS South System Verification. See the GMOS-North SV page for more information about the SV process. A brief description of each program selected for the SV plan follows the table. An announcement requesting SV proposals for other GMOS-S modes (IFU, 2km/s spectroscopy) will be released later in 2003. 

Imaging Mode

Pre-imaging observations required for MOS will be used to test the imaging mode. This includes verification of imaging acquisition procedures, observing sequences, and data reduction pipelines. The programs only requested 9.5 hours for imaging; additional time will be granted to programs which requested imaging so that images can be obtained in additional bandpasses to improve object selection, improve the general usefulness of the dataset, or provide PR images.

Longslit Spectroscopy Mode

GS-2002B-SV-204

GS-2002B-SV-209

We propose to obtain the chemical abundance of four dwarf irregular galaxies of the nearby Centaurus A Group (CEN6, UGCA365, SGC142448-4604 and ESO222-G10). Through Halpha CCD imaging (observed at CTIO; Cote, Skillman, Miller in prep) we have discovered several HII regions in these galaxies, which are amongst the lowest luminosity star-forming galaxies known. Because of the strong correlation between luminosity and abundance in dwarf galaxies, we expect these galaxies to possess some of the most (possibly the most!) primitive chemical environment known, ideal for studying the early stages of nucleosynthesis in galaxies.

This program with demonstrate Gemini/GMOS-S's ability to acquire faint diffuse sources using blind offsets, show the use of placing the slit along the mean parallactic angle, and test the reduction software with emission line sources.

MOS Mode

GS-2002B-SV-206

We propose to obtain images and spectroscopic redshifts of galaxies in X-ray groups at intermediate redshift (0.2< z < 0.4), with the aim of investigating galaxy populations and group properties. The spectra will be used to obtain redshifts, velocity dispersions, and stellar populations of the cluster candidates. It is part of a longer-term program that intends to study a sample of 15 groups with redshifts 0.15 < z < 0.45, with ROSAT x-ray luminosities lower than 10^43.5 ergs/s, selected from the catalog of Vikhlinin et al. (1998). The groups we intend to observe are a factor of 10-100 less luminous in X-ray than clusters identified at the same redshift and are meant to represent the most common types of environments inhabited by galaxies. The data obtained in the current program will contemplate several programs with a common science goal of understanding galaxy evolution in groups of galaxies.

GS-2002B-SV-217

We propose to use GEMINI+GMOS in the MOS mode to obtain the spectra for 50 arcs and arclets in the field of the massive cluster of galaxies Abell 1689. This cluster has deep ACS imaging in the Gunn griz and ground based IR photometry that allow us to compute reliable photometric redshifts in order to preselect the most likely candidates for GMOS. The spectroscopic redshift information will be used to constrain the mass model for the cluster, critical to interpret the much higher redshift magnified galaxies such as the r and i-band dropouts.

Nod&Shuffle Mode

GS-2002B-SV-222

It has been universally accepted for more than a decade that Radio galaxies only occur in elliptical or merging galaxies - except one. That galaxy is 0313-192, and was discovered as part of a large radio survey of Abell clusters (Ledlow & Owen 1995). Extensive followup observations with the VLA, OVRO, Ground based telescopes, and more recently HST have verified the spiral morphology and the uniqueness of this object.

One measurement which would help to elucidate the nature of the central engine in this galaxy is an estimate of the central black-hole mass. We derive consistent estimates of the bulge luminosity from both ground based photometry and HST (B_bulge=-18.7). Based on published correlations between BH mass and bulge luminosity for elliptical galaxies, this corresponds to a BH mass of about 10^8 or lower. This figure is quite low for as powerful an AGN as we are seeing. As the velocity dispersion of the bulge correlates better with black hole mass than the bulge luminosity (Ferrarese et al. 2001), it would be interesting to get a better handle on the range of likely BH masses for this object. Note that this is a very poorly studied part of parameter space for these studies (low bulge luminosity) so it is not clear what are the intrinsic errors from the correlations. An independent measurement will help us to understand the limits and errors.

The velocity dispersion of the bulge can be estimated from the widths of the Ca triplet at rest wavelengths (8498, 8542, and 8662 A). This part of the spectrum is less affected by the central AGN than in the blue. For 0313-192 (z=0.067) these lines are shifted to 9067-9242 Angstroms. While the rest wavelengths conveniently fall in between bright sky emission lines, redward of 9000A the density of sky lines is quite a bit higher. Thus this measurement would require very accurate sky subtraction; a perfect test of the nod-and-shuffle mode of GMOS.

GS-2002B-SV-213

We propose to use 2 nights of GMOS South system verification time to obtain high S/N optical spectra of the 30 reddest galaxies with K < 20 in the well-studied NTT Deep Field. Our aim is to exploit the unique nod-and-shuffle capability of GMOS to obtain spectra for these 30 very/extremely red objects(R-K > 4.5) of a quality comparable to that achieved by Dunlop et al. (1996;1999) for the red radio galaxies 53W091 and 53W069 using single slit spectroscopy on Keck. Our program will be the first to enable robust age-dating of the stellar populations of the oldest galaxies over the redshift range 1 < z < 2.5. The NTT deep field is well matched in size to the GMOS field of view, and at RA = 12hr is ideally placed for the scheduled GMOS-South MOS SV observations. We have combined existing NTT and VLT images to select the target sample, and have in place the necessary efficient modelling tools to derive ages from the flux-calibrated optical spectra on a short time-scale. Spare slits in the mask will be used to attempt to measure redshifts for 20 faint VLA sources and 6 SCUBA sources in this well-studied field, providing further opportunities for headline science, and data of interest to many astronomers within the Gemini community. This proposal will provide an excellent test of the capability of the nod-and-shuffle mode to perform very deep high-quality MOS spectroscopy.

GS-2002B-SV-219

We propose to obtain MOS R600 or R831 spectroscopy to investigate a possible submm-selected cluster at a redshift of 5.74. This would be the highest redshift protocluster ever discovered and hence could prove invaluable for tracing matter density and evaluating models of galaxy formation at very high redshift. We have recently obtained a submm map with SCUBA of the region surrounding the z=5.74 QSO SDSS1044-0125, which shows a second bright submm source within 30" of the quasar (corresponding to ~1Mpc). The probability of such an association occurring by chance is small (~0.01). We have preliminary imaging of this field in RIZK which has identified two possible counterparts to the SCUBA source, one of which may be at very high redshift. We propose to use GMOS to determine the properties of these objects and to search for evidence of other members of this candidate proto-cluster.

This project provides an excellent test of nod/shuffle deep spectroscopy, with the potential for a truly seminal and rapid discovery.

Last update March 10, 2003; Bryan Miller