[Mayan calendar]

2001B Gemini North Queue Program Abstracts

Abstracts for all successful 2001B queue programs on Gemini North are given below.


GN-2001B-Q-1

Title: A Near-IR study of optically ambiguous Seyfert 2's: Implications for the Starburst-AGN connection

Abstract: Optical-UV studies have established the existence of a starburst-AGN connection in Seyfert 2 galaxies (Sy2), a connection which is believed to extend to the epoch of the formation of bulges and ellipticals. Near-IR (NIR) spectroscopy offers a unique opportunity of tackle this issue more closely, overcoming the severe difficulties in the optical-UV detection of starbursts in Sy's while simultaneously probing deeper into dusty regions and providing reliable stellar population diagnostics. We propose a NIR study of Sy2'with ambiguous optical properties. They all show a strong ``featureless continuum'' which, unlike for bona fide composite starburst+Sy2 galaxies, cannot be unambiguously attributed to young stars because of the limitations of optical diagnostics. As many as 1/3 of Sy2's belong to this ambiguous category. The NIR data will allow us to break this degeneracy by determining whether or not they contain starbursts. This will help us figure how this sizeable portion of the Sy2 population fits into the emerging scenario for the starburst-AGN connection.


GN-2001B-Q-10

Title: Galaxy Evolution During Half the Age of the Universe

Abstract: Detailed studies of nearby galaxies (z<0.05) have shown that galaxies have very complex histories of formation and evolution involving mergers, bursts of star formation, and morphological changes. Even so, the global properties of the galaxies (radii, luminosities, rotation velocities, velocity dispersions, and absorption line strengths) follow a number of very tight (empirical) scaling relations, e.g. the Tully-Fisher relation and the Fundamental Plane. These relations place constraints on models for galaxy evolution. The results for nearby galaxies rely on high signal-to-noise spectroscopy and multi-color photometry. With the Gemini Telescopes it is now possible to carry out similar detailed studies of galaxies at much larger redshifts, upt to z~0.9, equivalent to half the age of the Universe. We propose to use GMOS to obtain spectroscopy and photometry of galaxies in Abell 851 and RXJ1347.5-1145, two rich clusters at z=0.4-0.45. The observations are the first in a larger project aimed at studying the galaxy evolution over the last half of the age of the Universe based on a large database of spectroscopy and photometry of galaxies in 15 rich clusters of galaxies with redshifts between 0.15 and 0.9. The present proposal is coordinated with a proposal submitted to the UK TAC for similar observations of the cluster Abell 963 at z=0.2 (PI: Roger Davies).


GN-2001B-Q-11

Title: Constraining the Lifetimes of Circumstellar Disks:L band Observations of NGC 2362

Abstract: We propose to obtain deep JHKL' imaging of 200 stars in the young stellar cluster NGC 2362 using NIRI on Gemini North. We have shown that the combination of JHKL imaging photometry is capable of detecting essentially all of the circumstellar disks around young stars. Our proposed Gemini observations are critical for our overall program to determine the frequency and lifetimes of circumstellar disks in young stellar clusters, the preferred sites of star formation in our Galaxy. NGC 2362 is key to this program since it has an age of 5 Myrs. From our previous observations, this age is roughly equal to the timescale over which circumstellar disks are estimated to dissipate. The main goals of these proposed observations are to determine if the circumstellar disk fraction of all stars in NGC 2362, down to the hydrogen burning limit, is significantly reduced, as expected from its age and to test if the lifetimes of circumstellar disks are a function of stellar mass. This proposal was awarded 5 hours on Gemini North with NIRI during the 2001A semester with a ranking of 1. However, no observations were obtained due to the delay of the 1st NIRI queue.


GN-2001B-Q-12

Title: Direct Comparison of Optical and Infrared Searches for High-Redshift Galaxies: How Much of the Young Universe has been Obscured by Dust?

Abstract: The leading uncertainty in our knowledge of star formation in the young universe is the amount of luminosity that is absorbed (and then re-reradiated) by dust grains. We will use NIRI in a narrowband imaging search for high-redshift emission-line galaxies ([OIII]5007 at z=3.3-3.4 and H(alpha) at z=2.2-2.3). The wide areal coverage of optically-studied fields will allow the first direct quantitative comparison of this successful search method with the Lyman break method, which uses optical photometry to measure the far-UV rest-frame continuum of z >= 3 galaxies. Because of its large number of pixels, NIRI is the only instrument in the world currently fast enough to do this project (Keck would be a factor of 10 slower). We suspect that the Lyman break method is missing at least half of all high-z galaxies, because their far-UV continuum is reddened by dust. If so, our search of previously studied LBG fields in only 2 nights will determine this. We will detect at least 16-20 galaxies at z ~ 3.3, the majority of which were previously missed.


GN-2001B-Q-13

Title: Classification of young brown dwarfs and planetary mass objects in Orion

Abstract: We propose to obtain red (650-1000 nm) spectra with GMOS of a sample of candidate substellar objects in Orion identified through infrared photometry and spectroscopy. We wish to observe a field centred about 2.5 arcmin south-west of the Trapezium stars where almost all of the planetary mass candidates have been detected and the nebular background is much fainter than in the core. In a single GMOS field, we will be able to measure about 13 planetary mass candidates (M<13 M(jupiter)), 5 anomalously blue objects (which probably have circumstellar emission) and >30 brown dwarf candidates; the exact number depends upon the optimum instrument configuration. The spectra will allow us to estimate the spectral types using the temperatures andsurface gravities obtained by reference to stellar models. They will also allow us to place firm limits on the contamination of our sample by revealing any foreground or background objects (which will have markedly different specra). This data set will provide the first optical spectra of these young (~1My) low-mass objects with sufficient resolution to investigate atomic and molecular features and, in combination with the existing UFTI photometry, will give us a first look at the H-R diagram. IR spectra taken with CGS4 have shown that the water vapour bands near 1.6microns have distinct profiles, which are qualititatively matched by low gravity models; we may well find some unexpected features in the optical spectra and/or the H-R diagram.


GN-2001B-Q-14

Title: Measuring the Universe to z=1.2 with SN Ia

Abstract: Type Ia supernovae provide evidence for an accelerating universe, an extraodinary result that needs to be regorously tested. The case for cosmic acceleration rests almost entirely on the observation that the observed SN Ia at z~0.5 are 0.25 magnitudes fainter than expected for a non-accelerating Universe. We propose to follow 10 SN Ia in the range 0.9<z<1.2 using Gemini in J (restframe V) as part of a world-wide program using Gemini, HST, Subaru, Keck, VLT and the CFHT. We can expect to measure the mean luminosity distance of the sample at z~1.05 to better than 0.07 mag. At these redshifts the effect of Lambda has all but vanished and the Universe was decelerating due to its known matter content. Because any simple systematic error will deviate substantially from the non-monotonic affect of a Lambda cosmology, this experiment is a powerful and straightforward way to assess the reliability of the SN Ia measurements. In addition, if the SN Ia are reliable standard candles, the proposed observations will significantly increase the precision at which we measure the amount of Lambda and Matter in the Universe, and our ability to see if something other than lambda is leading to the acceleration.


GN-2001B-Q-15

Title: Search for Gravitational Arcs in X-Ray Luminous clusters

Abstract: We propose a systematic search of gravitational arc(let)s in a complete sample of 24 X-ray luminous clusters, to study the mass distribution in their very central regions. Their detection probability has been estimated to be considerably larger than previously thought (Cypriano et al. 2001) when deep images under very good seeing conditions are employed. Due to its large collecting area and its superlative image quality, Gemini is the ideal telescope to perform this project. The proposed imaging will also allow the measurement of weak-shear, which shall be used together with the detections of strong lensing for mapping their central mass profiles.

We expect to find at least 14 new giant arcs by surveying our whole sample.


GN-2001B-Q-16

Title: Type Ia Supernovae in the Epoch of Deceleration

Abstract: We propose to find, and follow, 10-25 Type Ia supernovae in the redshift range 0.9<z<1.2. These supernovae will be used to establish another point on the cosmological world line which will verify our results that Omega_Lambda > 0, or show that our technique is affected by systematic errors or unaccounted systematic effects. Such systematic effects, such as dust or a simple scale error which is linear in z, will make the distant supernovae too faint with respect to a Omega_Lambda > 0 cosmology. At z>0.9, an (Omega_M, Omega_Lambda)=(0.3,0.7) universe will be in deceleration, causing the supernovae to begin to brighten relative to an empty model. We will search for these SNe at Subaru and CFHT, obtain followup spectra at Keck and the VLT, and follow the optical photometry in U(R), B(I,Z), with HST, the Hawaii time, and with the Gemini-S Acquistion Camera. The most critical aspect of the proposal before you is to get V(J) data with Gemini-N NIRI, to allow us to measure colors of the supernovae near maximum light.


GN-2001B-Q-17

Title: Measuring the Universe to z=1.2 with SN Ia

Abstract: Type Ia supernovae provide evidence for an accelerating universe, an extraodinary result that needs to be regorously tested. The case for cosmic acceleration rests almost entirely on the observation that the observed SN Ia at z~0.5 are 0.25 magnitudes fainter than expected for a non-accelerating Universe. We propose to follow 10 SN Ia in the range 0.9<z<1.2 using Gemini in J (restframe V) as part of a world-wide program using Gemini, HST, Subaru, Keck, VLT and the CFHT. We can expect to measure the mean luminosity distance of the sample at z~1.05 to better than 0.07 mag. At these redshifts the effect of Lambda has all but vanished and the Universe was decelerating due to its known matter content. Because any simple systematic error will deviate substantially from the non-monotonic affect of a Lambda cosmology, this experiment is a powerful and straightforward way to assess the reliability of the SN Ia measurements. In addition, if the SN Ia are reliable standard candles, the proposed observations will significantly increase the precision at which we measure the amount of Lambda and Matter in the Universe, and our ability to see if something other than lambda is leading to the acceleration.


GN-2001B-Q-18

Title: Massive stars in NGC 604: where is the next generation?

Abstract: Giant HII regions (GHIIRs) are among the most luminous objects that can be observed in distant galaxies. In these regions, star formation occurs at extremely high rates. In the Local Group there are two GHIIRs that stand out as the most important starbursts: 30 Doradus in the LMC and NGC 604 in M33.

NGC 604 presents a core of massive stars surrounded by nebular filamentary structures, showing a striking similarity with those observed in 30 Dor. Molecular clouds associated to the ionizing cluster NGC604 region have been detected in CO, and bright infrared sources became apparent from the latest IR survey from 2MASS. This may be interpreted as evidence towards the existence of a second generation of young massive stars is being born in the boundaries of a molecular cloud.

We propose to perform JHKs broadband imaging of NGC604 to investigate the presence of a new stellar young and massive generation of stars. These observations will allow us to produce color-color and color-magnitude diagrams for the IR sources found there. This information will be used to establish the NIR photometric characteristics of the massive star cluster in the core of NGC 604 and the interface between the ionized cavity and the giant molecular cloud.

Note: this is a re-submission of a proposal which was awarded Band 1 telescope time on the first QS run but was not observed due to weather/technical problems with the telescope and Hokupa'a.


GN-2001B-Q-19

Title: Imaging extra-solar planets

Abstract: We propose to obtain deep, near-IR (J) images of young, nearby white dwarfs, to detect massive planetary companions (>3Mj). Since the white dwarfs are evolved from 1.5-4 Msol stars, we will in effect be probing the frequency of massive companions to solar type (and more massive) stars. Radial velocity surveys are heavily biased towards massive, short period planets and provide little or no information on systems with massive planets at large radii, such as our own. Our observations will probe exactly this region. By targeting white dwarfs we will obtain better contrast and angular separation (due to outward movement of the planets during primary mass loss) than surveys around main-sequence stars. These observations will, therefore, provide significant constraints on the frequency of massive planetary companions to solar-type (and more massive) stars, and potentially provide the first sample of extra-solar planets that can be directly observed.


GN-2001B-Q-2

Title: Probing the high redshift Universe via quasars with z>5

Abstract: GMOS will be used to obtain identification spectra of redshift 5-7 quasars for a project whose ultimate goals are: (1) To establish the contribution of AGN to the integrated extragalactic ultraviolet background light at the highest possible redshifts. (2) To establish unambiguously the rate of decline in the space density of quasars out to a redshift of about 6.5 via the explicit detection of the characteristic `knee' in the quasar luminosity function ; (3) To determine the epoch of reionization via the Gunn-Peterson test; (4) To identify a sample of z>5 damped Lyman alpha absorbers

The quasar candidates have been robustly selected from our recent deep imaging survey at CFHT, a survey that goes more than two magnitudes fainter than the Sloan survey and hence includes quasars well below the bright end of the QSO luminosity function.


GN-2001B-Q-20

Title: Quantitative analysis of the peculiar Wolf-Rayet population in the starburst galaxy IC 10

Abstract: We seek high S/N GMOS spectra of ~ 30 individual Wolf-Rayet (WR) stars in the Local Group starburst galaxy IC 10 to accurately determine their surface chemistry, mass loss rate, temperature and luminosity. This will serve two purposes: (a) provide a crucial test of current evolutionary models and radiatively driven wind theory in the late stages of evolution of massive stars, and (b) provide a better understanding of the current starbust episode in the most active star-forming galaxy in the Local Group.


GN-2001B-Q-21

Title: The Extended Star Formation Histories of the M81 Group dwarf Ellipticals F8D1 and BK 5N

Abstract: We propose to use NIRI to image in the J and K bands the dwarf elliptical (dE) galaxies F8D1 and BK 5N. These dwarfs are members of the M81 group, one of the nearest groups beyond the Local Group. Our HST/WFPC2 study (in the V and I bands; Caldwell et al., 1998, AJ, 115, 535) has revealed the presence of significant numbers of stars above the tip of the red giant branch in both galaxies, an indication of the presence of an intermediate-age (~2 < age < ~10 Gyr) population. Near-IR band photometry is required, however, to determine bolometric magnitudes for these upper-AGB stars, and thus provide improved estimates of their ages. Our results will provide information on the extended epochs of star formation in these dwarf ellipticals which will be directly comparable to existing information for Local Group dEs, such as the dwarf spheroidal companions to the Galaxy and to M31. In this way we will add to the understanding of the factors, including environment, that govern the star formation history in these allegedly simple galaxies.


GN-2001B-Q-22

Title: Probing the Star Formation History at z>=5

Abstract: Quasars at high redshift (z>=3) show solar or even enhanced metallicities which require an intense previous star formation phase. We can potentially date the first star formation episode in the early universe using the abundance ratio iron/alpha -elements. Nucleosynthesis time scales for iron are significantly different than for alpha-elements (e.g. oxygen, magnesium, or silicon) leading to an enrichment delay of the order of ~1 Gyr for iron. If the iron emission lines in high-redshift quasars (z>=5) are attributed to solar or higher Fe/alpha ratios, then the first star formation epoch would start at redshift z~10, corresponding to an age of the universe less than ~5 x 10^8 years (H_o=65 km s^{-1} Mpc^{-1}, q_o=0.15). We will measure broad FeII emission features and the MgII 2798 emission line for 3 quasars at redshifts z>=5. We will analyse these quasar spectra by applying theoretical as well as empirical templates of the FeII lines, and Balmer continuum emission. We apply for 11 hours queue observing time with Gemini North using NIRI.


GN-2001B-Q-23

Title: Quantitative analysis of the peculiar Wolf-Rayet population in the starburst galaxy IC 10

Abstract: We seek high S/N GMOS spectra of ~ 30 individual Wolf-Rayet (WR) stars in the Local Group starburst galaxy IC 10 to accurately determine their surface chemistry, mass loss rate, temperature and luminosity. This will serve two purposes: (a) provide a crucial test of current evolutionary models and radiatively driven wind theory in the late stages of evolution of massive stars, and (b) provide a better understanding of the current starbust episode in the most active star-forming galaxy in the Local Group.


GN-2001B-Q-24

Title: Circumstellar Disks around Brown Dwarfs in the Trapezium Cluster

Abstract: We propose to obtain deep L' observations of the Trapezium cluster in order to confirm the presence of circumstellar disks around a large fraction of the candidate brown dwarf population in the cluster. From deep JHK observations of the cluster, obtained with the ESO NTT, we discovered a very large fraction (47/77 or 60%) of the brown dwarf candidates to be characterized by strong JHK infrared excess, indicating the extreme youth of these objects and providing strong evidence for their substellar nature. Moreover, these observations suggest that, like their stellar counterparts, circumstellar disks surround most brown dwarfs in the cluster. However, longer wavelength observations are necessary to both confirm the presence of such disks and obtain an accurate census of their numbers. In so doing, the proposed Gemini observations will directly test theories of brown dwarf origins.


GN-2001B-Q-25

Title: Metallicities of 0.5 < z < 1.0 galaxies

Abstract: We are undertaking a program of optical/NIR emission-line spectroscopy of 0.5 < z < 1.0 star-forming CFRS galaxies to measure their ISM metallicities. Preliminary results, based on the optical lines, suggest high metallicities, around solar, at variance with the conventional idea that these objects are brightened dwarfs. However, near-IR observations of Halpha, [NII] and [SII] are required to (a) break the low versus high metallity-degeneracy in the optical; (b) discriminate between low metallicity objects and AGN; (c) correct for reddening on an object-by-object basis, and thus to firmly establish this interesting result.


GN-2001B-Q-26

Title: A Methane-Break Imaging Survey in Orion

Abstract: We propose to search in the Trapezium cluster in Orion for free-floating planets of 1--3 Mjup. We will obtain deep Gemini/NIRI imaging using a pair of moderate-bandwidth filters tuned to the 1.6 micron CH4 break in the spectra of ultracool objects. The Trapezium cluster is the ideal target given its proximity, youth, compactness, and richness; and it can only be observed in the fall. This technique is essentially unexploited --- only with the advent of Gemini/NIRI is this experiment possible. This work is a new and timely scientific opportunity to measure the IMF to unprecedentedly low masses.


GN-2001B-Q-27

Title: A Census of z > 4 Galaxies

Abstract: Recent years have seen many discoveries of high redshift galaxies. There are 33 known galaxies at z>4.2. We will triple that number with spectroscopy at Gemini. The candidates for spectroscopic followup are Lyman break galaxies (LBGs) from the NOAO Deep Widefield Survey (NDWFS) and Ly(alpha) emitters (LAEs) from the Large Area Lyman Alpha (LALA) survey. These two surveys apply complementary selection methods to the same fields to yield the most complete optically selected sample possible: The LAEs include systems with lower bolometric luminosities and higher Ly(alpha) equivalent widths than the LBGs, suggesting that they have very young stellar populations (< 10^7 years old) and little or no dust. Combining our surveys will allow us to explore the overlap between traditional LBG and LAE samples by finding galaxies with intermediate properties. The spectroscopic sample will also help refine photometric classification methods that can leverage much larger high-redshift samples from LALA and NDWF surveys, which provide unprecedented combinations of volume and sensitivity. We will use both spectroscopic and photometric redshifts to determine luminosity functions, star formation rates, and clustering properties of the high redshift galaxy sample as a whole. We will also study the relationship between the continuum- and line-selected galaxies. Finally, we will combine our z ~ 5.7 and z ~ 4.5 data with lower redshift samples from the literature to study galaxy evolution over the range 2.4 < z < 5.8.


GN-2001B-Q-28

Title: Testing White Dwarf Cosmochronology in M67

Abstract: We plan on employing the new capabilities of GMOS as part of an attack on the problem of using the luminosity function of cooling white dwarfs to constrain the age of the oldest stars. With only a modest extrapolation this will eventually provide a constraint on the age of the Universe itself. We are currently studying this problem in a number of environments, from young open star clusters through to ancient globular clusters and the Galactic halo, and with a range of telescopes including CFHT, HST and Gemini. M67 is an important part of this program as the oldest open star cluster for which the termination of the cooling sequence is well defined and for which spectroscopy of its faintest members is feasible with 8m class telescopes. The location of the end of the white dwarf cooling sequence in M67 is currently identified purely by statistical methods. With this proposal we will obtain spectroscopy of candidate white dwarfs to the limit of the cooling sequence (V = 24.2) thus eliminating extragalactic and other stellar interlopers and providing the first ever confirmed white dwarf cooling age of a star cluster. In addition, the spectroscopy of these stars will provide crucial information into the white dwarf initial-final mass relationship, the upper mass limit to white dwarf production, the DA/DB spectral segregation of the stars, white dwarf surface gravities and the slope of the white dwarf luminosity function.


GN-2001B-Q-29

Title: Using the Ca II triplet to disentangle age, metallicity and dynamical properties of Leo I

Abstract: It is critical to our understanding of galaxy evolution to determine how the fraction of metals in a galaxy is built up over time, and resolved stellar populations in nearby galaxies afford the best places to study this in the most detail. Photometric determinations of metallicity evolution from Colour-Magnitude diagram analyses suffer from age-metallicity degeneracy, but if metallicity information can be added to the photometric analysis it is possible to break the degeneracy and uniquely determine the age of stars of known metallicity. This makes it possible to directly measure how the metallicity of a stellar population has varied over the lifetime of a galaxy. The Ca II triplet absorption index is a tried and tested, convenient and independent way to measure the relative metallicities of evolved red giant stars, which cover the age range 1-10Gyr ago. The Ca II triplet absorption lines can also be used to determine accurate radial velocities of individual stars in a galaxy. In this project we plan to use GMOS on Gemini-North to determine the relationship between star-formation, chemical evolution and dynamics in a nearby dwarf spheroidal galaxy, Leo I, which is known from previous photometric studies to have a very complex star-formation history which will never be uniquely determined with out spectroscopic abundance determinations.


GN-2001B-Q-3

Title: Fundamental Properties of Elliptical Galaxies and Their Evolution

Abstract: We propose to investigate the evolution of ellipticals out to redshift 1.0 by examining their "fundamental plane". For this purpose most of the data available in the literature goes out to z=0.5 and we plan to extend the redshift regime by gathering photometric data in the infrared (J and K bands) of ellipticals in the core of CL1603+4312 (z=0.9). Spectroscopic data for this target has been already obtained (de Carvalho etal. 2001). By putting together these data we will be able to investigate the evolution of normal ellipticals out to the look-back times of almost 2/3 of the Hubble time! This will provide strong constraints on evolution of normal elliptical galaxies in clusters and the possible redshifts of their formation.


GN-2001B-Q-30

Title: HI Selected Dwarfs: A New Class of Galaxy -or- Unreliable Distances?

Abstract: The primary aim of this proposal is to determine accurate distances to two Extreme Gas-Rich Dwarfs selected by Blind 21cm Line surveys. These two galaxies are representative of a galaxy class with an apparent large HI gas mass fraction, which may be vastly under-represented in conventional catalogs. The contribution of these galaxies to the mass content of the Universe, and hence their cosmological significance, rests upon the accurate calculation of their number density. The determination of this is complicated by the fact that they can only be detected at nearby distances, where peculiar velocities with respect to the Hubble flow make it difficult to obtain precise distance determinations from a redshift; this uncertainty propagates into the computation of volume density. Thus it is necessary to find an independent distance estimator for at least a sub-sample of these galaxies. In this case their proximity helps us, because using a large aperture telescope like Gemini means that we can resolve the bright stellar population and determine their distances using the tip of the red giant branch in a Colour-Magnitude diagram. We can also use these Colour-Magnitude diagrams to study the recent star-formation properties and the reddening towards these galaxies, and see if these gas dominated galaxies have unusual star-formation properties. It is crucial to our understanding of the distribution of mass in the Universe that we verify whether or not we are looking at a new class of galaxy, and if they could contribute significantly to the mass budget of the Universe.


GN-2001B-Q-31

Title: Stellar Rotation Curves of Starbursting Dwarf Galaxies

Abstract: We propose to obtain stellar rotation curves of a small sample of starbursting dwarf galaxies to investigate kinematic constraints on evolutionary scenarios for dwarf galaxies. Our previous work on the gas kinematics of starbursting dwarf galaxies indicates that the majority of gas-rich dwarf galaxies are rotation dominated systems. However, our preliminary study of the stellar kinematics of 3 starbursting dwarf galaxies (obtained with the CTIO 4m) indicates that the stars and gas are not necessarily kinematically coupled in low mass galaxies. We now propose to expand our stellar kinematic sample using GMOS on Gemini North in long slit mode. The proposed observations will more than double the number of starbursting dwarf galaxies with independent measures of stellar and gaseous kinematics, and will provide crucial kinematic constraints for dwarf galaxy evolutionary scenarios.


GN-2001B-Q-32

Title: The youngest and most luminous Giant HII regions: a link with HII galaxies

Abstract: For a very long time, HII regions have been associated with recent star formation. The brightest subset of these, also known as Giant HII regions are expected to be nesting the formation of massive stars at very large rates, hence their denomination as starburst regions.One of the outstanding properties of these regions is their supersonic observed linewidth. Furthermore this supersonic width correlates well with its linear diameter and the overall luminosity emitted in that line and this correlation seems to hold for HII Galaxies, that can be traced to z~3 and used as distance indicators.

In a recent research project, we have re-analysed the observed correlation for Giant HII regions in order to establish the zero-point of the regression, essential for the extension to cosmological distances. Accurate emission line photometry showed that evolutionary effects introduce a large scatter in the regression and we found that the brightest knots of three GHRs in M101 seem to follow the regression at the high luminosity end, in the range of the lower luminosity HII Galaxies. Their luminosities suggest they are up to 8 times brighter than NGC604, or 30 Doradus, although their linear sizes are quite comparable.

The following steps point towards a detailed analysis of the stellar population and interstellar matter of these amazing starburts regions. We have obtained telescope time to perform broad band JHK photometry on NGC5471 However, our major uncertainty in the determination of the absolute fluxes (luminosities) came from the impossibility to use the Balmer decrement as estimation of the extinction.


GN-2001B-Q-33

Title: Circumnuclear Structures in the Interacting Seyfert Galaxy NGC 1241. II.- Spectroscopy.

Abstract: High resolution Gemini North Telescope K, J images and HST Pa alpha and (V+R) images were used to study the spiral pattern in the inner 6.5" in NGC 1241, an interacting galaxy with active nucleus. The morphologycal scenario is complex and the structural parameters are different in each band. IR emission unveils the presence of a clumpy star forming ring, with mean diameter ~1400 pc and a N-S aligned ~500 pc long, central bar. This mini-bar appears in Gemini IR data but it is not detected by the optical HST images. Ellipses fits indicate that disk inclination is similar to that of the star forming ring.

We have applied Fourier analysis of the spiral structures for the first time at circumnuclear scales, in the optical and IR bands simultaneously. Fast Fourier Transform shows that a barred m=2 mode is dominant in K and J bands. The bar in K and J bands is counterclockwise rotated by 30 with regard to the Pa alpha one. (V+R) band presents a more complex structure with a strong m=1 mode. The position of the m=2 mode corotation is clearly defined by our analysis and approximately coincides with the extreme of the Pa alpha bar. The pattern angular speed is Omega_p=230+-20 km/sec/kpc. A rough estimate indicates a pattern age of the order of tens of millions years. There is also a leading spiral pattern (with a sense of rotation opposite than the main spiral arms) which ends in the Pa alpha ring. We have studied the rotation curve of the central 10 kpc (~ 40") of NGC 1241 obtaining 50 radial velocity measurements in three different position angles. These observations indicate a large velocity gradient of 70 km/sec/arcsec in the central 5 arcsec. The fitting of different density distribution laws to the derived rotation curve indicates a mass of ~9x10^9 Ms in the inner kpc. Both spiral patterns would be decoupled from the global one extending beyond the main bar: as in other cases studied by us, the ring seems to be inside an Inner Lindblad Resonance and the Lindblad curve Omega-kappa/2 for NGC 1241 begins to drop for Rmax=400 pc (~1.5"), but the limited spatial resolution does not allow us to find out a definitive evidence for the existence of a second ILR inside at inner radii. Up to date there is no published morphological or kinematical evidence for the presence of a second ILR at such small radii, a necessary ingredient for the presence of circumnuclear ring of star formation, considering the results of recent hydrodynamic simulations. IR spectroscopic data with high spatial resolution would be the ideal complement to our Gemini and HST images, and would allow us to complete the study of the stellar population and establish realistic mass models of the matter traced by starlight in this complex region. NIRI spectroscopy would allow us to extend the rotation curve to the inner 2 arcsec, with a spatial resolution of 0.3 arcsec (~75pc), in order to probe the core mass distribution and to resolve the behavior of the curve Omega-kappa/2. Spectroscopy at different position angles could also help us to confirm the presence of a strong bar inflow as feeding mechanism for this active nucleus. Note: Te first results of this program have been submitted to The Astrophysical Journal and will be presented in the International Workshop "The Central Kpc of Starbursts and AGNs", to be held at La Palma (May 2001).


GN-2001B-Q-34

Title: The first galaxies in the Universe

Abstract: We propose to use NIRI to observe regions of high magnification of the gravitational lens associated with the rich massive cluster Abell 370. Our targets are the putative Population "B" proto-galaxies at z ~ 9. Deep integrations in good seeing conditions with Gemini, coupled with the amplifying effects of the cluster, should enable us to detect, or at least set constraints on, this primordial population which is believed to have been responsible for the initial re-ionization of the intergalactic medium and the enrichment of the Lyman alpha forest clouds. Long, 5hour, integrations in J and K in excellent conditions will be required to achieve the required depth. The wide field mode of NIRI will allow us to observe the whole Einstein Ring region at once. The observations will also yield a very deep cluster luminosity function and several lensed images of galaxies at less extreme redshifts.


GN-2001B-Q-35

Title: Spectroscopy of OB Stars in the Giant HII Region W49A

Abstract: We propose to collect K-band spectra from a group of candidate OB stars in the Giant HII Region W49A. The spectral classification will enable the determination of an accurate distance to this obscured HII region, an important piece to trace the spiral structure of our Galaxy. This set of data also is the starting point to assess the parameters of the stellar cluster, such as the initial mass function, stellar density and ionizing sources of the HII region.


GN-2001B-Q-36

Title: Near-IR characterization of the intermediate age clusters of NGC 1275.

Abstract: The central galaxy in the Perseus cluster, NGC~1275, displays a spectacular array of galactic phenomena, including an AGN, radio lobes, evidence for mergers, a huge (~ 10^{10} M_sun) and unsettled molecular gas mass, a complex cooling flow, and recent star formation (SF; Conselice, Gallagher, \& Wyse 2001). Due to the surrounding intracluster medium, SF in NGC~1275 occurs under high pressure, theoretically favoring SF in dense star clusters (Elmegreen \& Efremov 1997). Optical studies reveal >10^3 clusters, about 1/3 being younger than ~0.5Gyr. We request use of Gemini with NIRI for a sensitive IR study of these unique objects. Goals from imaging include a complete census of brighter clusters with minimal obscuration to produce a luminosity function, age/metallicity analysis from colors, and a full view of the tidal distortions and SF processes in the main galaxy body. Spectroscopy of the brightest cluster, H1, will be analyzed through a comparison with a similar cluster, W3, observed in the merger NGC7252, and fitting by Strasbourg IR spectral synthesis models. From this we will confirm the cluster age, ascertain if the AGB is O-rich or C-rich and thereby constrain the metallicity, and build a basis for interpreting JHK_s colors of the photometric sample. The results will be compared with similar studies for star clusters formed in interactions exempt of the rigors of a galaxy cluster core (e.g. NGC7252 or the Antennae).


GN-2001B-Q-37

Title: CO in T-type (CH4-dominated) brown dwarfs

Abstract: T-type or "methane" dwarfs are brown dwarfs whose photospheres are sufficiently cool that almost all carbon is incorporated in methane rather than in carbon monoxide. In chemical equilibrium the fraction of carbon in CH4 would be virtually 100 percent in the photospheres of objects as cool as the prototypical T dwarf, Gliese 229B. However, M-band spectra of Gl 229B show a much larger (although inaccurately known) abundance of CO than predicted for chemical equilibrium. The reason for this difference is unknown, but it is suspected that upwelling of deeper hotter layers, where CO is more abundant is responsible. We propose to obtain M band spectra of three additional T-type dwarfs and an improved spectrum of Gl229B, covering a wide range of effective temperatures in order to begin to explore whether the overabundance of CO is a common phenomenon. The results will begin to reveal similarities, differences, or patterns in brown dwarf atmospheric structure and evolution and could also have important implications for abundances in giant planets and their stellar primaries.


GN-2001B-Q-38

Title: Star Formation History of IZw18 \& SBS0335--052E

Abstract: We intend to obtain very deep optical spectroscopy (Gemini North+GMOS) of the underlying stellar population already detected in the extremely metal-poor Blue Compact Dwarf galaxies I~Zw~18 and SBS0335--052E.

We will measure the D4000, H(beta) and Mg_2 spectroscopic indexes for this stellar population and the results will be compared with the predictions of evolutionary synthesis models. This analysis will allow us to discriminate between the different scenarios proposed for the evolution of these two galaxies, definitively confirming or ruling out their nature as truly young systems. Our conclusions will not be limited by the distance, nebular-emission contribution, and/or dust-extinction uncertainties commonly associated with previous studies on these objects.

Due to the low surface brightness of this stellar component (24.5-26 mag/arcsec^2) and the signal-to-noise ratios required to reach our scientific objectives (snr>1 for D4000, >4 for H(beta), and >5 for Mg_2 per Angstrom) the use of a 8-m class telescope like the Gemini North is required.


GN-2001B-Q-39

Title: The evolution of high-redshift quasar host galaxies

Abstract: It is now apparent that most nearby massive spheroids harbour a black hole of proportionate mass. Consequently, black-hole and spheroid formation/growth are recognised as intimately-related processes, with the evolution of quasar host galaxies as a function of redshift now seen as a key measurement in observational cosmology. Using NICMOS on HST we have recently discovered signs that the properties of quasar hosts are beginning to change by z=2. We therefore propose to use NIRI on Gemini to extend our study of quasar hosts through the crucial cosmic epoch z=2 to z=4. If the trends seen at z~2 continue to still higher redshift then it is clear that current CDM-based models of structure formation can be rejected. This project exploits the capabilities of Gemini+NIRI to the full, as we require both excellent image quality and the ability (impossible with NICMOS) to detect low-surface brightness emission at K.


GN-2001B-Q-4

Title: The dust-enshrouded formation of massive elliptical galaxies

Abstract: We propose deep NIRI K-band imaging of the 12 brightest sub-mm sources (S_{850} > 8 mJy) detected in our major SCUBA/JCMT surveys. These sub-mm sources have inferred dust-enshrouded star-formation rates >1000 solar masses/yr, as required for the formation of the most massive elliptical galaxies in ~1 Gyr, and are sufficiently numerous to potentially account for the formation of all present-day massive (>4L*) ellipticals. Determining their nature/redshifts is now of fundamental importance for understanding galaxy/structure formation. Finding unambiguous IDs for these sources requires high-accuracy positions (from IRAM PdB or VLA follow-up already underway) combined with very deep infrared imaging. Our one existing deep (6 hrs with UKIRT) K-band identification has K=21-22, and a complex IR morphology reminscent of radio galaxies at z=3-4, offering a first clue that the high-z formation epoch inferred for radio galaxies may apply to massive spheroids in general. Deep NIRI observations represent a crucial step towards settling this issue.


GN-2001B-Q-40

Title: A Study of the Metallicity Dependence of the Cepheid Period-Luminosity Relation in M33

Abstract: We propose to use one night of WIYN+MiMo and half a night of Gemini+NIRI time to study the metallicity dependence of the Cepheid Period-Luminosity relation, one of the leading systematic uncertainties in the extragalactic distance scale.

We have recently completed a survey for variable stars in M33, covering an area of 1200 \sq \arcmin. Thus far, we have discovered over 400 Cepheids that span a range in galactocentric distances of more than 4~kpc. The abundance gradient of M33 is one of the largest among nearby spirals, and its size is 0.8~dex over our survey area. This makes our sample of variables ideally suited for a study of the metallicity dependence of the Cepheid Period-Luminosity relation.

We propose to obtain a data set of unprecedented photometric quality and wavelength coverage, with modest phase coverage, to study this effect. Thanks to our existing knowledge of the positions and periods of the variables, only a minimal amount of telescope time is required. The proposed observations will result in a highly accurate and precise characterization of the metallicity dependence of the Cepheid Period-Luminosity relation across the optical and near-infrared, sensitive to any values of this effect that would be of importance for the Extragalactic Distance Scale. Additionally, our study will yield a detailed characterization of the extinction law of M33, and our photometry database will be of great use to the community for studies of stellar populations.


GN-2001B-Q-41

Title: The Chemistry of the Extreme Outer Disks of Nearby Spiral Galaxies

Abstract: The history of the chemical enrichment of the outer disks of galaxies is poorly known, despite its importance for understanding the chemical evolution of the universe through lines of sight to distant objects. Is the metal content of the peripheries of disks the result of a slow continuous star formation process, or have external parts been contaminated primordially by the metals expulsed from the massive starbursts during halo/bulge formation? Internal disk dynamics may have historically been even more important, especially if strong radial flows were induced by bars. We propose to use GMOS to measure O/H abundances of the faint HII region populations in the outer disks (R>R_25) of two spiral galaxies, one normal (NGC 628) and the other barred (NGC 925) to establish the chemical state of the extreme outer regions of galaxy disks in the light of the predictions for the above processes. The primordial pollution scenario predicts a flattening (or even increasing) gradient in the very outer part, while the bar scenario would produce a rather flat distribution in the inner disk, but thereafter a very steep negative gradient in the most outer parts of the disk.

The equivalent of 1 night is requested from the Canadian TAC and 1 night from the Gemini TAC.


GN-2001B-Q-42

Title: Clustering of Galaxy Clusters at Intermediate Redshifts

Abstract: We propose to continue a redshift survey of 141 objectively selected galaxy clusters to measure their clustering properties and constrain models of the formation of structure in the universe. This is the first redshift survey to probe cluster correlations on comoving scales of ~50h_{75}^{-1} Mpc at z ~ 0.5 and will thus provide an original and important constraint on the evolution of large-scale structure. The cluster sample comes from our deep (I_AB < 24), contiguous 16 deg^2 I-band KPNO 4-m survey. The proposed observations distinguish themselves from other ongoing distant cluster redshift work in that this survey will be able to provide meaningful constraints on the large-scale spatial distribution of moderate redshift clusters owing to the large angular area and contiguous geometry of the parent survey. The availability of GMOS provides a highly efficient solution to the acquisition of redshifts for the 100 cluster candidates with 0.5 < z_est < 0.7. The systems with z_est > 0.6 are needed to assure complete sampling of the cluster population at z_obs ~ 0.5. The observational strategy is extremely well-suited to the initial capabilities and queue observing mode of Gemini. Interim projects which are being executed during the course of the survey include homogeneous studies of intermediate $z$ brightest cluster galaxies, the space densities of clusters and superclusters, and cross-correlations with existing VLA 20 cm data. This survey began using the KPNO 4m to obtain redshifts for the 0.3 < z_est < 0.5 sample. We have completed this phase of the program and have observed 41 clusters. We have discovered at least 2 superclusters at z = 0.23 and z = 0.50.


GN-2001B-Q-43

Title: Redshift, velocity structure and starburst activity of a forming ultramassive cluster

Abstract: Theories predict that the hierarchichal build up of ultramassive structures like rich clusters include dramatic periods of cluster-wide AGN/starburst activity as massive velocity-separated sub-clusters merge. Using new techniques (the TexOx Cluster Survey with Sunyaev-Zeldovich follow-up) we have recently discovered a system which seems to be the first concrete example of a structure observed during one of these periods. We need basic information on this, as yet unique, system: namely, its redshift, its velocity structure (two sub-clumps separated by ~2000 km/s would be in line with theory), and the spatial distribution of passive, post-starburst and active star-forming systems throughout the structure. GMOS on GEMINI can deliver this information in a way ideally suited to early shared-risks observations with this instrument.


GN-2001B-Q-44

Title: The Formation History of NGC 3115

Abstract: We propose to measure age and metallicity gradients in the bulge of the nearby S0 galaxy NGC 3115 using ultra-deep long-slit spectroscopy with GMOS. The data, extending out to at least twice the half light radius (2xR_e=200"), will allow us to compare integrated line strengths of the bulge light with those of the globular cluster population at the same radius. We have recently obtained high S/N spectroscopy of the globular clusters around NGC 3115 using FORS-2 on the VLT. The observations proposed here will enable us to determine whether the formation history of the luminous bulge is consistent with the two major epochs of star formation which characterize the halo cluster population.


GN-2001B-Q-45

Title: The nature of distant radio galaxies

Abstract: We propose to investigate the nature of the emitting gas and continuum of the radio galaxy PMN J0214-1158 (z=2.336) as a first step in the study of the hosts of high redshift radio galaxies (HZRGs). Redshifts larger than 2 correspond to look-back times of more than 80% of the Hubble time, at approximately the epoch of galaxy formation, and to the peak of the Quasar activity. Recent findings indicate that the formation of supermassive black-holes is strongly linked to the formation of massive galactic bulges. This link can be investigated via the study of the rest-frame optical spectra of HZRGs, which are Quasars with a hidden nuclear source in the unified scenario, and thought to be the progenitors of giant elliptical galaxies. We propose to obtain near-infrared long-slit spectra of the above galaxy using NIRI grisms in the J, H and K-bands, which will cover the rest-frame near-UV and optical regions of the spectra to: (1) use the emission-line fluxes to investigate the nature of the ionizing source and calculate the contribution of recent star-formation to the energetics of the nuclei; (2) use the continuum slope and absorption features to investigate the nature of the stellar population and other possible sources of continuum emission through spectral synthesis techniques.


GN-2001B-Q-46

Title: A GEMINI investigation of the history of energy production in the universe

Abstract: The deep SCUBA surveys by ourselves and others have significantly changed our understanding of the early universe, revealing a population of very luminous objects at high redshift that emit a substantial fraction of the bolometric energy of the universe. We are proposing to use NIRI to obtain spectra of 3 of our secure identifications in our 3-hour field and planning to continue this project with objects in our 14-hour field next semester. These observations will lead us to a much improved understanding of the role of these objects in the formation and early evolution of galaxies by (i) providing spectroscopic calibration for the empirical redshift estimators used for the majority of the sample and (ii) increasing the number of spectroscopic redshifts thereby constraining the redshift distribution of these objects.


GN-2001B-Q-47

Title: Microarcsecond Imaging of a Gravitationally Lensed QSO: 2237+0305

Abstract: The microarcsecond scale structure of the central region of the gravitationally lensed quasar, 2237+0305, can be determined from its wavelength dependent lightcurve. We are currently monitoring the QSO in the optical at regular intervals, and wish to extend the monitoring to infrared wavelengths. We will monitor in J, H, K, L, and M bands, and then compare the lightcurves to microlensing models to determine the size as a function of wavelength. Combined with data we will collect in the ultraviolet with HST and in the X-ray with Chandra, we will have an unprecedented view of the quasar continuum structure, providing strong constraints on black hole and accretion disk models.


GN-2001B-Q-48

Title: Imaging the evolving dust cloud from WR140

Abstract: We propose tracking by high-resolution, multi-colour infrared imaging the dust cloud due to be emitted asymmetrically by the Wolf-Rayet system WR140 in 2001.2. We wish to measure the expansion and proper motion of the cloud and relate this to the colliding-wind structure (known from radio and X-ray studies) believed to provide conditions required for dust condensation and study the temperature and density gradients in the dust cloud to determine the properties of the dust. We seek images in three narrow-band filters at one epoch in Semester 2001B and we will apply for another such observation in each of the next four semesters.


GN-2001B-Q-49

Title: Spectroscopy of radio-selected groups of galaxies

Abstract: We seek time with GMOS-1 for spectroscopy of galaxies in radio-selected groups. These are poor groups selected without optical bias which we will use to study the environmental dependence of galaxy evolution. We have carried out a large programme of photometry which has shown that the Butcher-Oemler effect is dependent on environment. We now seek to determine the true group members and carry out a census of star-formation activity using our HST imagery to provide morphological information. We show that the programme is technically feasible with this instrumentation although it has proven to be out of reach with existing 4m telescopes.


GN-2001B-Q-5

Title: K-band Imaging of Globular Clusters in Young and Old Ellipticals

Abstract: Much has been learned about Globular Clusters (GCs) and their host galaxies from optical studies by the Hubble Space Telescope, e.g., the presence of bimodal GC color distributions in many early-type galaxies. The properties of these GC sub-populations constrain both the formation processes of the GCs and the star formation history of the host galaxies. NIRI K-band photometry of globular clusters around selected early-type galaxies will be combined with existing HST WFPC2 optical photometry (the latter has provided bona fide GC candidates already). (V-K) colors efficiently break the age-metallicity degeneracy present in optical colors. We will obtain reliable metallicities for large samples of globular clusters in both old ``normal'' ellipticals and younger merger remnants, well beyond the reach of any spectroscopic study. This will allow us to determine the chemical properties of the globular cluster sub-populations in these galaxies, to investigate their origins, and strongly constrain galaxy formation scenarios.


GN-2001B-Q-50

Title: Young Jupiters in the Orion Molecular Cloud

Abstract: We wish to obtain extremely deep NIRI images towards one field in the Orion star formation region using narrow band methane (CH4) 1.58um and 1.69um H band filters. Using this data, we will search for young, very low mass CH4 brown (T-) dwarfs/free-floating exo-planets. Since methane is present only in very cool photosphere/atmospheres (Teff below 1300K), only these objects will show large brightness differences (up to 2 magnitudes) over such a small wavelength range. These data will allow us to detect young T-dwarfs of age 10^6 to 10^7 years with masses in the range 1-7MJup within the Orion Trapezium cluster star formation region at 500pc.


GN-2001B-Q-51

Title: NIRI Imaging of the brightest sub-mm objects in the HDF and Flanking Fields

Abstract: We propose using NIRI to image a region in the HDF flanking fields where SCUBA observations have revealed three very bright sub-mm sources. Previous studies indicate a correlation between these type of sources and faint red (K~22, I-K~ 6) galaxies. NIRI's field of view is comparable to the size of the region containing the sources, and the resolution and depth obtainable with Gemini/NIRI should allow us to identify the near-IR galaxies associated with the sub-mm emission. Targets for future spectroscopy can then be selected in order to pin down their redshifts.


GN-2001B-Q-52

Title: Spectroscopic Confirmation of z~1 Galaxy Clusters.

Abstract: Redshift ~1 clusters of galaxies are powerful probes of cluster and galaxy evolution. Their galaxies' stellar populations provide important constraints on the star-formation history in proto-clusters, and their dynamical masses provide fundamental insight into the growth of large scale structure.

In recent years a number of candidate galaxy clusters z~1 have been put forward. However, the candidates in the literature form a very heterogenous set: being selected mainly on the basis of galaxy overdensities around high-z radio galaxies/ quasars, or the presence of extended X-ray emission. Spectroscopic confirmation only exists for only 3 of these systems, with few member galaxies.

We have undertaken a survey for z~1 clusters using NIR colour selection. Our sample is thus homogenous, and the selection function is readily quantifiable. We request GMOS spectroscopy to identify cluster members for 2 high-significance cluster candidates, thus adding significantly to the current spectroscopic sample (both in terms of number of clusters, and in the number of member galaxies), and allowing many follow-up projects to be undertaken with our extensive photometric data.


GN-2001B-Q-53

Title: The Extended Star Formation Histories of M81 Group Dwarf Elliptical Galaxies

Abstract: We propose to use NIRI J and K band observations to survey five M81 group dwarf elliptical (dE) galaxies for upper asymptotic giant branch (AGB) stars. Such stars are an indicator of the presence of intermediate-age (2 $\lesssim$ age $\lesssim$ 10 Gyr) populations. Our HST/WFPC2 study (in the V and I bands; Caldwell et al., 1998, AJ, 115, 535) has revealed the presence of significant numbers of upper-AGB stars in two M81 group dEs, and we wish to establish if this is a common occurrence by studying other dE members of this group. Near-IR band photometry is required to determine bolometric magnitudes, and therefore age estimates, for any upper-AGB stars found. Our results will provide information on the extended epochs of star formation (if any) in these dwarf ellipticals and will be directly comparable to existing information for Local Group dEs, such as the dwarf companions to the Galaxy and to M31. In this way we will add to the understanding of the factors, which include environment, that govern the star formation history of these galaxies.


GN-2001B-Q-54

Title: Imaging the stellar hosts of microJansky radio sources

Abstract: Among the most controversial problems in studies of the evolution of galaxies are the effects of dust obscuration on the selection and interpretation of star-forming galaxies at intermediate redshifts. The UV light from such galaxies is dominated by the least-obscured star-forming regions, while increasingly longer wavelengths (Halpha/far-IR/radio) are dominated by increasingly more obscured components. It is therefore not surprising that recent far-IR and sub-mm surveys have revealed that the most vigorous sites of star formation are obscured by dust. This poses very serious problems to in any attempt to infer the history of star formation from observations made at UV or optical wavelengths.

To address this problem we propose to use high angular resolution K-band NIRI imaging of radio-selected star-forming galaxies to carry out the first-ever study of the mass assembly rate in obscured galaxies with high star-formation rates at intermediate redshifts. This study is of fundamental importance as it is likely that many, and perhaps all, large galaxies will have passed through this phase during some stage of their formation.


GN-2001B-Q-55

Title: Comparing the Stellar and Gas Phase Metallicities in Nearby Dwarf Irregular Galaxies

Abstract: We propose to use the strength of 2.3 micron CO absorption in bright red giant branch stars to estimate the mean global metallicities (i.e. [M/H], as opposed to single-element values such as [Fe/H], [O/H], etc.) of stars in the nearby isolated dwarf irregular galaxies SagDIG and Pegasus. These galaxies have gas phase metallicities determined from HII regions, and with the proposed observations it will be possible to compare the stellar and gas phase metallicities. We will thus gain insight into the chemical evolution of these systems. In particular, if the gas phase metallicity, which is derived from observations of species such as oxygen that are formed mainly in SN II, differs significantly from the global metallicity, which will be derived here, then the chemical enrichment history must have been episodic, involving rapid bursts of star formation. However, if the gas and stellar metallicities are similar then a slow enrichment history is implied. The results from this study will also provide a means of calibrating the global metallicities of more distant systems, where individual stars can not be resolved, and the chemical composition is infered by necessity from emission line spectra. Finally, these data will also be used to investigate the AGB content of these systems, and thereby probe their star-forming histories during intermediate epochs.


GN-2001B-Q-56

Title: Testing the evolution of low luminosity, early-type galaxies in A963 at z=0.2

Abstract: Observations of galaxies in clusters out to z~1 show conflicting signatures of evolution: with an increasing in the number of S0 galaxies at lower redshifts, but little sign of previous activity in their stellar populations (at least for ~L* galaxies). We propose high S/N spectroscopy of ~80 early-type galaxies in a well-studied rich cluster at z~0.2 reaching down to 0.25L*. Combining these new data with our existing HST imaging we will disentangle the enigmatic processes which drive the morphological evolution of disk galaxies in rich clusters and produce the morphology-density relation seen at the present day. The main goal of the project is to measure high precision line-strengths indices for galaxies as faint as 0.25L* (twice as faint as has been done previously). These will be used to construct accurate age-metallicity diagnostic diagrams to compare the star formation histories of E and S0 galaxies across a broad luminosity range.


GN-2001B-Q-57

Title: A GEMINI investigation of the history of energy production in the universe

Abstract: The contribution the faint SCUBA sources make to the extragalactic background radiation shows that about 25% of the energy emitted by galaxies since the big bang has come from this population of luminous dusty galaxies. However, only a few percent of the sources have spectroscopic redshifts and estimates of the median redshift of the population vary between 2 and 3, making the implications for galaxy evolution unclear. If, for example, the SCUBA sources are young ellipticals, the redshift uncertainty makes it equally plausible that the ellipticals formed from the collapse of individual high-redshift gas clouds or by the gradual merger of smaller systems. We propose to use NIRI to obtain spectroscopic redshifts of the nine sources in the Canada-UK Deep Submillimetre Survey with secure optical/IR counterparts and without spectroscopic redshifts. If successful, the observations will increase the number of SCUBA sources with spectroscopic redshifts to 13 in our survey, and to 17 if all surveys are considered. The contribution of dust sources to the background is heavily weighted by redshift, and so although the success of our programm would only raise the percentage of SCUBA sources with measured redshifts to 25%, it would reveal the redshift distribution of over 50% of the energy production - and, among other things, allow us to distinguish between the two models of elliptical formation.


GN-2001B-Q-58

Title: K-band Imaging of Globular Clusters in Young and Old Ellipticals

Abstract: Much has been learned about Globular Clusters (GCs) and their host galaxies from optical studies by the Hubble Space Telescope, e.g., the presence of bimodal GC color distributions in many early-type galaxies. The properties of these GC sub-populations constrain both the formation processes of the GCs and the star formation history of the host galaxies. NIRI K-band photometry of globular clusters around selected early-type galaxies will be combined with existing HST WFPC2 optical photometry (the latter has provided bona fide GC candidates already). (V-K) colors efficiently break the age-metallicity degeneracy present in optical colors. We will obtain reliable metallicities for large samples of globular clusters in both old ``normal'' ellipticals and younger merger remnants, well beyond the reach of any spectroscopic study. This will allow us to determine the chemical properties of the globular cluster sub-populations in these galaxies, to investigate their origins, and strongly constrain galaxy formation scenarios.


GN-2001B-Q-59

Title: NIR spectroscopy of trans-neptunian objects, centaurs, and cometary nuclei

Abstract: Tras-neptunian objects (TNOs), Centaurs, and Jupiter family comets (JF) are different but closely related populations of icy minor planets. They are remnant planetesimals from the early stages of the formation of the solar system, and probably contain some of the least modified materials remaining from the protosolar nebula. The information provided of these objects by NIR spectra is fundamental for the understanding of the surface composition and evolution, allowing the detection of water ice and other more complex molecules, and will allow us to study the processes that modify their surfaces (irradiation, collisions, cometary activity), and to study the physical inter-relationship between the three populations.


GN-2001B-Q-6

Title: Multi-Filter High-Resolution Imaging Observations of a Unique Sample of Strong-Lensing Clusters

Abstract: We propose multi-filter high-resolution imaging of four new strong-lensing clusters recently discovered by the Red-Sequence Cluster Survey (RCS). The four clusters span 0.3<z<0.8, with sources at 1.5<z<5, and represent a unique sample compared to the lower redshift strong-lensing clusters studied to date. The lensed sources are also extremely bright. This multi-filter imaging is a component of a larger study involving Keck, HST, Chandra, and Magellan, and will provide unique data on the star-formation history of individual galaxies at z>1.5, as well as detailed information on the mass and galaxy distribution in the clusters.


GN-2001B-Q-60

Title: Probing the high redshift Universe via quasars with z>5

Abstract: GMOS will be used to obtain identification spectra of redshift 5-7 quasars for a project whose ultimate goals are: (1) To establish the contribution of AGN to the integrated extragalactic ultraviolet background light at the highest possible redshifts. (2) To establish unambiguously the rate of decline in the space density of quasars out to a redshift of about 6.5 via the explicit detection of the characteristic `knee' in the quasar luminosity function ; (3) To determine the epoch of reionization via the Gunn-Peterson test; (4) To identify a sample of z>5 damped Lyman alpha absorbers

The quasar candidates have been robustly selected from our recent deep imaging survey at CFHT, a survey that goes more than two magnitudes fainter than the Sloan survey and hence includes quasars well below the bright end of the QSO luminosity function.


GN-2001B-Q-61

Title: The galaxy environment of z=2 QSOs

Abstract: We propose to obtain spectra of galaxies in the vicinity of two z~2 QSOs: one radio-loud and one radio-quiet. The galaxies have been imaged with the HST and have known magnitudes and positions. The companions are different in the two environments in a way that appears to be typical of the RL/RQ dichotomy: the RLQ has large and irregular companions and the RQQ has fainter and more compact companions. The galaxies are considered to be likely companions by their concentration about the QSO. Spectroscopy will indicate a) the true distribution of companions at the QSO redshift; b) the stellar populations in these galaxies; and c) the dynamics of the galaxy groups which will predict their subsequent evolution by merging or dispersal.


GN-2001B-Q-62

Title: Using IR Surface Brightness Fluctuations to Measure the Peculiar Velocity of the Perseus Cluster and the Stellar Content of its Galaxies

Abstract: Infrared surface brightness fluctuations (SBFs) have proven to be both an accurate distance indicator and a powerful tool for probing the properties of unresolved stellar populations of early-type galaxies. We have calibrated the technique and used it to measure distances to and the spread in ages of galaxies in the local universe. We propose to use NIRI to collect K' SBF data for a sample of nine galaxies near the center of the Perseus cluster to (1) better understand the history of star formation in galaxies in rich environments, and (2) accurately determine the distance to the Perseus cluster to determine its peculiar velocity. The proposed data set will provide an important independent check on galaxy age measurements that use the age-sensitive H-beta line index, which is used in conjunction with the metallicity-sensitive Mg2 and <Fe> indices. IR SBF measurements will also help reveal the extent of large-scale motions in the local universe that seem to be centered on the alleged "Great Attractor." This unique data set will be a key part of a significant collection of existing optical and infrared imaging and spectroscopic data that will be used to address a number of important questions pertaining to this complex region.


GN-2001B-Q-63

Title: Determination of the Initial Mass Function in Young Star Clusters through Infrared Photometry

Abstract: The goal of this project is the photometric study (J,H,K,L',Kcont,Hcont) of four stellar clusters still embedded in their parental cloud. The initial mass function (IMF) of the clusters will be determined and compared to test its variability with respect to environmental parameters. The originality of this proposal lies in (1) obtaining a complete sample down to 0.08 Mo and (2) studying four well separated clusters born in the same molecular cloud.


GN-2001B-Q-64

Title: The evolution of high-redshift quasar host galaxies

Abstract: It is now apparent that most nearby massive spheroids harbour a black hole of proportionate mass. Consequently, black-hole and spheroid formation/growth are recognised as intimately-related processes, with the evolution of quasar host galaxies as a function of redshift now seen as a key measurement in observational cosmology. Using NICMOS on HST we have recently discovered signs that the properties of quasar hosts are beginning to change by z=2. We therefore propose to use NIRI on Gemini to extend our study of quasar hosts through the crucial cosmic epoch z=2 to z=4. If the trends seen at z~2 continue to still higher redshift then it is clear that current CDM-based models of structure formation can be rejected. This project exploits the capabilities of Gemini+NIRI to the full, as we require both excellent image quality and the ability (impossible with NICMOS) to detect low-surface brightness emission at K.


GN-2001B-Q-65

Title: Galaxy Evolution and the Micro-Jy Radio Population

Abstract: We propose deep MOS spectroscopy with GMOS of an unique sample of ultra-faint radio sources selected from the deepest 1.4-GHz VLA map ever taken. This sample is the basis of an on-going program to exploit sensitive radio observations as a dust-independent tracer of the evolution of star formation and AGN activity in galaxies at z=0-4. The proposed GMOS observations will provide essential confirmation of the reliability of photometric redshift techniques for faint (perhaps very dusty) radio galaxies and most importantly will allow us to gauge the proportions of AGN- and star-formation-dominated systems as a function of radio flux down to flux limits of ~15 microJy. This is crucial for attempts to derive the evolution of star formation density for this population.


GN-2001B-Q-66

Title: Signposts of Star Formation in a Cluster of Submillimetre Continuum Cores

Abstract: We propose to obtain images of a newly detected cluster of submillimetre cores in the v=1-0 S(1) line of H2 and in the nearby 2-micron continuum. Shocked H2 in the form of jets or HH knots will demonstrate the presence of outflows. Continuum sources will indicate the presence of embedded YSOs. These data will help us to determine the evolutionary state of individual cores and to assess the star formation efficiency in this region.


GN-2001B-Q-67

Title: Evolution of the Host Galaxies of Low-Power AGN

Abstract: Through our Cycle 6 HST snapshot survey of BL Lac objects we have definitively characterized their luminosities and morphologies at low redshift. Intriguingly, the hosts of these intrinsically (and typical) radio-loud, low-luminosity AGN are as massive as those of AGN many orders of magnitude more powerful. At higher redshifts, studies of host galaxies have been largely restricted to these highly luminous AGN. BL Lacs, with their high beaming factors, offer an opportunity to track lower-luminosity AGN to similarly high redshifts, and so measure the differential evolution of their host galaxies. The Gemini North telescope, with its excellent seeing and superior light collecting power, offers a unique opportunity to take our HST study this step further.


GN-2001B-Q-68

Title: Interactions among YSOs and Dense Clumps in MSX Infrared-Dark Clouds

Abstract: We propose to use the NIRI imaging camera to observe several of the bright, compact sources identified in our SCUBA maps that seem to be associated with YSOs visible in the MSX images and in Ks images from the 2MASS survey. Relatively short integrations with NIRI should be sufficient to show whether the YSOs are interacting with the dense clumps seen in the SCUBA images. Photometry of the YSOs will help define their SEDs so that we can determine their temperatures, luminosities and masses.


GN-2001B-Q-69

Title: Search for infrared emission from Anomalous X-ray Pulsars (AXPs) associated with supernova remnants (SNRs)

Abstract: The anomalous X-ray pulsars (AXPs) represent a growing class of compact objects discovered at X-ray energies whose nature remains a mystery. Unlike the Crab-like pulsars, they are radio-quiet, slow X-ray rotators, and characterized by an X-ray luminosity generally higher than their rotational spin-down energy. Models proposed to explain their anomalous nature invoke accretion from a low-mass companion or a disk, or an ultra-magnetized neutron star (a magnetar). A deep search for their counterparts in the optical and infrared should shed light on clarifying their nature. Here, we propose to observe with the Gemini telescope three AXPs found inside supernova remnants.


GN-2001B-Q-7

Title: Multi-Filter High-Resolution Imaging Observations of a Unique Sample of Strong-Lensing Clusters

Abstract: We propose multi-filter high-resolution imaging of four new strong-lensing clusters recently discovered by the Red-Sequence Cluster Survey (RCS). The four clusters span 0.3<z<0.8, with sources at 1.5<z<5, and represent a unique sample compared to the lower redshift strong-lensing clusters studied to date. The lensed sources are also extremely bright. This multi-filter imaging is a component of a larger study involving Keck, HST, Chandra, and Magellan, and will provide unique data on the star-formation history of individual galaxies at z>1.5, as well as detailed information on the mass and galaxy distribution in the clusters.


GN-2001B-Q-70

Title: Characterization of the Extragalactic FIR Background Population

Abstract: We propose to continue our program of characterizing the population of faint far-infrared sources that have been detected at the faintest flux levels in IRAS and ISOPHOT deep fields. The observations of the ISOPHOT sources are part of our required ground-based followup program promised to NASA in return for funding to support our participation in the US-Japan Cosmology Key Program of guaranteed time observations with the ISO satellite. Two complete samples are being observed: (1) a sample of 80 ISOPHOT sources with S_175 = 20-350 mJy in two 44' 44' deep fields in the Lockman Hole (LH), and (2) a non color-selected sample of 30 intermediate redshift (0.4 < z < 0.8) ULIGs with S_100 =400-1000 mJy that were discovered in the IRAS Faint Source Database. The addition of the smaller sample of IRAS objects allows us to have a sufficient number of lower redshift objects so as to equally populate redshift bins (dz = 0.25) over the range z = 0 - 1.5. Our primary focus this semester is on obtaining redshifts and line diagnostics for the fainter half of the ISOPHOT sources, and to continue to compile a consistent set of imaging data on the majority of the objects in both samples. The complete set of multiwavelength data include moderate-to-high dispersion optical and near-IR spectra, deep NIR imaging, submm photometry, and millimeterwave (CO) spectra. The redshift data are clearly essential for tracing the evolution of the luminosity function of luminous infrared galaxies over the important redshift range z~ 0 - 1.5 where the comoving space density of LIGs appears to increase by at nearly 2 orders of magnitude. The additional multiwavelength observations allow us to determine the properties of individual sources, to compare these intermediate-z objects with their putative local analogs (e.g. Arp220, Mrk231) and to compute the integrated contribution of LIGs to the total energy budget of the Universe. Our observations will also be extremely important for establishing a possible connection between LIGs in the local Universe and the much fainter (and much harder to observe) high-z sources (z~ 1-4) detected in SCUBA deep fields.


GN-2001B-Q-71

Title: Stellar Populations in Cluster Galaxies at Intermediate redshift

Abstract: We intend to determine the stellar population (SP) content of early-type galaxies in the cluster ZwCL0024+1654 at z=0.4, using near-infrared imaging and high resolution spectroscopy. These data will be combined with optical imaging and photometry from HST, which will provide crucial morphological information for the target sample. The photometry will also allow building color-magnitude relations which will serve as a further constraint on the SP analysis. The spectroscopic data will provide measures of internal velocity dispersion and equivalent widths of absorption line indices used in the analysis of SPs in galaxies. The analisys will employ state-of-the-art SP models, relying on a grid of high resolution synthetic spectra and broad-band colors of single SPs with a comprehensive range of ages and metallicities.


GN-2001B-Q-72

Title: Spectroscopy of High Z Galaxies and Chandra X-ray Sources

Abstract: We propose to combine the ultra-deep optical, IR and Chandra X-ray imaging in the WHDF with the light-grasp and multiplex advantage of GEMINI GMOS to attack two front-line research areas simultaneously; the search for galaxies in the range 4.5<z<7.5 to determine the epoch of galaxy formation and the spectroscopic identification of faint Chandra X-ray sources to determine the origin of the X-ray background. We shall observe 10 5<z<7 galaxy candidates detected by R dropout and a further 70 2.5<z<4.5 candidate galaxies detected by B and U dropout, together with 20 faint X-ray sources detected in a deep 75ksec Chandra observation of this same field. Finally we will simultaneously observe a sample of galaxies with K<19.5 (including all candidate ERO's in the WHDF) to detect the `missing population' of early-type galaxies at z>1.


GN-2001B-Q-73

Title: The Wolf-Rayet nebula NGC 2359: a photodissociation region or shocked molecular gas?

Abstract: We propose to obtain infrared spectra in the H and K bands of the filamentary molecular hydrogen emission from the Wolf-Rayet nebula NGC2359. Our goal is to determine the excitation mechanism for the H2 transitions, either by shocks or by ultraviolet fluorescence from the hot star. These observations will give us new insight into the origin of the HI gas in this nebula: either primordial and swept-up by the stellar wind and therefore mainly shock excited or dissociated from the nearby molecular cloud by the UV radiation from the hot star and therefore mainly fluorescent.


GN-2001B-Q-74

Title: Damped Lyman alpha Galaxies at z > 3.0

Abstract: Abstract: We propose to observe in J,H, and Ks the field around the QSO PSS0209+517, which is at a redshift of 4.18. Recent spectrocopic observation has shown three dense systems along this line of sight (<log NHI> ~ 20.2). Two of these absorbing systems are very close to each other (Delta_v ~ 130 Km/s) which could be an indication of a proto-cluster at a redshift of 3.8. Making use of a new chemodynamical model developed by Friaca and Terlevich (1998) we predicted the colors for the candidate DLA host galaxies (DLAGs) as a function of the epoch of galaxy formation, the initial baryonic mass of the spheroid, and redshift. Since we know the redshift of the three components from analyzing the Lyman-alpha forest (Keck data, Djorgovski et al. 2001), we can locate the DLAG (or DLAGs ?) in the color-color diagram defined by J,H, and Ks. The JHK photometric redshift (J-dropout) technique proposed here can become a very effective way for searching for DLAGs at very high redshift (z > 3.0).


GN-2001B-Q-75

Title: The Fundamental Plane and black hole masses of z=0.5 radio galaxies

Abstract: We are undertaking an investigation into connections between the host galaxy properties, black hole masses and radio luminosities of radio galaxies. The project has been awarded 44 orbits of WFPC2 imaging with the HST to determine the morphologies, scalelengths and surface brightness profiles of a large sample of z=0.5 radio galaxies, spanning a vast range (3 dex) of radio luminosities. In this proposal (along with one submitted for the WHT ISIS spectrograph) we plan to obtain moderate resolution, high signal-to-noise spectroscopy of the whole sample of 46 objects. This will give accurate stellar velocity dispersions, which provide the most reliable estimate of black hole masses. It will also alllow us to plot the Fundamental Plane for z=0.5 radio galaxies, investigate their mass-to-light ratios and identify which galaxies are not relaxed ellipticals.


GN-2001B-Q-8

Title: Search for Protoplanetary Disks and Giant Extrasolar Planets Around Extremely Low Mass Young Objects

Abstract: Recent deep surveys of star-forming regions have revealed an increasing number of extremely low mass members with near infrared excesses likely to originate in young protoplanetary disk material. We propose to obtain NIRI deep (Ks = 21) sub-arcsec resolution (0.05''/pix) images of six of these young (10^6 yr) stars. Our selected targets are located in the Taurus-Auriga star-forming cloud and have estimated masses close or even below the 0.08 solar masses H burning limit. We will search for circumstellar protoplanetary disks and giant extrasolar planetary companions between 7.5 and 3800 AU from the central sources. NIRI images will allow us to detect a 30 Jupiter mass companion at the distance of Taurus. Disk images will provide information on their linear extent and morphology. Binary (subsolar/substellar) detections will provide indications on the frequency of multiple systems among young objects close to or even below the 0.08 solar mass H burning limit. In addition, these observations will allow us to derive initial constraints on the potential contribution of young extremely low mass stars to the total census of planetary systems in the Galaxy. Finally, combined binaries + disk detections will provide information on the geometry of circumbinary and/or circumstellar disks and their interaction with the central star/s.


GN-2001B-Q-9

Title: Near-IR Imaging of Super Star Clusters in the Antennae

Abstract: We will use NIRI/Gemini to image the population of super star clusters in the nearest starburst merger, the Antennae. The youngest clusters are embedded in the dusty overlap region between the two nuclei, so infrared observations are essential to quantify the properties of clusters with the full range of ages and extinctions present in the system. We will measure the IR luminosity function and the age distribution of clusters across the merger, and for the brightest clusters we will combine NIRI imaging with internal velocity dispersions measured with Keck/NIRSPEC to determine the cluster M/L ratios and hence constrain their IMFs.


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Last update July 9, 2001; Phil Puxley