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Daily Report #5198

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Old October 8th 10, 05:47 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report #5198

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science


PERIOD COVERED: 8pm October 6 - 7:59pm October 7, 2010 (DOY 280/00:00z-280/23:59z)


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be

HSTARS: (None)



Scheduled Successful
FGS GSAcq 11 11
FGS REAcq 07 07
OBAD with Maneuver 08 08



ACS/WFC 12209

A Strong Lensing Measurement of the Evolution of Mass Structure in
Giant Elliptical Galaxies

The structure and evolution of giant elliptical galaxies provide key
quantitative tests for the theory of hierarchical galaxy formation in
a cold dark matter dominated universe. Strong gravitational lensing
provides the only direct means for the measurement of individual
elliptical galaxy masses beyond the local universe, but there are
currently no large and homogeneous samples of strong lens galaxies at
significant cosmological look-back time. Hence, an accurate and
unambiguous measurement of the evolution of the mass-density structure
of elliptical galaxies has until now been impossible. Using
spectroscopic data from the recently initiated Baryon Oscillation
Spectroscopic Survey (BOSS) of luminous elliptical galaxies at
redshifts from approximately 0.4 to 0.7, we have identified a large
sample of high-probability strong gravitational lens candidates at
significant cosmological look-back time, based on the detection of
emission-line features from more distant galaxies along the same lines
of sight as the target ellipticals. We propose to observe 45 of these
systems with the ACS-WFC in order to confirm the incidence of lensing
and to measure the masses of the lens galaxies. We will complement
these lensing mass measurements with stellar velocity dispersions from
ground-based follow-up spectroscopy. In combination with similar data
from the Sloan Lens ACS (SLACS) Survey at lower redshifts, we will
directly measure the cosmic evolution of the ratio between lensing
mass and dynamical mass, to reveal the structural explanation for the
observed size evolution of elliptical galaxies (at high mass). We will
also measure the evolution of the logarithmic mass-density profile of
massive ellipticals, which is sensitive to the details of the merging
histories through which they are assembled. Finally, we will use our
lensing mass-to-light measurements to translate the BOSS galaxy
luminosity function into a mass function, and determine its evolution
in combination with data from the original Sloan Digital Sky Survey.

ACS/WFC 12210

SLACS for the Masses: Extending Strong Lensing to Lower Masses and
Smaller Radii

Strong gravitational lensing provides the most accurate possible
measurement of mass in the central regions of early-type galaxies
(ETGs). We propose to continue the highly productive Sloan Lens ACS
(SLACS) Survey for strong gravitational lens galaxies by observing a
substantial fraction of 135 new ETG gravitational-lens candidates with
HST-ACS WFC F814W Snapshot imaging. The proposed target sample has
been selected from the seventh and final data release of the Sloan
Digital Sky Survey, and is designed to complement the distribution of
previously confirmed SLACS lenses in lens-galaxy mass and in the ratio
of Einstein radius to optical half-light radius. The observations we
propose will lead to a combined SLACS sample covering nearly two
decades in mass, with dense mapping of enclosed mass as a function of
radius out to the half-light radius and beyond. With this longer mass
baseline, we will extend our lensing and dynamical analysis of the
mass structure and scaling relations of ETGs to galaxies of
significantly lower mass, and directly test for a transition in
structural and dark-matter content trends at intermediate galaxy mass.
The broader mass coverage will also enable us to make a direct
connection to the structure of well-studied nearby ETGs as deduced
from dynamical modeling of their line-of-sight velocity distribution
fields. Finally, the combined sample will allow a more conclusive test
of the current SLACS result that the intrinsic scatter in ETG
mass-density structure is not significantly correlated with any other
galaxy observables. The final SLACS sample at the conclusion of this
program will comprise approximately 130 lenses with known foreground
and background redshifts, and is likely to be the largest confirmed
sample of strong-lens galaxies for many years to come.


Spanning the Reionization History of IGM Helium: a Highly Efficient
Spectral Survey of the Far-UV-Brightest Quasars

The reionization of IGM helium likely occurred at redshifts of z=3 to
4. Detailed studies of HeII Ly-alpha absorption toward a handful of
quasars at 2.7z3.3 confirm the potential of such IGM probes, but the
small sample and redshift range limited confidence in cosmological
inferences. The requisite unobscured sightlines to high redshift are
extremely rare; but we've cross-correlated 10, 000 z2.8 SDSS DR7 (and
other) quasars with GALEX GR4/5, to identify 630 candidates
potentially useful for HST HeII studies. Our cycle 15-16 HST trials
confirm our approach, verifying twenty new HeII quasars at
unprecedented 40% efficiency. We propose to complete the first
efficient (80% with refinements) survey for HeII quasars, via
reconnaissance (~1 orbit) COS spectra of a highly select subset of 17
SDSS/GALEX quasars at 2.7z3.8. Along with past work, this program
will yield 3-4 of the brightest far-UV HeII sightlines within each of
10-12 redshift bins spanning 2.7z3.8, enabling a community sample
suitable for detailed spectral follow-up with HST. Herein, we will
also directly obtain quality UV spectral stacks within each redshift
bin to trace the reionization history of IGM helium; such spectral
stacks average over cosmic variance and individual object pathology.
Our high-yield HeII sightline sample and spectral stacks will enable
confident conclusions about the IGM baryon density, the spectrum and
evolution of the ionizing background, the evolution of HeII opacity,
and the epoch of helium reionization.


Spectroscopic Signatures of Binary and Recoiling Black Holes

We propose to obtain UV the spectra of the Ly-alpha and Mg II lines of
13 SDSS quasars whose H-beta lines are offset by 1000-4000 km/s from
their systemic redshifts. Such lines have been suggested to originate
in recoiling or close binary black holes. However these
interpretations are not unique and UV spectroscopy, possible only with
the HST, can discriminate between competing possibilities. Identifying
such systems is extremely important in the context of scenarios for
galaxy formation and evolution and in view of recent predictions from
numerical relativity. Close binary black holes represent an apparently
inevitable stage in the merger of two massive galaxies. The subsequent
merger of the members of the binary is expected to produce a recoiling
black hole in some fraction of cases. Thus, the census of such
systems, their environments, and hosts can constrain some of the more
uncertain parameters in evolutionary models. But before we can find
them in any numbers, we need to evaluate the candidates known so far.
This is the goal of our proposal.


How Dwarf Galaxies Got That Way: Mapping Multiphase Gaseous Halos and
Galactic Winds Below L*

One of the most vexing problems in galaxy formation concerns how gas
accretion and feedback influence the evolution of galaxies. In high
mass galaxies, numerical simulations predict the initial fuel is
accreted through 'cold' streams, after which AGN suppress star
formation to leave galaxies red and gas-poor. In the shallow potential
wells that host dwarf galaxies, gas accretion can be very efficient,
and "superwinds" driven either by hot gas expelled by SNe or momentum
imparted by SNe and hot-star radiation are regarded as the likely
source(s) of feedback. However, major doubts persist about the physics
of gas accretion, and particularly about SN-driven feedback, including
their scalings with halo mass and their influence on the evolution of
the galaxies. While "superwinds" are visible in X-rays near the point
of their departure, they generally drop below detectable
surface-brightness limits at ~ 10 kpc. Cold clumps in winds can be
detected as blue-shifted absorption against the galaxy's own
starlight, but the radial extent of these winds are difficult to
constrain, leaving their energy, momentum, and ultimate fate
uncertain. Wind prescriptions in hydrodynamical simulations are
uncertain and at present are constrained only by indirect
observations, e.g. by their influence on the stellar masses of
galaxies and IGM metallicity. All these doubts lead to one conclusion:
we do not understand gas accretion and feedback because we generally
do not observe the infall and winds directly, in the extended gaseous
halos of galaxies, when it is happening. To do this effectively, we
must harness the power of absorption-line spectroscopy to measure the
density, temperature, metallicity, and kinematics of small quantities
of diffuse gas in galaxy halos. The most important physical
diagnostics lie in the FUV, so this is uniquely a problem for HST and
COS. We propose new COS G130M and G160M observations of 41 QSOs that
probe the gaseous halos of 44 SDSS dwarf galaxies well inside their
virial radii. Using sensitive absorption-line measurements of the
multiphase gas diagnostics Lya, CII/IV, Si II/III/IV, and other
species, supplemented by optical data from SDSS and Keck, we will map
the halos of galaxies with L = 0.02 - 0.3 L*, stellar masses M* =
10^(8-10) Msun, over impact parameter from 15 - 150 kpc. These
observations will directly constrain the content and kinematics of
accreting and outflowing material, provide a concrete target for
simulations to hit, and statistically test proposed galactic superwind
models. These observations will also inform the study of galaxies at
high z, where the shallow halo potentials that host dwarf galaxies
today were the norm. These observations are low-risk and routine for
COS, easily schedulable, and promise a major advance in our
understanding of how dwarf galaxies came to be.

STIS/CCD 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 11847

CCD Bias Monitor-Part 2

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.

WFC3/IR 12283

WFC3 Infrared Spectroscopic Parallel Survey (WISP): A Survey of Star
Formation Across Cosmic Time

We will use the unique power of WFC3 slitless spectroscopy to measure
cosmic star formation across its peak epoch. The broad, continuous,
spectral coverage of the G102 and G141 grisms provides the best
currently feasible measurement of the star formation rate continuously
from 0.5z2.5, over which ground-based searches are severely limited.
Our Cycle 17 pure-parallel grism program has proven efficient for
identifying line emission from galaxies across this large fraction of
cosmic time. With less than two months of WFC3 observing completed,
our new measurements have more than doubled the sample of
emission-line galaxies that we found over the entire NICMOS Parallel
Grism program. We propose to extend this cost-effective WFC3 Survey by
using 280 orbits of pure parallel grism spectroscopy in 50 deep (4-5
orbit) fields with both G102 and G141, and 40 shallow (2-3 orbit)
fields with G141 alone. This will complete a sample of 2000-3000
emission line galaxies in the "redshift desert" and search for
serendipitous Lya emitters at z5.5.

Our primary science goals a (1) Measure ratios of bright emission
lines ([OII], [OIII], Ha, and Hb) in a substantial fraction of these
galaxies, thereby estimating dust and metallicity evolution in a
sample of galaxies that is not biased by photometric selection. (2)
Derive an extinction-corrected Ha luminosity function, with a 20 times
larger sample than our previous NICMOS results. (3) Measure the
mass-metallicity relation at crucial intermediate redshifts, with the
support of our ongoing ground-based, follow-up, observing program (4)
Determine the spectroscopic close pair fraction in this sample, in
order to constrain hierarchal merging models (5) Uncover a new sample
of obscured AGN at these redshifts and, (6) Use the Balmer break
diagnostic to constrain the ages of continuum detected sources down to
H = 25.

As a bonus, these observations will be sensitive to Lya emission at
z5.5, taking advantage of continuous spectral coverage to observe
large volumes for luminous galaxies at the highest redshifts. Over
Cycles 17 and 18, we expect to detect 5-20 LAEs over redshifts
spanning 5.5 z 7.5. These observations will likely place the most
stringent constraint on the numbers of z6.5 Lya emitters until JWST.
We are waiving all proprietary rights to our data and will make
high-level data products available through the ST/ECF.

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/IR/UV 12163

Structure and Stellar Content of the Nearest Nuclear Clusters in
Late-Type Spiral Galaxies

HST surveys have shown that nuclear star clusters are nearly
ubiquitous in late-type, bulgeless disk galaxies. In early-type
galaxies, the central black hole mass correlates with the bulge mass
and velocity dispersion, but the relationship between black hole mass
and host galaxy properties in bulgeless galaxies is not yet
understood. Some nuclear clusters (such as the one in M33) do not
contain a central massive black hole at all, while other late-type
galaxies (such as NGC 4395) are known to contain accretion-powered
active nuclei within their nuclear clusters, indicating that a central
black hole is present. But, the overall "occupation fraction" of black
holes within nuclear clusters is largely unconstrained. Measurement of
the structure, dynamics, and stellar content of nuclear star clusters
is an important pathway toward understanding the demographics of
low-mass black holes in late-type galaxies.

We propose to obtain multi-filter WFC3 UV, optical, and near-IR images
of 10 of the nearest and brightest nuclear clusters in late-type
spiral galaxies. We will use the new WFC3 data to measure the cluster
radial profiles, to search for color gradients, and in combination
with ground-based spectroscopy and stellar population modeling, to
determine the stellar masses of the clusters. Since nuclear clusters
are known to contain stellar populations with a wide range of ages,
the broad wavelength coverage of our data will provide new leverage to
constrain the star formation history of the clusters. We will carry
out dynamical modeling for the clusters, using the cluster structural
parameters and stellar M/L ratios measured from the WFC3 data and
kinematics measured from ground-based, adaptive-optics assisted
integral-field spectroscopy (already obtained or approved for 8 of the
10 targets). This will yield tight new constraints on the masses of
intermediate-mass black holes (IMBH) within the clusters, and may
result in the first dynamical detections of IMBHs in the nuclei of
late-type spirals.

WFC3/UV 12215

Searching for the Missing Low-Mass Companions of Massive Stars

Recent results on binary companions of massive O stars appear to
indicate that the distribution of secondary masses is truncated at low
masses. It thus mimics the distribution of companions of G dwarfs and
also the Initial Mass Function (IMF), except that it is shifted upward
by a factor of 20 in mass. These results, if correct, provide a
distribution of mass ratios that hints at a strong constraint on the
star-formation process. However, this intriguing result is derived
from a complex simulation of data which suffer from observational
incompleteness at the low-mass end.

We propose a snapshot survey to test this result in a very direct way.
HST WFC3 images of a sample of the nearest Cepheids (which were
formerly B stars of ~5 Msun) will search for low-mass companions down
to M dwarfs. We will confirm any companions as young stars, and thus
true physical companions, through follow-up Chandra X-ray images. Our
survey will show clearly whether the companion mass distribution is
truncated at low masses, but at a mass much higher than that of the
IMF or G dwarfs.

WFC3/UV 12245

Orbital Evolution and Stability of the Inner Uranian Moons

Nine densely-packed inner moons of Uranus show signs of chaos and
orbital instability over a variety of time scales. Many moons show
measureable orbital changes within a decade or less. Long-term
integrations predict that some moons could collide in less than one
million years. One faint ring embedded in the system may, in fact, be
the debris left behind from an earlier such collision. Meanwhile, the
nearby moon Mab falls well outside the influence of the others but
nevertheless shows rapid, as yet unexplained, changes in its orbit. It
is embedded within a dust ring that also shows surprising variability.
A highly optimized series of observations with WFC3 over the next
three cycles will address some of the fundamental open questions about
this dynamically active system: Do the orbits truly show evidence of
chaos? If so, over what time scales? What can we say about the masses
of the moons involved? What is the nature of the variations in Mab's
orbit? Is Mab's motion predictable or random? Astrometry will enable
us to derive the orbital elements of these moons with 10-km precision.
This will be sufficient to study the year-by-year changes and,
combined with other data from 2003-2007, the decadal evolution of the
orbits. The pairing of precise astrometry with numerical integrations
will enable us to derive new dynamical constraints on the masses of
these moons. Mass is the fundamental unknown quantity currently
limiting our ability to reproduce the interactions within this system.
This program will also capitalize upon our best opportunity for nearly
40 years to study the unexplained variations in Uranus's faint outer

WFC3/UV 12324

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.

WFC3/UV 12345

UVIS Long Darks Test

Darks during SMOV showed a systematically lower global dark rate as
well as lower scatter when compared to the Cycle 17 darks. Those two
sets of exposures differ in exposure time - 1800 sec during SMOV and
900 sec during Cycle 17. Hypothetically, the effect could be caused by
short-duration stray light, say ~500-sec in duration. During the
latter part of Cycle 17, operation of WFC3 was changed to additionally
block the light path to the detector with the CSM. This program
acquires a small number of darks at the longer SMOV exposure times
(1800 sec) in order to check whether the effect repeats in the new
operating mode.

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).

Old July 28th 11, 08:07 AM
jiefu jiefu is offline
First recorded activity by SpaceBanter: Jul 2011
Posts: 5

6.Thank you for this article. Thatís all I can say. You most definitely have made this blog into something special. You clearly know what you are doing, youíve covered so many bases.Thanks!
Old August 18th 11, 01:51 PM
LowellBooth LowellBooth is offline
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First recorded activity by SpaceBanter: Aug 2011
Location: US
Posts: 1

Originally Posted by jiefu View Post
6.Thank you for this article. Thatís all I can say. You most definitely have made this blog into something special. You clearly know what you are doing, youíve covered so many bases.Thanks!

Many infomations but very long to read !

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