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Propuesta:
GS-2006B-C-2 (Conjunta con BR.)
Investigador Principal: Dra. Manuela
Zoccali (PUC)
Título:"Oxygen Abundance
in Bulge Stars"
Resumen:
The Milky Way galaxy is a Sbc
type. For this reason, there is a controvery as to
whether its bulge originated in a short phase of star
formation when the Universe was only a few Gyr old,
likewise bulges of Sa and Sb galaxies, or if its bulge
is in fact a pseudobulge, formed from the secular
evolution of the disk driven by the development of
a bar (Kormendy, J. & Kennicutt, R.C. 2004, ARA&A,
42, 603), that appears to be a dominant process in
Sc galaxies. An answer to this question can be provided
by extensive spectroscopic observations to obtain
precise element abundance ratios, such as [O/Fe] and
[Fe/H]. In the present proposal we intend to make
observations of OH lines in the H band, in order to
derive oxygen abundances, and in this way to have
a definitive measure of the oxygen abundance in bulge
stars with a range of metallicities of -0.7 < [Fe/H]
< +0.4.
Tiempo asignado: 14.5 horas
______________________________________________________________________________
Propuesta: GS-2006B-Q-8
Investigador Principal: Dr. Neil
Nagar (UdC)
Título:. "Probing The
Environment of Gamma Rays Bursts in the Era of Rapid
Followup"
Resumen: Gamma Ray Bursts
are the most luminous and transient object in the
Universe and represent the most significant new astrophysical
phenomenon since the discovery of quasars and pulsars.
In the era of rapid response followups to alerts from
new gamma-X satellites such as Swift, we propose to
acquire spectra of high redshift, short or spectrally-distorted
GRBs driven by the results of quality prompt robotic
observations performed with our fully-automated 2-m
class telescopes (which are now performing very successfully).
Our primary goals are to use the optical/IR light
from the GRB counterpart as a time-variable background
illuminating source to study the ISM in high redshift
(and intervening) galaxies, determine the physical
properties of the circum-burst medium and the burst
energetics. In the event of the discovery of an optical/IR
counterpart to a short-GRB by our robots, we propose
to activate (quick response or QR) a multicolor imaging
sequence on Gemini South (GMOS) with the goal of determining
for the first time whether the origin of (all) short
bursts is extragalactic and whether they occur in
distant galaxies. This is a continuation of our Gemini
proposal in the last semester: our proposal was accepted
and is in the queue - but not yet active. Additional
Chilean TAC time is crucial - Chilean QR programs
on Gemini are active (i.e. allowed to be triggered)
only during 10% of the semester (to reflect the Chilean
share) - so additional active time is crucial to increase
our chances of catching interesting bursts. Note that
the overall Chilean time share on Gemini is not adversely
effected by Chilean QR programs - if the program is
not activated the Chilean-allocated (but unused) time
is given back to Chile in the following semesters.
Tiempo asignado: 6 horas
____________________________________________________________________________
Propuesta: GS-2006B-Q-41 (Conjunta
con CA,US)
Investigador Principal: Dr. Dante
Minniti (PUC)
Título: "Light Echoes
from Supernovae and a Highly-Evolved Star in the Large
Magellanic Cloud"
Resumen:
The detection by the SuperMACHO
Project of moving light echoes from centuries-old
supernovae in the LMC, announced in 2005, opens up
exciting avenues of investigation linking resolved
supernova remnants with hitherto unobtainable photometric
and spectrocopic data from the outburst itself. In
this proposal, we build on the earlier success of
Rest et al, Nature, 438, 1132 (2005) and the observations
obtained with GMOS-S in semester 2005B in the following
ways: 1) We will obtain MOS spectroscopy of SN1987A
light echoes corresponding to a number of different
dust sheet "heights" out to 1 kpc in front
of the event to determine dust properties and a geometric
distance to the LMC. 2) We will obtain spectra for
a fourth ancient light echo system in the LMC, believed
to be associated with a 1000 year-old SN remnant which
had not yet been discovered when 2005B observations
were proposed and obtained, and 3) We will obtain
MOS spectroscopy of a highly-evolved late-type variable
in the LMC, apparently similar to V838 Mon, which
reveals moving light echoes in its immediate vicinity.
This star was in one of the most densely observed
MACHO Project fields and therefore a detailed lightcurve
history between 1992 and 2000 exists. The Gemini spectroscopy
will be complement proposed HST and SST observations.
We emphasize that Gemini is uniquely suited to obtain
the spectroscopy proposed herein and that the importance
of this new observational technique in testing the
limits of our understanding of all supernovae, but
especially the Type Ia SN which provide the strongest
evidence for an accelerating universe.
Tiempo asignado: 10 horas
___________________________________________________________________________________________
Propuesta: GS-2006B-C-1
Investigador Principal: Dr. Sebastián
López (U.Ch)
Título:. "GMOS-IFU
Search of Gas-rich Starforming Galaxies at z>2"
Resumen:
Damped Lyman-alpha absorption
systems (DLAs) contain roughly enough neutral gas
at redshift z = 3.5 to form the bulk of the stars
in present-day galaxies. Recent studies also suggest
that these systems contribute an equal amount of star
formation rate density at z ~ 3 as the starburst population
selected by their luminous ultraviolet fluxes. However,
little is known regarding the physical properties
of the absorbing galaxies because only a handful of
DLA galaxies at high redshifts have been firmly identified.
With this program we propose to conduct a novel search
of DLA galaxies using the Integral Field Unit (IFU)
on GMOS South. The IFU allows us to search for Ly-alpha
emission from DLA galaxies at small angular distances
to the sightline without prior knowledge of the impact
orientation of the absorbing galaxies. It serves as
a tunable narrow-band filter which, when centered
at the known DLA trough, removes the glare of the
background QSO. The IFU therefore offers a higher
efficiency than traditional imaging/spectroscopic
surveys of DLA galaxies. The scientific objectives
of the project are (1) to examine the morphologies
and impact geometry of DLA galaxies using the 2D emission-line
features reconstructed from individual IFU elements,
and (2) to obtain measurements (or upper limits) of
the star formation rates of these galaxies based on
emission-line strengths and compare with known properties
of field galaxies at the same epoch. --- Note: this
the third submission of this proposal. Last two semesters
the program has been awarded time in band 3 but has
not been executed. We are now requesting 2 nights
in classical time, which require at least one more
classical program approved to fulfill the Gemini policy
of 3-nights minimum blocks. Otherwise we would opt
for 20 hours queue mode.
Tiempo asignado: 2.0 noches
____________________________________________________________________________
Propuesta: GS-2006B-C-3
Investigador Principal: Dr. Daniel
Christlein (UCH)
Título: "Are Galaxy
Warps an Accretion Phenomenon? A Spectroscopic Perspective".
Resumen: Although warps
in the disks of galaxies have been known for decades,
their origin and evolutionary role are unclear: are
they disk material perturbed by tidal effects, or
material of extragalactic origin? A prominent hypothesis
is that they are signatures of accretion of cold gas
from the halo. In that case, they would play a critical
role in the lives of galaxies and be important to
understanding how galaxies acquire their gas. This
hypothesis can be tested by measuring the kinematics
of warps to determine whether they are corotating
at the rotational velocity of the galaxy (and thus
likely simply perturbed disk material) or lagging
behind (as would be expected of low-angular-momentum
material in the process of accretion). This test requires
kinematic measurements of gas in the outer disk with
good spatial resolution. 21-cm radio observations,
though a possible way, require enormous efforts to
simultaneously achieve good kinematic and spatial
resolution with sufficient sensitivity. Here, we propose
an alternative route: Gas at sufficiently large scale
heights in the warped outer disk I irradiated and
partially ionized by the UV flux from star formation
in the inner disk. It therefore emits H-alpha at a
surface brightness ~10^-18 erg s^-1 cm^-2 arcsec^-2.
This is well within the reach of optical spectroscopy
with GMOS-S. We propose to target 6-12 edge-on spiral
galaxies with a long-slit _offset_ from the major
axis to intercept the outer-disk warps and measure
their velocity within ~10%. Comparison to the rotational
velocity of the galaxy will then show if the warp
material is kinematically a part of the disk or not.
Kinematic measurements of accreting gas may also potentially
discriminate between traditional hot-mode accretion
and the novel cold-mode accretion model.
Tiempo asignado: 1.0 Noche
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Propuesta: GS-2006B-Q-69
Investigador Principal: Dr. Tom
Richtler (UdC)
Título:. The "star
pile" in Abell 545
Resumen: We propose to
perform a long-slit observation of the "star
pile" in Abell 545, discovered by Struble (1988).
This rich galaxy cluster hosts no dominant cD in its
center but a diffuse object of low surface brightness,
presumably an intergalactic stellar population assembled
in the deep potential well of the cluster. This will
be the first spectroscopic investigation of this apparently
"forgotten" but highly interesting object.
A low baryonic matter density permits to analyse the
dark matter profile much more accurately than it is
possible with the presence of a dominating cD galaxy.
Moreover, this object could be an ideal test object
for the controversy CDM versus Modified Newtonian
Gravity.
Tiempo asignado: 4 horas
____________________________________________________________________________
Propuesta: GS-2006B-Q-45
Investigador Principal: Dr. Luis
Campusano (UCH)
Título: "The Galaxy
Environment of a z=1.233 Quasar Lying at the Confluence
of Two Merging Clusters"
Resumen: The largest large-scale
structures (super-LSSs, SLSSs) provide essential tests
for models of structure formation and allow the very
efficient study of large numbers of galaxies, clusters
and other mass markers such as quasars. In a sky area
extending several degrees and through deep multicolor
imaging, we have found evidence for 'superposed' SLSS
>~ 20-30 Mpc at both z~0.8 and z~1.2 (Haines, Campusano
& Clowes, 2004) . The z~0.8 structure has been
spectroscopically confirmed by GMOS observations in
2005A (Soechting et al. 2006). It is in this region
that we are proposing follow-up spectroscopy over
a GMOS FOV, centered on a z~1.2 cluster (J104656.6
+054150) diagnosed to have two substructures and possibly
in the process of merging. At the confluence of these
substructures lies a z=1.233 quasar, where there is
also a band of 'red outlier' (bluer) galaxiespossibly
dusty star-forming galaxies. We plan to obtain medium
resolution spectroscopy of galaxies on this 5'x5'
field (~4x4 Mpc^2 at z=1.2) basically selected using
the criteria I-K>3.6 and K<19.5. The aims are,
to: (1) measure spectroscopic redshifts of ~30 galaxies
mostly belonging to the SLSSs at z~1.2; (2) confirm
the merging substructures of the J104656.6 +054150
cluster; and (3) characterize the environment of the
z=1.233 quasar (J104420.8 +055739).
Tiempo asignado: 15 horas
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Propuesta: GS-2006B-Q-18 (Conjunta
con AR)
Investigador Principal: Dr. Rodolfo
Barba (ULS)
Título:. "Herbig-Haro
outflows and pre-main sequence stars in M8: deep Gemini
South-GMOS imaging"
Resumen: Although the specific
knowledge of star formation in Orion has been systematically
growing during the last decade, the fact of having
high quality observations in only this region prevents
a full progress in the general comprehension of this
matter. M8 is an excellent example of active star
forming region that can provide important insights
into the birth and development of protostars under
different physical conditions. This would help in
turn to a better testing of our current theoretical
models. Four HH objects have been recently identified
in HST images of the core of M8. Strong additional
evidence of outflows and other signatures of star
formation in the region comes from the analysis of
archival ground-based images. Furthermore, a recent
spectroscopic study lead us to confirm dozens of new
pre-main sequence objects. We therefore propose to
acquire high resolution GMOS images of three selected
fields, which contain these newly detected small-
and parsec-scale HH features and several of the new
T Tauri stars. These images will allow us to find
the structures of the target flows, as well as to
investigate the presence of more star formation features,
such as microjets, proplyds, and silhouette disks.
They will also be used to survey emission objects
identifiable of T Tauri stars down to 0.4 Msun, potential
driving sources of the HH jets.
Tiempo asignado: 2.5 horas
____________________________________________________________________________
Propuesta: GS-2006B-Q-53
Investigador Principal: Dr. Gaspar
Galaz (PUC)
Título: "Stellar velocity
dispersion in bulges and disks of low surface brightness
galaxies"
Resumen: Low surface brightness
galaxies (LSBs) form one of the most enigmatic kind
of galaxies observable in the universe. Their low
stellar density, low stellar formation rate, and the
observational fact that many of them actually present
a significant fraction of old stellar populations,
challenge both stellar formation theories as well
as galaxy formation theories in general. Here, we
propose to investigate the kinematics of the different
stellar populations lying a specially selected sample
of face-on LSBs, already studied in broad-band optical
and near-IR imaging and long-slit optical spectroscopy.
These results, already published, show that small
bulges of LSBs tend to be metal poor, compared to
those larger bulges hosted by LSBs. These conclusions
are in agreement with those by other authors claiming
that secular evolution could explain the bulge formation
of some spiral galaxies. We propose to use GMOS-IFU
in order to measure the velocity dispersion of the
stellar component of the bulges hosted by a selected
sample of 7 LSBs, for which broad properties are known.
We estimate that we can achieve reasonable high S/N
IFU spectra for the disk of one of the selected galaxies.
The IFU spectra will also be useful to estimate the
metallicity gradient of bulges (from the Mgb absorption
line), as well as the mass-to-light ratio from the
measurement of the disk velocity dispersion (sigma_z),
assuming isothermal equilibrium and computing directly
sigma_z thanks to the face-on geometry of the sample.
Using the GMOS-IFU exposure time calculator, we estimate
that we need approximately 1 hr and 20 min on-source
exposure per target, yielding S/N approx. 12. The
total observing time is about 14 hrs.
Tiempo asignado: 14 horas
________________________________________________________________________________________
Propuesta: GS-2006B-Q-77 (Conjunta
con US,CA)
Investigador Principal: Dr. Ezequiel
Treister (UCH)
Título: "GNIRS Spectroscopy
of Extreme X-ray to Optical sources in the E-CDFS
field"
Resumen: We propose to
use GNIRS on Gemini-South to obtain near-infrared
spectroscopy of 4 Extreme X-ray-to-Optical flux ratio
(EXOs) sources found in the Extended Chandra Deep
Field-South field, one of the fields of the Multiwavelength
Survey by Yale-Chile (MUSYC). EXOs are a new class
of X-ray emitters about which almost nothing is known.
In particular, no EXO has measured spectroscopic redshift.
These moderately bright X-ray sources are undetected
in very deep (mag ~27) BVR images obtained as part
of our MUSYC survey. These sources, however, have
~5-sigma detections in our K-band images (~20.5 Vega)
and are clearly detected in the four Spitzer IRAC
bands, implying very red colors of V-K > 7. Given
that they are clearly detected in X-rays and that
they have a very red optical-IR spectrum, these sources
are thought to be either very high redshift AGN (z>6),
or obscured AGN with old or dusty host galaxies at
z~2-3. These sources have brighter fluxes than GOODS
EXOs, hence NIR spectroscopy is possible. NIR spectroscopy
is crucial to distinguish between these two hypotheses.
Only Gemini-S/GNIRS observations can shed light on
the true nature of this new class of highly unusual
sources.
Tiempo asignado: 10 horas
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Propuesta: GS-2006B-Q-66
Investigador Principal: Dr. Nelson
David Padilla (PUC)
Título: "Unveiling
Growth of Spheroids and Black Holes in Dusty Cocoons
upto z=2"
Resumen: We intend to obtain
the spectra of massive star-forming galaxies using
GMOS/Gemini-South to unveil the hidden connection
between the star formation in young massive spheroids
and the growth of their central super massive black
holes. The targeted galaxies were selected as Mid-InfraRed(MIR)
or/and Submm or/and radio bright sources from the
SIRIUS/SXDS field which was observed in multiband
photometry (B,V,R,i',z',J,H, and K_s) with the Subaru/Suprime-Cam
and UH2.2m/SIRIUS. The proposed GMOS observations
explore the following key issues that will shed light
on the co-evolution of star formation and AGN activities
in young massive spheroids; 1) The star formation
rate derived from the strong emitting nebula lines
[OII] lambda3727 for galaxies at z<1.6; 2) The
study of AGN activity in young spheroids using Hbeta
at z<0.6, Mg II at z>0.6 or other emission lines
from narrowor broad-line regions arround the AGNs;
3) The confirmation and determination of redshifts
for massive star forming galaxies such as SMGs, BzKs,
and MIR bright galaxies near the edge of the redshift
desert. Redshift determinations are extremely important
for the study of young massive spheroids since their
redshift distribution is still not well known.
Tiempo asignado: 20 horas
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Propuesta: GS-2006B-Q-75 (Conjunta
con GS)
Investigador Principal: Dr. Marcio
CaTelan (PUC)
Título: "Rotation and
Flattening of Globular Clusters: NGC 121"
Resumen: We wish to conclusively
establish whether rotation can be a main cause of
non-sphericity in globular clusters. Galactic globulars
are constantly interacting with the strong gravitational
potential of the Milky Way, hence it is nearly impossible
to identify the primary reason for their observed
morphologies, even if internal velocity information
exists. What is needed to test the various scenarios
of globular cluster flattening is a non-spherical,
yet isolated extragalactic globular cluster. Our recent
analysis of the lone globular associated with the
low-mass dwarf irregular WLM has recently indicated
that, at least in the case of that old globular cluster,
rotation is not the culprit. Is WLM-1 an anomaly,
or is rotation generally not the primary cause of
globular cluster flattening? Here we propose to provide
insight into this problem by using GMOS-S to study
the lone, old globular cluster associated with the
Small Magellanic Cloud, NGC 121. The resulting velocity
profile will definitely answer the question of whether
rotation can be a cause of the extreme flattening
that is observed in this fairly isolated globular
cluster. Note that this program qualifies as a "poor
weather proposal" as outlined in the 2006B call
for proposals.
Tiempo asignado: 11 horas
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