HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 4223
PERIOD COVERED: UT October 19, 2006 (DOY 292)
OBSERVATIONS SCHEDULED
ACS/WFC 10816
The Formation History of Andromeda's Extended Metal-Poor Halo
We propose deep ACS imaging in the outer spheroid of the Andromeda
galaxy, in order to measure the star formation history of its true
halo.
For the past 20 years, nearly all studies of the Andromeda
"halo" were
focused on the spheroid within 30 kpc of the galaxy's center, a
region
now known to host significant substructure and populations with high
metallicity and intermediate ages. However, two groups have recently
discovered an extended metal-poor halo beyond 30 kpc; this population
is
distinct in its surface-brightness profile, abundance distribution,
and
kinematics. In earlier cycles, we obtained deep images of the inner
spheroid {11 kpc on the minor axis}, outer disk {25 kpc on the major
axis}, and giant tidal stream, yielding the complete star formation
history in each field. We now propose deep ACS imaging of 4 fields
bracketing this 30 kpc transition point in the spheroid, so that the
inner spheroid and the extended halo populations can be
disentangled,
enabling a reconstruction of the star formation history in the halo.
A
wide age distribution in the halo, as found in the inner spheroid,
would
imply the halo was assembled through ongoing accretion of satellite
galaxies, while a uniformly old population would be a strong
indication
that the halo was formed during the early rapid collapse of the
Andromeda proto-galaxy.
ACS/WFC 10880
The host galaxies of QSO2s: AGN feeding and evolution at high
luminosities
Now that the presence of supermassive black holes in the nuclei of
galaxies is a well established fact, other questions related to the
AGN
phenomena still have to be answered. Problems of particular interest
are
how the AGN gets fed, how the black hole evolves and how the
evolution
of the black hole is related to the evolution of the galaxy bulge.
Here
we propose to address some of these issues using ACS/WFC + F775W
snapshot images of 73 QSO2s with redshifts in the range 0.3<z<0.4.
These
observations will be combined with similar archival data of QSO1s
and
ground based data of Seyfert and normal galaxies. First, we will
intestigate whether interactions are the most important feeding
mechanism in high luminosity AGNs. This will be done in a
quantitative
way, comparing the asymmetry indices of QSO2 hosts with those of
lower
luminosity AGNs and normal galaxies. Second, we will do a detailed
study
of the morphology of the host galaxies of both QSO types, to
determine
if they are similar, or if there is an evolutionary trend from QSO2s
to
QSO1s. The results from this project will represent an important step
in
the understanding of AGN evolution, and may also introduce a
substantial
modification to the Unified Model.
ACS/WFC 10881
The Ultimate Gravitational Lensing Survey of Cluster Mass and
Substructure
We propose a systematic and detailed investigation of the mass,
substructure, and thermodynamics of one hundred X-ray luminous
galaxy
clusters at 0.15<z<0.3. The primary goal is to test our recent
suggestion that this population is dominated by dynamically immature
disturbed clusters, and that the observed mass-temperature relation
suffers strong structural segregation. If confirmed, this would
represent a paradigm shift in our observational understanding of
clusters, that were hitherto believed to be dominated by mature,
undisturbed systems. The key observation to this endeavor is Hubble
imaging of cluster cores to identify robustly tangential and radial
multiple arcs and measure the shape of faint galaxies. These strong
and
weak lensing signals will give an accurate measure of the total mass
and
structure of the dark matter distribution that we will subsequently
compare with X-ray and Sunyaev Zeldovich Effect observables. The
broader
applications of our project include 1} the calibration of
mass-temperature and mass-SZE scaling relations which will be
critical
for the calibration of proposed dark energy experiments, and 2} the
low
redshift baseline study of the demographics of massive clusters to
aid
interpretation of future high redshift {z>1} cluster samples. For
this
ultimate cluster survey, we request ACS SNAPSHOTS through the F606W
filter drawn from a target list of 143 clusters.
ACS/WFC 10886
The Sloan Lens ACS Survey: Towards 100 New Strong Lenses
As a continuation of the highly successful Sloan Lens ACS {SLACS}
Survey
for new strong gravitational lenses, we propose one orbit of ACS-WFC
F814W imaging for each of 50 high- probability strong galaxy-galaxy
lens
candidates. These observations will confirm new lens systems and
permit
immediate and accurate photometry, shape measurement, and mass
modeling
of the lens galaxies. The lenses delivered by the SLACS Survey all
show
extended source structure, furnishing more constraints on the
projected
lens potential than lensed-quasar image positions. In addition,
SLACS
lenses have lens galaxies that are much brighter than their lensed
sources, facilitating detailed photometric and dynamical observation
of
the former. When confirmed lenses from this proposal are combined
with
lenses discovered by SLACS in Cycles 13 and 14, we expect the final
SLACS lens sample to number 80--100: an approximate doubling of the
number of known galaxy-scale strong gravitational lenses and an
order-of-magnitude increase in the number of optical Einstein rings.
By
virtue of its homogeneous selection and sheer size, the SLACS sample
will allow an unprecedented exploration of the mass structure of the
early-type galaxy population as a function of all other observable
quantities. This new sample will be a valuable resource to the
astronomical community by enabling qualitatively new strong lensing
science, and as such we will waive all but a short {3-month}
proprietary
period on the observations.
ACS/WFC 10917
Afterglows and Environments of Short-Hard Gamma-Ray Bursts
Discovery of the first afterglows of short-hard bursts {SHBs} has led
to
a revolution in our understanding of these events, strongly
suggesting
that they originate in the mergers of compact-object binaries.
Capitalizing on this progress, we propose to pursue the next
generation
of SHB observations with HST, tracking the decay of all accessible
SHB
afterglows to late times and pinpointing the location of several
more
within the context of their host galaxies. These observations will
allow
quantitative analysis of progenitor lifetimes and short burst
environments, enable direct confrontation with population synthesis
models, and provide updated event rate estimates for the LIGO and
VIRGO
gravitational-wave detectors that are now coming on-line.
NIC2 10825
The Formation Epoch of Early-type Galaxies: Constraints from the
Fundamental Plane at z=1.3
Field and cluster surveys both show a ~50% decrease in the number of
early-type galaxies at redshifts near 1. Galaxies that have either
recently transformed into early-types or undergone star formation
should
have younger appearing stellar populations. The resulting change in
the
mass-to-light ratio can be detected by the offset in the fundamental
plane with redshift. We will use the fundamental plane to test whether
a
significant fraction of early-type galaxies have evidence of recent
star
formation, using a sample of ~20 z=1.3 cluster and field early-type
galaxies. This is 7 times larger than the sample previously used at
this
redshift. We already have the high signal-to-noise 12-20 hour long
Keck
spectra for these galaxies we need for velocity dispersions. To use
the
fundamental plane, we require sizes and surface brightnesses. We
propose
12 orbits of NICMOS Camera 2 imaging to measure the sizes and
surface
brightness distributions of these objects in a rest-frame optical
passband. These data will provide high quality surface brightness
profiles out two ~2 half-light radii, at wavelengths comparable to
previous fundamental plane studies. When combined with our spectra,
the
HST data will establish the mass-to-light ratio evolution for
massive
early-type galaxies from the fundamental plane. We will define the
epoch
of last star formation for these z=1.3 galaxies, directly testing
the
claims of strong evolution at z=1.
WFPC2 10744
WFPC2 Cycle 14 Decontaminations and Associated Observations
This proposal is for the WFPC2 decontamination. Also included are
instrument monitors tied to decontamination: photometric stability
check, focus monitor, pre- and post-decontamination internals {bias,
intflats, kspots, & darks}, UV throughput check, VISFLAT sweep,
and
internal UV flat check.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary
reports
of potential non-nominal performance that will be investigated.)
HSTARS:
10473 - GSACQ(2,1,2) failed, Search Radius Limit Exceeded on FGS 2
GSACQ(2,1,2) at 292/09:21:02 failed due to Search Radius Limit
Exceeded
on FGS 2 at 09:26:22. OBAD data prior to GSACQ showed RSS attitude
correction of 11.71 arcseconds, OBAD map after GSACQ failure showed
RSS
error of 1.83 arcseconds.
REAcq (2,1,2) at 292.10:54:20 failed due to Search Radius Limit
Exceeded
on FGS 2 at 10:58:59.
OBAD #1: RSS = 812.99
OBAD #2: RSS = 8.84
OBAD MAP: RSS = 8.44
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
08
07
FGS
REacq
08
07
OBAD with Maneuver
32
32
SIGNIFICANT EVENTS: (None)
Joe L. Cooper
Office: 301 286-6970
Home: 301 490-2449
Mobile: 410 299-8123
Home E-mail: joecooper81@comcast.net
Work E-mail:
jcooper@hst.nasa.gov