HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4770
PERIOD COVERED: 5am January 12 - 5am January 13, 2009 (DOY
012/1000z-013/1000z)
OBSERVATIONS SCHEDULED
NIC3 11236
Did Rare, Large Escape-Fraction Galaxies Reionize the
Universe?
Lyman continuum photons produced in massive starbursts may
have played a
dominant role in the reionization of the Universe.
Starbursts are
important contributors to the ionizing metagalactic
background at lower
redshifts as well. However, their contribution to the
background depends
upon the fraction of ionizing radiation that escapes from
the intrinsic
opacity of galaxies below the Lyman limit. Current surveys
suggest that
the escape fraction is close to zero in most galaxies,
even among young
starbursts, but is large in 15-25% of them. Non-uniform
escape fractions
are expected as a result of violent events creating clear
paths in small
parts of galaxies. The number of galaxies observed with
high escape
fraction will result from the combination of the intrinsic
number with
clear lines of sight and their orientation with respect to
the observer.
We propose to measure the fraction of escaping Lyman
continuum radiation
in a large sample (47) of z~0.7 starbursts in the COSMOS
field. These
compact UV-luminous galaxies are good analogs to high
redshift LBGs.
Using the SBC/PR130L we can quickly (1-4 orbits) detect
relative escape
fractions (f_LC/f_1500) of 25% or more. This will be the
first
measurement of the escape fraction in sources between z=1
and the local
universe. We expect ~10 detections. Stacking will set
limits of <4% on
the relative escape fraction in the rest. We will
correlate the LC
detections with the properties of the galaxies. By
targeting z~0.7 in
COSMOS, we will have tremendous ancillary information on
those sources.
A non-detection in all sources would be significant (99%
confidence).
This would imply that QSOs provide the overwhelming
majority of ionizing
radiation at z<1, requiring substantial evolution in
the processes
within Lyman break galaxies which allow large escape
fractions at high
redshift.
WFPC2 11130
AGNs with Intermediate-mass Black Holes: Testing the Black
Hole-Bulge
Paradigm, Part II
The recent progress in the study of central black holes in
galactic
nuclei has led to a general consensus that supermassive
{10^6-10^9 solar
mass} black holes are closely connected with the formation
and
evolutionary history of large galaxies, especially their
bulge
component. Two outstanding issues, however, remain
unresolved. Can
central black holes form in the absence of a bulge? And
does the mass
function of central black holes extend below 10^6 solar
masses?
Intermediate-mass black holes {<10^6 solar masses}, if
they exist, may
offer important clues to the nature of the seeds of
supermassive black
holes. Using the SDSS, our group has successfully
uncovered a new
population of AGNs with intermediate-mass black holes that
reside in
low-luminosity galaxies. However, very little is known
about the
detailed morphologies or structural parameters of the host
galaxies
themselves, including the crucial question of whether they
have bulges
or not. Surprisingly, the majority of the targets of our
Cycle 14 pilot
program have structural properties similar to dwarf
elliptical galaxies.
The statistics from this initial study, however, are
really too sparse
to reach definitive conclusions on this important new
class of black
holes. We wish to extend this study to a larger sample, by
using the
Snapshot mode to obtain WFPC2 F814W images from a parent
sample of 175
AGNs with intermediate- mass black holes selected from our
final SDSS
search. We are particularly keen to determine whether the
hosts contain
bulges, and if so, how the fundamental plane properties of
the host
depend on the mass of their central black holes. We will
also
investigate the environment of this unique class of AGNs.
WFPC2 11302
WFPC2 CYCLE 16 Standard Darks - Part III
This dark calibration program obtains dark frames every
week in order to
provide data for the ongoing calibration of the CCD dark
current rate,
and to monitor and characterize the evolution of hot
pixels. Over an
extended period these data will also provide a monitor of
radiation
damage to the CCDs.
WFPC2 11327
Red Leaks
The aim of this program is to measure the red leaks in the
8 WFPC2 UV???
filters (F122M, F300W, F255W, F218W, F185W, F170W, F160BW,
F122M). We
will use red crossing filters to isolate and directly
measure the leaks.
No observations of this kind have ever been performed with
WFPC2 to
check the red leaks in the UV filters, most of them being
extensively
used by GO/GTO programs. A previous calibration program
has only imaged
spectrophotometric standard stars with UV filters (no
filter crossing)
thus the red leak is hard to measure using this data. The
throughput
curves for some of the UV filters (F300W, F255W, F218W,
F185W) in
synphot have incomplete information, some of them have
gaps in the
measurements as wide as 3000A.
WFPC2 11793
WFPC2 Cycle 16 Internal Monitor
This calibration proposal is the Cycle 15 routine internal
monitor for
WFPC2, to be run weekly to monitor the health of the
cameras. A variety
of internal exposures are obtained in order to provide a
monitor of the
integrity of the CCD camera electronics in both bays (both
gain 7 and
gain 15 -- to test stability of gains and bias levels), a
test for
quantum efficiency in the CCDs, and a monitor for possible
buildup of
contaminants on the CCD windows. These also provide raw
data for
generating annual super-bias reference files for the
calibration
pipeline.
WFPC2 11944
Binaries at the Extremes of the H-R Diagram
We propose to use HST/Fine Guidance Sensor 1r to survey
for binaries
among some of the most massive, least massive, and oldest
stars in our
part of the Galaxy. FGS allows us to spatially resolve
binary systems
that are too faint to observe using ground-based, speckle
or optical
long baseline interferometry, and too close to resolve
with AO. We
propose a SNAP-style program of single orbit FGS TRANS
mode observations
of very massive stars in the cluster NGC 3603, luminous
blue variables,
nearby low mass main sequence stars, cool subdwarf stars,
and white
dwarfs. These observations will help us to (1) identify
systems suitable
for follow up studies for mass determination, (2) study
the role of
binaries in stellar birth and in advanced evolutionary
states, (3)
explore the fundamental properties of stars near the main
sequence-brown
dwarf boundary, (4) understand the role of binaries for
X-ray bright
systems, (5) find binaries among ancient and nearby
subdwarf stars, and
(6) help calibrate the white dwarf mass - radius relation.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary
reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
11637 - GSAcq(2,3,2) acquisition scheduled at 012/17:39:06
- 17:47:11
failed to RGA Hold due to (QF2STOPF) stop flag indication on FGS-2.
Observations affected: Astrometry Proposal ID#11944.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq
08
07
FGS
REacq 05
05
OBAD with Maneuver
26
26
SIGNIFICANT EVENTS: (None)