HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5042
PERIOD
COVERED: 5am February 26 - 5am March 1, 2010 (DOY 057/10:00z-060/10:00z)
OBSERVATIONS
SCHEDULED
WFC3/UV
12049
Improve
the Measurement of Vesta's Pole Orientation to Support Dawn
Mission
NASA’s
Dawn spacecraft is scheduled to go into orbit around the main
belt
asteroid 4 Vesta in July 2011. Currently the project is using a 3-‘
pole
position uncertainty of Vesta of 12’ for spacecraft trajectory
design.
We have determined that with an additional set of Hubble
observations
at Vesta’s next opposition in February 2010, that the pole
position
uncertainty can be reduced by a factor of 4. This will reduce
both
cost and risk to the Dawn mission, and is likely to increase the
stay
time at Vesta and will add to the scientific return of the mission.
The
requested observing window in February 2010 is the last and single
best
opportunity that can benefit the Dawn mission, but it is before the
start
of the next HST Cycle.
WFC3/UVIS
12018
Ultra-Luminous
X-Ray Sources in the Most Metal-Poor Galaxies
There
is growing observational and theoretical evidence to suggest that
Ultra-Luminous
X-ray sources (ULX) form preferentially in low
metallicity
environments. Here we propose a survey of 27 nearby (<
30Mpc)
star-forming Extremely Metal Poor Galaxies (Z<5% solar). There
are
almost no X-ray observations of such low abundance galaxies (3 in
the
Chandra archive). These are the most metal-deficient galaxies known,
and
a logical place to find ULX if they favor metal-poor systems. We
plan
to test recent population synthesis models which predict that ULX
should
be very numerous in metal-poor galaxies. We will also test the
hypothesis
that ULX form in massive young star clusters, and ask for HST
time
to obtain the necessary imaging data.
COS/FUV
12011
Magnetic
Heating of the Outer Atmospheres of Very Low Mass Dwarfs
The
detections of FUV and X-ray emissions from very low mass stars and
brown
dwarfs have confirmed that stellar magnetic activity can survive
even
at these low stellar masses. The emissions are qualitatively
similar
to those from active stars, despite the dramatic differences
between
the characteristics of an ultracool (>M7) stellar atmosphere and
those
of earlier type cool stars. It is currently an open question how
the
structures and magnetic heating which exists in these very low mass
stars
compare with those seen in higher mass active stars. We propose to
take
Chandra and HST/COS spectra of two nearby active very low mass
stars
in order to determine the effect that these large-scale fields
have
on transition region and coronal structures.
ACS/WFC
11995
CCD
Daily Monitor (Part 2)
This
program comprises basic tests for measuring the read noise and dark
current
of the ACS WFC and for tracking the growth of hot pixels. The
recorded
frames are used to create bias and dark reference images for
science
data reduction and calibration. This program will be executed
four
days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To
facilitate
scheduling, this program is split into three proposals. This
proposal
covers 320 orbits (20 weeks) from 1 February 2010 to 20 June
2010.
WFC3/IR/S/C
11929
IR
Dark Current Monitor
Analyses
of ground test data showed that dark current signals are more
reliably
removed from science data using darks taken with the same
exposure
sequences as the science data, than with a single dark current
image
scaled by desired exposure time. Therefore, dark current images
must
be collected using all sample sequences that will be used in
science
observations. These observations will be used to monitor changes
in
the dark current of the WFC3-IR channel on a day-to-day basis, and to
build
calibration dark current ramps for each of the sample sequences to
be
used by Gos in Cycle 17. For each sample sequence/array size
combination,
a median ramp will be created and delivered to the
calibration
database system (CDBS).
WFC3/UVIS
11908
Cycle
17: UVIS Bowtie Monitor
Ground
testing revealed an intermittent hysteresis type effect in the
UVIS
detector (both CCDs) at the level of ~1%, lasting hours to days.
Initially
found via an unexpected bowtie-shaped feature in flatfield
ratios,
subsequent lab tests on similar e2v devices have since shown
that
it is also present as simply an overall offset across the entire
CCD,
i.e., a QE offset without any discernable pattern. These lab tests
have
further revealed that overexposing the detector to count levels
several
times full well fills the traps and effectively neutralizes the
bowtie.
Each visit in this proposal acquires a set of three 3x3 binned
internal
flatfields: the first unsaturated image will be used to detect
any
bowtie, the second, highly exposed image will neutralize the bowtie
if
it is present, and the final image will allow for verification that
the
bowtie is gone.
WFC3/UVIS
11907
UVIS
Cycle 17 Contamination Monitor
The
UV throughput of WFC3 during Cycle 17 is monitored via weekly
standard
star observations in a subset of key filters covering 200-600nm
and
F606W, F814W as controls on the red end. The data will provide a
measure
of throughput levels as a function of time and wavelength,
allowing
for detection of the presence of possible contaminants.
WFC3/UVIS
11905
WFC3
UVIS CCD Daily Monitor
The
behavior of the WFC3 UVIS CCD will be monitored daily with a set of
full-frame,
four-amp bias and dark frames. A smaller set of 2Kx4K
subarray
biases are acquired at less frequent intervals throughout the
cycle
to support subarray science observations. The internals from this
proposal,
along with those from the anneal procedure (Proposal 11909),
will
be used to generate the necessary superbias and superdark reference
files
for the calibration pipeline (CDBS).
FGS
11875
Monitoring
FGS2R2 Distortion and Alignment After SMOV4
This
proposal monitors changes in the FGS2R2 distortion and alignment
after
SMOV4 by observing selected stars in M35 in Position mode. Data
from
each epoch are compared to track changes in FGS2R2. When the rate
of
change becomes sufficiently slow, FGS2R2 will be cleared for a
mini-OFAD
and FGS-FGS alignment calibration (carried out in another
phase
2 proposal).
FGS
11871
Long
Term Stability of FGS1R in Position Mode
This
proposal resumes the Long Term Monitoring of FGS1R in Position Mode
using
stars in M35 that are a subset of the FGS "OFAD catalog" using
both
the "fall" and "spring" seasons (the spring orient was not
available
under two gyro mode). The data acquired by this proposal are
used
to update the FGS1R "rhoA & kA" parameters that are associated
with
the
OFAD solution that is applicable at the observation's epoch. These
values
are critical to support sub-milli arcsecond astrometry with
FGS1R.
This
particular proposal also include a FGS3 visit to M35 for post SM4
verification
of its calibration status.
STIS/CCD
11846
CCD
Bias Monitor-Part 1
The
purpose of this proposal is to monitor the bias in the 1x1, 1x2,
2x1,
and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up
high-S/N
superbiases and track the evolution of hot columns.
STIS/CCD
11844
CCD
Dark Monitor Part 1
The
purpose of this proposal is to monitor the darks for the STIS CCD.
WFC3/UVIS/IR
11835
The
Multi-Faceted X-Ray Activity of Low-Redshift Active Galaxies
We
propose ACIS-I observations of Chandra-unobserved low-redshift 3CRR
active
galaxies and their environments. The data will complete Chandra
observations
of 3CRR at z < 0.1, making the sample useful for
statistical
studies. Only Chandra can resolve the multiple components of
these
sources, as is needed for an improved understanding of source
physics
and gas heating. The imaging and spectroscopy of cores, jets,
hot
spots, and atmospheres will be of permanent legacy value. We will
use
the data to investigate particle acceleration, interactions between
radio
plasma and the ISM and IGM, the emission mechanisms of hot spots,
and
AGN fueling. Comparison with our complete Spitzer coverage and HST
images
will aid interpretation. The dataset will be made public
immediately.
ACS/WFC3
11735
The
LSD Project: Dynamics, Merging and Stellar Populations of a Sample
of
Well-Studied LBGs at z~3
A
large observational effort with the ground-based ESO/VLT telescopes
allowed
us to obtain deep, spatially-resolved, near-IR spectra of
complete
sample of 11 Lyman-Break Galaxies at z~3.1. These observations
were
used to obtain, for the first time, the metallicity and the
dynamical
properties of a sample of objects that, albeit small, is
representative
of the total population of the LBGs. We propose to use
HST
to obtain high-resolution optical and near-IR images of this sample
of
LBGs in order to study the broad-band morphology and the stellar
light
distribution of these galaxies. These images, exploiting the
superior
spatial resolution of HST images and the low-background : 1-
will
allow a precise measure of the dynamical mass from the velocity
field
derived with spectroscopy; 2- will permit a comparison of the
distribution
of star formation (from the line emission) with the
underlying
stellar population, and, 3- will be used to check if the
complex
velocity field and the multiple line-emitting regions detected
in
most targets can be ascribed to on-going mergers. This accurate study
will
shed light on a number of unsolved problems still affecting the
knowledge
of the LBGs.
WFC3/UVIS
11732
The
Temperature Profiles of Quasar Accretion Disks
We
can now routinely measure the size of quasar accretion disks using
gravitational
microlensing of lensed quasars. At optical wavelengths we
observe
a size and scaling with black hole mass roughly consistent with
thin
disk theory but the sizes are larger than expected from the
observed
optical fluxes. One solution would be to use a flatter
temperature
profile, which we can study by measuring the wavelength
dependence
of the disk size over the largest possible wavelength
baseline.
Thus, to understand the size discrepancy and to probe closer
to
the inner edge of the disk we need to extend our measurements to UV
wavelengths,
and this can only be done with HST. For example, in the UV
we
should see significant changes in the optical/UV size ratio with
black
hole mass. We propose monitoring 5 lenses spanning a broad range
of
black hole masses with well-sampled ground based light curves,
optical
disk size measurements and known GALEX UV fluxes during Cycles
17
and 18 to expand from our current sample of two lenses. We would
obtain
5 observations of each target in each Cycle, similar to our
successful
strategy for the first two targets.
COS/NUV/FUV
11727
UV
Spectroscopy of Local Lyman Break Galaxy Analogs: New Clues to Galaxy
Formation
in the Early Universe
Much
of our information about galaxy evolution and the interaction
between
galaxies and the IGM at high-z has been provided by the Lyman
Break
Galaxies (LBGs). However, it is difficult to investigate these
faint
and distant objects in detail. To address this, we have used the
GALEX
All-Sky Imaging Survey and the SDSS to identify for the first time
a
rare population of low- redshift galaxies with properties remarkably
similar
to the high-redshift LBGs. These local "Lyman Break Analogs"
(LBAs)
resemble LBGs in terms of morphology, size, UV luminosity, star
formation
rate, UV surface brightness, stellar mass, velocity
dispersion,
metallicity, and dust content. We are assembling a wide
range
of data on these objects with the goal of using them as local
laboratories
for better understanding the relevant astrophysical
processes
in LBGs. These data include HST imaging (95 orbits in Cy15 and
16),
Spitzer photometry and spectroscopy, Chandra and XMM X-ray imaging
and
spectroscopy, and near-IR integral field spectroscopy (VLT, Keck,
and
Gemini). In this proposal we are requesting the most important
missing
puzzle piece: far-UV spectra with a signal-to-noise and spectral
resolution
significantly better than available for typical LBGs. We will
use
these spectra to study the LBA's galactic winds, probe the processes
that
regulate the escape of Ly-a and Lyman continuum radiation,
determine
chemical abundances for the stars and gas, and constrain the
form
of the high-end of the Initial Mass Function. Adding these new COS
data
will give us vital information about these extraordinary sites of
star
formation in the local universe. In so-doing it will also shed new
light
on the processes that led to the formation of stars, the building
of
galaxies, and the enrichment and heating of the IGM in the early
universe.
WFC3/IR
11719
A
Calibration Database for Stellar Models of Asymptotic Giant Branch
Stars
Studies
of galaxy formation and evolution rely increasingly on the
interpretation
and modeling of near-infrared observations. At these
wavelengths,
the brightest stars are intermediate mass asymptotic giant
branch
(AGB) stars. These stars can contribute nearly 50% of the
integrated
luminosity at near infrared and even optical wavelengths,
particularly
for the younger stellar populations characteristic of
high-redshift
galaxies (z>1). AGB stars are also significant sources of
dust
and heavy elements. Accurate modeling of AGB stars is therefore of
the
utmost importance.
The
primary limitation facing current models is the lack of useful
calibration
data. Current models are tuned to match the properties of
the
AGB population in the Magellanic Clouds, and thus have only been
calibrated
in a very narrow range of sub-solar metallicities.
Preliminary
observations already suggest that the models are
overestimating
AGB lifetimes by factors of 2-3 at lower metallicities.
At
higher (solar) metallicities, there are no appropriate observations
for
calibrating the models.
We
propose a WFC3/IR SNAP survey of nearby galaxies to create a large
database
of AGB populations spanning the full range of metallicities and
star
formation histories. Because of their intrinsically red colors and
dusty
circumstellar envelopes, tracking the numbers and bolometric
fluxes
of AGB stars requires the NIR observations we propose here. The
resulting
observations of nearby galaxies with deep ACS imaging offer
the
opportunity to obtain large (100-1000's) complete samples of AGB
stars
at a single distance, in systems with well-constrained star
formation
histories and metallicities.
WFC3/UVIS
11714
Snapshot
Survey for Planetary Nebulae in Local Group Globular Clusters
Planetary
nebulae (PNe) in globular clusters (GCs) raise a number of
interesting
issues related to stellar and galactic evolution. The number
of
PNe known in Milky Way GCs, four, is surprisingly low if one assumes
that
all stars pass through a PN stage. However, it is likely that the
remnants
of stars now evolving in galactic GCs leave the AGB so slowly
that
any ejected nebula dissipates long before the star becomes hot
enough
to ionize it. Thus there should not be ANY PNe in Milky Way
GCs--but
there are four! It has been suggested that these Pne are the
result
of mergers of binary stars within GCs, i.e., that they are
descendants
of blue stragglers. The frequency of occurrence of PNe in
external
galaxies poses more questions, because it shows a range of
almost
an order of magnitude.
I
propose a SNAPshot survey aimed at discovering PNe in the GC systems
of
Local Group galaxies outside the Milky Way. These clusters, some of
which
may be much younger than their counterparts in our galaxy, might
contain
many more PNe than those of our own galaxy. I will use the
standard
technique of emission-line and continuum imaging, which easily
discloses
PNe. This proposal continues a WFPC2 program started in Cycle
16,
but with the more powerful WFC3. As a by-product, the survey will
also
produce color-magnitude diagrams for numerous clusters for the
first
time, reaching down to the horizontal branch.
ACS/WFC/WFC3/UV
11711
A
Definitive Distance to the Coma Core Ellipticals
As
the richest galaxy cluster in the local universe (cz < 10, 000 km/s),
the
Coma cluster continues to serve as the standard of comparison for
numerous
studies of galaxy properties and scaling relations in clusters.
The
central importance of Coma has been recognized with two recent HST
large
programs: a Treasury survey to study the dwarf galaxy population
by
imaging 82 different ACS/WFC pointings, and a program to measure
Cepheid
distances to two spiral galaxies projected within the Coma core
region.
An accurate distance to the Coma core is essential for comparing
the
galaxy luminosities and sizes to nearby galaxies in Virgo and
Fornax,
while an accurate peculiar velocity is needed for correctly
tying
to more distant clusters. However, experience dictates that
Cepheid
distances to clusters must be carefully verified against
accurate
measurements to the dominant early-type population, especially
for
such an unprecedented effort as the Coma Cepheid search (the
completion
of which remains uncertain). We propose to measure highly
accurate
(3-4% internal error per galaxy) SBF distances to the two giant
Coma
core ellipticals. The reliability of the SBF method with the
ACS/WFC
has been repeatedly demonstrated, and it is so efficient that it
requires
only 3% of the number of orbits dedicated to the two current
large
Coma programs. The precise ACS SBF Coma core distance will also
provide
a good constraint on the Coma peculiar velocity, thus improving
the
accuracy of comparisons to distant clusters. Finally, our program
will
answer some longstanding puzzles surrounding the rich globular
cluster
population in the core of this archetypal galaxy cluster.
WFC3/UVIS/IR
11702
Search
for Very High-z Galaxies with WFC3 Pure Parallel
WFC3
will provide an unprecedented probe to the early universe beyond
the
current redshift frontier. Here we propose a pure parallel program
using
this new instrument to search for Lyman-break galaxies at
6.5<z<8.8
and to probe the epoch of reionization, a hallmark event in
the
history of the early universe. We request 200 orbits, spreading over
30
~ 50 high Galactic latitude visits (|b|>20deg) that last for 4 orbits
and
longer, resulting a total survey area of about 140~230 square
arcminute.
Based on our understanding of the new HST parallel
observation
scheduling process, we believe that the total number of
long-duration
pure parallel visits in Cycle 17 should be sufficient to
accommodate
our program. We waive all proprietary rights to our data,
and
will also make the enhanced data products public in a timely manner.
(1)
We will use both the UVIS and the IR channels, and do not need to
seek
optical data from elsewhere.
(2)
Our program will likely triple the size of the probable candidate
samples
at z~7 and z~8, and will complement other targeted programs
aiming
at the similar redshift range.
(3)
Being a pure parallel program, our survey will only make very
limited
demand on the scarce HST resources. More importantly, as the
pure
parallel pointings will be at random sight-lines, our program will
be
least affected by the bias due to the large scale structure ("cosmic
variance").
(4)
We aim at the most luminous LBG population, and will address the
bright-end
of the luminosity function at z~8 and z~7. We will constrain
the
value of L* in particular, which is critical for understanding the
star
formation process and the stellar mass assembly history in the
first
few hundred million years of the universe.
(5)
The candidates from our survey, most of which will be the brightest
ones
that any surveys would be able to find, will have the best chance
to
be spectroscopically confirmed at the current 8--10m telescopes.
(6)
We will also find a large number of extremely red, old galaxies at
intermediate
redshifts, and the fine spatial resolution offered by the
WFC3
will enable us constrain their formation history based on the study
of
their morphology, and hence shed light on their connection to the
very
early galaxies in the universe.
COS/FUV
11687
SNAPing
Coronal Iron
This
is a Snapshot Survey to explore two forbidden lines of highly
ionized
iron in late-type coronal sources. Fe XII 1349 (T~ 2 MK) and Fe
XXI
1354 (T~ 10 MK) -- well known to Solar Physics -- have been detected
in
about a dozen cool stars, mainly with HST/STIS. The UV coronal
forbidden
lines are important because they can be observed with velocity
resolution
of better than 15 km/s, whereas even the state-of-the-art
X-ray
spectrometers on Chandra can manage only 300 km/s in the kilovolt
band
where lines of highly ionized iron more commonly are found. The
kinematic
properties of hot coronal plasmas, which are of great interest
to
theorists and modelers, thus only are accessible in the UV at
present.
The bad news is that the UV coronal forbidden lines are faint,
and
were captured only in very deep observations with STIS. The good
news
is that 3rd-generation Cosmic Origins Spectrograph, slated for
installation
in HST by SM4, in a mere 25 minute exposure with its G130M
mode
can duplicate the sensitivity of a landmark 25-orbit STIS E140M
observation
of AD Leo, easily the deepest such exposure of a late-type
star
so far. Our goal is to build up understanding of the properties of
Fe
XII and Fe XXI in additional objects beyond the current limited
sample:
how the lineshapes depend on activity, whether large scale
velocity
shifts can be detected, and whether the dynamical content of
the
lines can be inverted to map the spatial morphology of the stellar
corona
(as in "Doppler Imaging''). In other words, we want to bring to
bear
in the coronal venue all the powerful tricks of spectroscopic
remote
sensing, well in advance of the time that this will be possible
exploiting
the corona's native X-ray radiation. The 1290-1430 band
captured
by side A of G130M also contains a wide range of key plasma
diagnostics
that form at temperatures from below 10, 000 K (neutral
lines
of CNO), to above 200, 000 K (semi-permitted O V 1371), including
the
important bright multiplets of C II at 1335 and Si IV at 1400;
yielding
a diagnostic gold mine for the subcoronal atmosphere. Because
of
the broad value of the SNAP spectra, beyond the coronal iron project,
we
waive the normal proprietary rights.
WFC3/UVIS
11650
Mutual
Orbits, Colors, Masses, and Bulk Densities of 3 Cold Classical
Trans-Neptunian
Binaries
Many
Trans-Neptunian Objects (TNOs) have been found to be binary or
multiple
systems. As in other astrophysical settings, Trans-Neptunian
Binaries
(TNBs) offer uniquely valuable information. Their mutual orbits
allow
the direct determination of their system masses, perhaps the most
fundamental
physical quantity of any astronomical object. Their
frequency
of occurrence and dynamical characteristics provide clues to
formation
conditions and evolution scenarios affecting both the binaries
and
their single neighbors. Combining masses with sizes, bulk densities
can
be measured. Densities constrain bulk composition and internal
structure,
key clues to TNO origins and evolution over time. Several TNB
bulk
densities have been determined, hinting at interesting trends. But
none
of them belongs to the Cold Classical sub-population, the one group
of
TNOs with demonstrably distinct physical characteristics. Two
top-priority
Spitzer programs will soon observe and measure the sizes of
3
Cold Classical TNBs. This proposal seeks to determine the mutual
orbits
and thus masses of these systems, enabling computation of their
densities.
WFC3/UVIS/IR
11644
A
Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into
the
Formation of the Outer Solar System
The
eight planets overwhelmingly dominate the solar system by mass, but
their
small numbers, coupled with their stochastic pasts, make it
impossible
to construct a unique formation history from the dynamical or
compositional
characteristics of them alone. In contrast, the huge
numbers
of small bodies scattered throughout and even beyond the
planets,
while insignificant by mass, provide an almost unlimited number
of
probes of the statistical conditions, history, and interactions in
the
solar system. To date, attempts to understand the formation and
evolution
of the Kuiper Belt have largely been dynamical simulations
where
a hypothesized starting condition is evolved under the
gravitational
influence of the early giant planets and an attempt is
made
to reproduce the current observed populations. With little
compositional
information known for the real Kuiper Belt, the test
particles
in the simulation are free to have any formation location and
history
as long as they end at the correct point. Allowing compositional
information
to guide and constrain the formation, thermal, and
collisional
histories of these objects would add an entire new dimension
to
our understanding of the evolution of the outer solar system. While
ground
based compositional studies have hit their flux limits already
with
only a few objects sampled, we propose to exploit the new
capabilities
of WFC3 to perform the first ever large-scale
dynamical-compositional
study of Kuiper Belt Objects (KBOs) and their
progeny
to study the chemical, dynamical, and collisional history of the
region
of the giant planets. The sensitivity of the WFC3 observations
will
allow us to go up to two magnitudes deeper than our ground based
studies,
allowing us the capability of optimally selecting a target list
for
a large survey rather than simply taking the few objects that can be
measured,
as we have had to do to date. We have carefully constructed a
sample
of 120 objects which provides both overall breadth, for a general
understanding
of these objects, plus a large enough number of objects in
the
individual dynamical subclass to allow detailed comparison between
and
within these groups. These objects will likely define the core
Kuiper
Belt compositional sample for years to come. While we have many
specific
results anticipated to come from this survey, as with any
project
where the field is rich, our current knowledge level is low, and
a
new instrument suddenly appears which can exploit vastly larger
segments
of the population, the potential for discovery -- both
anticipated
and not -- is extraordinary.
WFC3/ACS/IR
11597
Spectroscopy
of IR-Selected Galaxy Clusters at 1 < z < 1.5
We
propose to obtain WFC3 G141 and G102 slitless spectroscopy of galaxy
clusters
at 1 < z < 1.5 that were selected from the IRAC survey of the
Bootes
NDWFS field. Our IRAC survey contains the largest sample of
spectroscopically
confirmed clusters at z > 1. The WFC3 grism data will
measure
H-alpha to determine SFR, and fit models to the low resolution
continua
to determine stellar population histories for the brighter
cluster
members, and redshifts for the red galaxies too faint for
ground-based
optical spectroscopy.
WFC3/UVIS
11595
Turning
Out the Light: A WFC3 Program to Image z>2 Damped Lyman Alpha
Systems
We
propose to directly image the star-forming regions of z>2 damped Lya
systems
(DLAs) using the WFC3/UVIS camera on the Hubble Space Telescope.
In
contrast to all previous attempts to detect the galaxies giving rise
to
high redshift DLAs, we will use a novel technique that completely
removes
the glare of the background quasar. Specifically, we will target
quasar
sightlines with multiple DLAs and use the higher redshift DLA as
a
``blocking filter'' (via Lyman limit absorption) to eliminate all FUV
emission
from the quasar. This will allow us to carry out a deep search
for
FUV emission from the lower redshift DLA, shortward of the Lyman
limit
of the higher redshift absorber. The unique filter set and high
spatial
resolution afforded by WFC3/UVIS will then enable us to directly
image
the lower redshift DLA and thus estimate its size, star- formation
rate
and impact parameter from the QSO sightline. We propose to observe
a
sample of 20 sightlines, selected primarily from the SDSS database,
requiring
a total of 40 HST orbits. The observations will allow us to
determine
the first FUV luminosity function of high redshift DLA
galaxies
and to correlate the DLA galaxy properties with the ISM
characteristics
inferred from standard absorption-line analysis to
significantly
improve our understanding of the general DLA population.
WFC3/UVIS
11594
A
WFC3 Grism Survey for Lyman Limit Absorption at z=2
We
propose to conduct a spectroscopic survey of Lyman limit absorbers at
redshifts
1.8 < z < 2.5, using WFC3 and the G280 grism. This proposal
intends
to complete an approved Cycle 15 SNAP program (10878), which was
cut
short due to the ACS failure. We have selected 64 quasars at 2.3 < z
<
2.6 from the Sloan Digital Sky Survey Spectroscopic Quasar Sample, for
which
no BAL signature is found at the QSO redshift and no strong metal
absorption
lines are present at z > 2.3 along the lines of sight. The
survey
has three main observational goals. First, we will determine the
redshift
frequency dn/dz of the LLS over the column density range 16.0 <
log(NHI)
< 20.3 cm^-2. Second, we will measure the column density
frequency
distribution f(N) for the partial Lyman limit systems (PLLS)
over
the column density range 16.0 < log(NHI) < 17.5 cm^-2. Third, we
will
identify those sightlines which could provide a measurement of the
primordial
D/H ratio. By carrying out this survey, we can also help
place
meaningful constraints on two key quantities of cosmological
relevance.
First, we will estimate the amount of metals in the LLS using
the
f(N), and ground based observations of metal line transitions.
Second,
by determining f(N) of the PLLS, we can constrain the amplitude
of
the ionizing UV background at z~2 to a greater precision. This survey
is
ideal for a snapshot observing program, because the on-object
integration
times are all well below 30 minutes, and follow-up
observations
from the ground require minimal telescope time due to the
QSO
sample being bright.
WFC3/ACS/IR
11584
Resolving
the Smallest Galaxies with ACS
An
order of magnitude more dwarf galaxies are expected to inhabit the
Local
Group, based on currently accepted galaxy formation models, than
have
been observed. This discrepancy has been noted in environments
ranging
from the field to rich clusters, with evidence emerging that
lower
density regions contain fewer dwarfs per giant than higher density
regions,
in further contrast to model predictions. However, there is no
complete
census of the faintest dwarf galaxies in any environment. The
discovery
of the smallest and faintest dwarfs is hampered by the
limitations
in detecting such compact or low surface brightness
galaxies,
and this is compounded by the great difficulty in determining
accurate
distances to, or ascertaining group membership for, such faint
objects.
The M81 group provides a powerful means for establishing
membership
for faint galaxies in a low density region. With a distance
modulus
of 27.8, the tip of the red giant branch (TRGB) appears at I ~
24,
just within the reach of ground based surveys. We have completed a
65
square degree survey in the region around M81 with the CFHT/MegaCam.
Half
of our survey was completed before Cycle 16 and we were awarded
time
with WFPC2 to observe 15 new candidate dwarf galaxy group members
in
F606W and F814W bands in order to construct color-magnitude diagrams
from
which to measure accurate TRGB distances and determine star
formation
and metallicity histories. The data obtained show that 8 - 9
of
these objects are galaxies at the same distance as M81. In completing
our
survey, we have discovered an additional 8 candidate galaxies we
propose
to image with ACS in order to measure TRGB distances and
establish
membership. We also wish to re-observe our smallest candidate
group
member and a tidal dwarf candidate with deeper observations made
possible
with ACS. Once membership has been established for this second
set
of candidates, we will have a complete census of the dwarf galaxy
population
in the M8 group to M_r ~ -10, allowing us to obtain a firm
measurement
of the luminosity function faint-end slope, and, combined
with
previous HST data, to provide a complete inventory of the age and
abundance
properties for the collapsed core of the M81 group.
WFC3/UVIS
11565
A
Search for Astrometric Companions to Very Low-Mass, Population II
Stars
We
propose to carry out a Snapshot search for astrometric companions in
a
subsample of very low-mass, halo subdwarfs identified within 120
parsecs
of the Sun. These ultra-cool M subdwarfs are local
representatives
of the lowest-mass H burning objects from the Galactic
Population
II. The expected 3-4 astrometric doubles that will be
discovered
will be invaluable in that they will be the first systems
from
which gravitational masses of metal-poor stars at the bottom of the
main
sequence can be directly measured.
NIC2/WFC3/IR
11219
Active
Galactic Nuclei in Nearby Galaxies: A New View of the Origin of
the
Radio-Loud Radio- Quiet Dichotomy?
Using
archival HST and Chandra observations of 34 nearby early-type
galaxies
(drawn from a complete radio selected sample) we have found
evidence
that the radio-loud/radio-quiet dichotomy is directly connected
to
the structure of the inner regions of their host galaxies in the
following
sense: [1] Radio-loud AGN are associated with galaxies with
shallow
cores in their light profiles [2] Radio-quiet AGN are only
hosted
by galaxies with steep cusps. Since the brightness profile is
determined
by the galaxy's evolution, through its merger history, our
results
suggest that the same process sets the AGN flavor. This provides
us
with a novel tool to explore the co-evolution of galaxies and
supermassive
black holes, and it opens a new path to understand the
origin
of the radio-loud/radio-quiet AGN dichotomy. Currently our
analysis
is statistically incomplete as the brightness profile is not
available
for 82 of the 116 targets. Most galaxies were not observed
with
HST, while in some cases the study is obstructed by the presence of
dust
features. We here propose to perform an infrared NICMOS snapshot
survey
of these 82 galaxies. This will enable us to i) test the reality
of
the dichotomic behavior in a substantially larger sample; ii) extend
the
comparison between radio-loud and radio-quiet AGN to a larger range
of
luminosities.
WFC3/IR
11208
The
Co-Evolution of Spheroids and Black Holes in the Last Six Billion
Years
The
masses of giant black holes are correlated with the luminosities,
masses,
and velocity dispersions of the bulges of their host galaxies.
This
empirical correlation of phenomena on widely different scales (from
pcs
to kpcs) suggests that the formation and evolution of galaxies and
central
black holes are closely linked. In Cycle 13, we have started a
campaign
to map directly the co-evolution of spheroids and black-holes
by
measuring in observationally favorable redshift windows the empirical
correlations
connecting their properties. By focusing on Seyfert 1s,
where
the nucleus and the stars contribute comparable fractions of total
light,
black hole mass and bulge dispersion are obtained from Keck
spectroscopy.
HST is required for accurate measurement of the
non-stellar
AGN continuum, the morphology of the galaxy, and the
structural
parameters of the bulge. The results at z=0.36 indicate a
surprisingly
fast evolution of bulges in the past 4 Gyrs (significant at
the
95%CL), in the sense that bulges were significantly smaller for a
given
black hole mass. Also, the large fraction of mergers and disturbed
galaxies
(4+2 out of 20) identifies gas-rich mergers as the mechanisms
responsible
for bulge-growth. Going to higher redshift - where
evolutionary
trends should be stronger - is needed to confirm these
tantalizing
results. We propose therefore to push our investigation to
the
next suitable redshift window z=0.57 (lookback-time 6 Gyrs). Fifteen
objects
are the minimum number required to map the evolution of the
empirical
correlations between bulge properties and black-hole mass, and
to
achieve a conclusive detection of evolution (>99%CL).
WFC3/IR
11189
Probing
the Early Universe with GRBs
Cosmology
is beginning to constrain the nature of the earliest stars and
galaxies
to form in the Universe, but direct observation of galaxies at
z>6
remains highly challenging due to their scarcity, intrinsically
small
size, and high luminosity distance. GRB afterglows, thanks to
their
extreme luminosities, offer the possibility of circumventing these
normal
constraints by providing redshifts and spectral information which
couldn't
be obtained through direct observation of the host galaxies
themselves.
In addition, the association of GRBs with massive stars
means
that they are an indicator of star formation, and that their hosts
are
likely responsible for a large proportion of the ionizing radiation
during
that era. Our collaboration is conducting a campaign to rapidly
identify
and study candidate very high redshift bursts, bringing to bear
a
network of 2, 4 and 8m telescopes with near-IR instrumentation. Swift
has
proven capable of detecting faint, distant GRBs, and reporting
accurate
positions for many bursts in near real-time. Here we propose to
continue
our HST program of targeting GRBs at z~6 and above. HST is
crucial
to this endeavor, allowing us (a) to characterize the basic
properties,
such as luminosity and color, and in some cases
morphologies,
of the hosts, which is essential to understanding these
primordial
galaxies and their relationship to other galaxy populations;
and
(b) to monitor the late time afterglows and hence compare them to
lower-z
bursts and test the use of GRBs as standard candles.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
12203
- GSAcq(1,2,1) at 057/22:59:43z and REAcq(1,2,1) at 057/23:36:14z both acquired
fine lock backup on FGS 1 due to scan step limit exceeded on FGS 2
Observations possibly affected: WFC3 - 147 148, proposal ID# 11219
12204
- GSAcq(1,2,1) scheduled at 059/22:14:49z resulted in fine lock backup
(2,0,2) due to scan step limit exceeded on FGS 1.
Observations possibly affected: COS 105 - 109 proposal ID#11687,
WFC3 1 proposal ID# 11929
12205
- REAcq(1,2,1) scheduled at 060/06:09:49z required multiple attempts to
achieve Coarse Track Data Valid.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS
GSAcq
31
31
FGS
REAcq
19
19
OBAD
with Maneuver 21
21
SIGNIFICANT
EVENTS: (None)