Propuesta: G/2011A/013
Investigador Principal: Sebastian Lopez, Universidad
de Chile
Título: Surveying the Post-Reionization Universe
with Quasar Spectroscopy III
Resumen: We propose to obtain GMOS-S spectroscopy
of 27 quasars as part of a multi-semester endeavor
tostudy the z>4.4 IGM with Gemini (a related 2011A
GMOS-N proposal is submitted). This request completes
our 3-semester program that will ultimately provide
~160 R~850 spectra of z>4.4 quasars, the largest
homogeneous sample of science-grade high-redshift
quasar spectra in existence.
This sample will yield the first statistically meaningful
measurements of the neutral gas content, the number
density of optically thick absorbers, and the mean
hydrogen absorption at z>4.5. In particular, spectral
stacks will enable the first direct measurement of
the mean free path to ionizing radiation at these
redshifts, and probe its expected strong evolution
near the epoch of reionization. This novel route to
constrain reionization with the Lyman forest requires
a large, homogeneous sample of higherquality spectra
than provided by SDSS. Gemini/GMOS can efficiently
supply these data, which we will publicly release
in reduced form. They will also permit (i) an unparalleled
survey for damped Lya and Lyman limit systems at z>4.5;
(ii) constraints on the mean opacity of Lyman series
transitions; and (iii) a survey for variable emission/absorption
in quasar spectra.
Tiempo asignado: 3.0 hrs.
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Propuesta: G/2011A/016
Investigador Principal: Sebastian Lopez, Universidad
de Chile
Título: Exceptional Swift and Fermi GRBs: Gemini
South Targets of Opportunity
Resumen: Swift and Fermi have led a renaissance in
the study of GRBs, discovering an
unprecedented number of events and promptly alerting
the community to accurate localizations.
However, it is in the follow-up, particularly at optical/infrared
(OIR) wavebands, where the full scientific potential
of these missions is realized. We have recently merged
two GRB ToO teams in order to optimize our GRB science
using the OIR instrument suites on both Gemini telescopes.
Our focus is on extreme and rare GRBs that hold the
greatest potential as unique probes of the universe
and stellar death: 1) high-redshift events (z >
6), offering spectroscopic probes of the universe
during reionization, 2) low-redshift events (z <
1), allowing searches for and detailed studies of
accompanying supernovae, 3) Fermi-LAT bursts, which
require redshift measurements in order to constrain
theories of quantum gravity and place limits on the
Lorentz factor of the outflow and, (4) short GRBs,
with the
goal of constraining their still-mysterious progenitors.
Gemini has emerged as the cornerstone facility of
global GRB research and we will continue to use our
proprietary access on smaller facilities and work
in our wide network of collaborators to maximize the
return of Gemini observations.
Tiempo asignado: 2.0 hrs.
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Propuesta: G/2011A/019
Investigador Principal: Simon Casassus, Universidad
de Chile
Título: Search for planets in disk gaps around
HD142527 and IRS 48.
Resumen: Gaps in protoplanetary disks are tell-tales
of planet formation. Such features have been recently
observed in two protoplanetary disks: 1- around the
HAeBe star HD142527, through JHK AO coronographic
imaging, and diffraction-limited mid-IR imaging, and
2- and around TTauri IRS48, also in the mid-IR. Both
disks are young, although IRS48 appears to be at an
earlier stage of gap clearing.
We propose to search for the putative companions using
NICI spectro- and angular-differential imaging, and
also to map the inner disks and edges of the gaps.
Tiempo asignado: 6.0 hrs.
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Propuesta: G/2011A/007
Investigador Principal: Mario Hamuy, Universidad de
Chile
Título: Rapid ToO time-series spectroscopy
of young supernovae
Resumen: We request an allocation of 12 hours on GMOS
to continue our spectroscopic study of supernovae
(SNe). We request rapid ToO time in order to obtain
a detailed time-series of (8-10) spectra of one or
two young Type-I SN discovered by our CHASE SN search
program, and a very early spectrum of several Type-II
events. Through modeling a time-series of early phase
Type-I supernova spectra, we can study the abundance
stratification of elements in the outer half of the
ejecta. With such an analysis the degree of mixing
and abundances of intermediate-mass-elements will
be determined. This knowledge provides stringent constraints
on the explosion mechanism(s). The early phase spectra
of the Type-II SN will allow us to examine in depth
the physics of the shock breakout. These observations
will provide extremely early and unprecedented coverage
spectroscopy of SNe and will therefore provide valuable
insights into the explosion mechanisms and progneitor
systems of SNe.
Tiempo asignado: 12.0 hrs.
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Propuesta: G/2011A/005
Investigador Principal: J. Jenkins: Universidad de
Chile,
Título: Imaging companions from the Anglo-Australian
Planet Search
Resumen: We have been carryiung out NICI ASDI (Angular
Spectral Differential Imaging) of 31 stars from the
Anglo-Australian Planet Search target list, which
we have found to display the presence of a long-period
companion, at unresolved orbital periods of longer
than the current 12 year span of our precision Doppler
data. These observations will (1) allow us to determine
whether these long-period companions have very long
periods (>20yr) and high masses (ie. brown dwarf
or M-dwarf masses), or shorter periods (12-20yr) and
planetary masses; (2) to do so without the "sin
i" inclination degeneracy that afflicts Doppler
observations; and (3) allow any cool brown dwarfs
so detected to be targetted for follow-up as benchmark
systems of known age and metallicity.
Tiempo asignado: 5.30 hrs.
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Propuesta: G/2011A/017
Investigador Principal: Ricardo Salinas, Universidad
de Concepción
Título: The cD galaxy - cD halo connection
Resumen: The formation mechanism of cD galaxies and
their extended stellar envelopes still holds mysteries.
Many processes, not necessarily exclusive, can be
at play: stellar formation at the bottom of cooling
flows, galactic cannibalism, hierarchical merging,
etc. The existence of cD galaxies exhibiting significant
peculiar velocities respect to their parent cluster
mean velocity is difficult to reconcile with scenarios
requiring the galaxy to be formed at the bottom of
the potential well. Even though galaxies can be formed
outside the cluster and then be accreted, this cannot
happen with cD halos which would not survive the accretion
process due to tidal truncation. These "moving"
cDs raise the following questions: are central galaxies
kinematically coupled to their halos? Can cD-halos
form independently in the central regions of a galaxy
cluster which a galaxy occupies through infall? In
this proposal we aim at the clusters A3653 and A2670,
which present the most extreme cases of "moving"
cDs. Deep, extended spectroscopy of their central
galaxies will allow us to measure mean velocity and
velocity dispersion profiles as well as ages and metallicities
of the galaxies and their cD halos, helping us to
answer the question whether these galaxies and halos
share a common origin.
Tiempo asignado: 12.17
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Propuesta: G/2011A/004
Investigador Principal: Timo Anguita Pontificia Universidad
Catolica de Chile
Título: Mass to light ratios and evolution
of galaxy scale lenses from the RCS2
Resumen: We have built a catalog of ~60 strong
galaxy-galaxy lensing systems at intermediate redshift
from fields of the RCS2. Here, we propose to obtain
spectroscopic observations of 10 southern candidates
observable during period 2011A. The lens galaxies
in our catalog are particularly interesting because
the sample they constitute is complementary in redshift
to the SLACS and COSMOS sample, with brightnesses
similar to that of the SLACS lenses. With spectroscopic
information of these candidates we will be able to
confirm their lens nature and perform mass models.
These mass models will allow us to measure the total
mass and dark matter fraction of galaxies at their
redshift range putting a clear constraint on galaxy
evolution models. As our lens models will benefit
from the environmental information already at hand,
we will additionally be able to measure the influence
of this environment and its redshift evolution
Tiempo asignado: 20.0 hrs.
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Propuesta: G/2011A/011
Investigador Principal: Matthias Schreiber: Universidad
de Valparaíso
Título: The faintest members of the cataclysmic
variable population
Resumen: Cataclysmic variables are common
and structurally simple binaries in which a white
dwarf accretes from a low-mass companion. As such,
they are an excellent benchmark population to test,
calibrate, and further develop binary population synthesis
models. These models are used in a wide range of contexts
including the formation of binary pulsars and for
analysing the observed mixture of short/long delay
Type Ia supernovae. The Sloan Digital Sky Survey (SDSS)
produced the deepest and most homogenous CV sample
to date, highlighting the importance of the faintest
systems to confirm and calibrate models. It uncovered
for first time the previously 'missing' short period
CVs predicted by models and showed that they are intrinsically
faint systems. The spectroscopic completeness of SDSS
plummets below i=19.1 however, and it is exactly in
this range that the composition of the Galactic CV
population undergoes a major change. Towards fainter
magnitudes the fraction of low-luminosity systems
increase and probably dominate the space density of
CVs. We propose here to extend the depth of the SDSS
CV sample by obtaining GMOS observations of faint
CV candidates in the SDSS footprint, along with GTC
and VLT observations.
Tiempo asignado: 15.0 hrs.
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Propuesta: G/2011A/014
Investigador Principal: Luis Vega Neme Universidad
de Valparaíso
Título: Unveiling the nature of Blue Compact
Dwarf galaxies with IFU
Resumen: This proposal aims at getting Integral Field
Unit (IFU) spectra of a Blue Compact Dwarf (BCD) galaxy
in order to characterize its stellar populations,
internal kinematic and chemical composition. This
technique has demonstrated to be a powerful tool for
such kind of studies (e.g. Lagos et al. 2009, ApJ,
137, 5068) and will help to adress important questions
related with the nature of these objects. Here we
focus on the galaxy UM452. Despite there are previous
photometric and spectroscopic studies of this system,
an spectroscopic analysis with spatial resolution
is still lacking.
This study will be interesting in its own and for
a potential comparison with other BCDs observed with
similar instruments. There is a related proposal sent
to Gemini North to obtain IFU data of an additional
unexplored system. It is planned to increase our sample
of BCDs observed with IFU in the following semesters.
Our long term project aims at identifying common features
of isolated systems, thereby contributing to a more
exhaustive understanding of these exciting objects.
Data for this project was obtained in semester 2010B
(Proposal ID: GN-2010B-Q-69, PI: L. Vega Neme).
Tiempo asignado: 15.32 hrs.
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Propuesta:
G/2011A/008
Investigador Principal: Alberto Rebassa-Mansergas
Universidad de Valparaíso
Título: Finding double degenerates in the Sloan
Digital Sky Survey
Resumen: Double white dwarf binaries, or double-degenerates
(DD) are key systems in two major astrophysical topics:
they are potential progenitors of supernovae type
Ia, and definite sources of gravitational wave radiation
that will be detected by forthcoming missions such
as LISA. However, currently we only know a handful
of DDs, and their evolution is poorly understood,
and consequently rates of SNIa from DDs are very uncertain,
as is the galactic foreground gravitational wave signal.
The Sloan Digital Sky Survey has increased the number
of know white dwarfs by a factor of ~10, and we propose
to use GMOS on Gemini-N/S to carry out a dedicated
search for DDs among this large sample of new white
dwarfs. We will focus on systems where a low-mass
(<0.5Msun) white dwarf dominates the optical spectrum,
as this is a strong signature of comon envelope (binary)
evolution.
Unseen companions are likely to be more massive white
dwarfs with smaller radii/surface area. Two radial
velocity snapshot obtained randomly throughout 11A
will unambiguously identifiy the DDs among our targets,
and will be subject to period determinations in future
semesters.
Tiempo asignado: 10.0 hrs.
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Propuesta:
G/2011A/009
Investigador Principal: Andre-Nicolas Chene Universidad
de Concepción
Título: Constraining the evolution of young
star clusters
Resumen: Observations show that young star clusters
lose a significant fraction of their initial content
of massive stars owing to dynamical processes in their
dense cores. The ejected (runaway) stars generate
bow shocks, whose geometry allows us to back-trace
the orbits of the stars to parent clusters. Search
for bow shocks in star-forming regions and subsequent
identification of their associated stars serve as
a useful tool for constraining the dynamical evolution
of their parent clusters, and particularly for distinguishing
between the primordial and the dynamical origins of
mass segregation in star clusters. In the current
project, we propose spectroscopic follow-up of nine
bow shock-producing stars, detected around the young
clusters NGC 3603 and Trumpler 16 using the Spitzer
Space Telescope archival data. With the spectroscopic
data, we will be able to determine the spectral types,
luminosities and masses of the stars, to measure their
radial velocities and thereby to determine their cluster
membership. Together with the proper motion measurements
for our program stars, the results of the spectroscopic
follow-up will provide novel constraints on the modeling
of young star clusters, which in turn would have profound
consequences for understanding the origin of the field
OB stars.
Tiempo
asignado: 8.7 hrs.
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