NASA Hubble Space Telescope Daily Report #4417

Notice: Due to the conversion of some ACS WFC or HRC observations into WFPC2, or NICMOS observations after the loss of ACS CCD science capability in January, there may be an occasional discrepancy between a proposal’s listed (and correct) instrument usage and the abstract that follows it.

HUBBLE SPACE TELESCOPE DAILY REPORT # 4417

– Continuing to collect World Class Science

PERIOD COVERED: UT August 1, 2007 (DOY 213)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration – CR Persistence Part 5

A new procedure proposed to alleviate the CR-persistence problem of NICMOS. Dark frames will be obtained immediately upon exiting the SAA contour 23, and every time a NICMOS exposure is scheduled within 50 minutes of coming out of the SAA. The darks will be obtained in parallel in all three NICMOS Cameras. The POST-SAA darks will be non-standard reference files available to users with a USEAFTER date/time mark. The keyword ‘USEAFTER=3Ddate/time’ will also be added to the header of each POST-SAA DARK frame. The keyword must be populated with the time, in addition to the date, because HST crosses the SAA ~8 times per day so each POST-SAA DARK will need to have the appropriate time specified, for users to identify the ones they need. Both the raw and processed images will be archived as POST-SAA DARKSs. Generally we expect that all NICMOS science/calibration observations started within 50 minutes of leaving an SAA will need such maps to remove the CR persistence from the science images. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors.

NIC2 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=3D0.36 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=3D0.57 {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}.

WFPC2 11027

Visible Earth Flats

This proposal monitors flatfield stability. This proposal obtains sequences of Earth streak flats to construct high quality flat fields for the WFPC2 filter set. These flat fields will allow mapping of the OTA illumination pattern and will be used in conjuction with previous internal and external flats to generate new pipeline superflats. These Earth flats will complement the Earth flat data obtained during cycles 4-14.

WFPC2 11029

WFPC2 CYCLE 15 Intflat Linearity Check and Filter Rotation Anomaly Monitor

Intflat observations will be taken to provide a linearity check: the linearity test consists of a series of intflats in F555W, in each gain and each shutter. A combination of intflats, visflats, and earthflats will be used to check the repeatability of filter wheel motions. {Intflat sequences tied to decons, visits 1-18 in prop 10363, have been moved to the cycle 15 decon proposal xxxx for easier scheduling.} Note: long-exposure WFPC2 intflats must be scheduled during ACS anneals to prevent stray light from the WFPC2 lamps from contaminating long ACS external exposures.

WFPC2 11084

Probing the Least Luminous Galaxies in the Local Universe

We propose to obtain deep color-magnitude data of eight new Local Group galaxies which we recently discovered: Andromeda XI, Andromeda XII, and Andromeda XIII {satellites of M31}; Canes Venatici I, Canes Venatici II, Hercules, and Leo IV {satellites of the Milky Way}; and Leo T, a new “free-floating” Local Group dwarf spheroidal with evidence for recent star formation and associated H I gas. These represent the least luminous galaxies known at *any* redshift, and are the only accessible laboratories for studying this extreme regime of galaxy formation. With deep WFPC-2 F606W and F814W pointings at their centers, we will determine whether these objects contain single or multiple age stellar populations, as well as whether these objects display a range of metallicities.

WFPC2 11100

Two new `bullets’ for MOND: revealing the properties of dark matter in massive merging clusters

The principal objective of this proposal is to study the physical nature of dark matter by using two, massive, newly-identified merging clusters of galaxies. As shown by the pioneering example of the “bullet cluster” {1E0657-56}, such systems are ideal laboratories for detecting dark matter and distinguishing between cold dark matter {CDM} and other scenarios {e.g. self- interacting dark matter}. Our limit on the self-interaction cross-section of dark matter relies on the assumption of a normal pre-merger mass-to-light ratios, and a small impact parameter during the collision of the two clusters. In order to mitigate any possible systematic effects, it is vital to extend this work to other, similar systems. With detailed observations of new systems, the systematic uncertainties in the dark matter cross section calculations can be improved substantially, allowing us to move from rough order of magnitude estimates to measurements with quantifiable uncertainties that can be compared usefully with the predictions from numerical simulations. Our targets are two extraordinary, high-redshift, merging galaxy clusters recently discovered by the Massive Cluster Survey {MACS}. This survey is by far the best matched to this study, since it selects medium redshift {optimal for gravitational lensing studies} and X-ray luminous {hence massive} objects. We have selected the best candidates with clear evidence for considerable offsets between the hot X-ray emitting gas and optically luminous stellar material. The two most striking examples are the targets of this proposal. To pin down the position of the dark matter component we require high resolution, absolutely calibrated mass maps. The combination of weak and strong lensing measurements is needed to attain this goal. This can only be achieved with the excellent resolving power of the HST {in combination with wide-field, multicolor Subaru data already in hand}. We therefore request multicolor HST/WFPC2 observations of the two merging clusters. The combination of constraints from multiply lensed images {identified via morphology and color information} and high-resolution weak lensing data will allow us to construct, self-consistently, their mass distribution from the very centers to the outskirts. Gravitational lensing thus provides a unique tool transforming these clusters into dark matter laboratories. They will supply us with answers as to the nature and properties of dark matter, and how it shapes galaxies and galaxy clusters and their evolution through cosmic time.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens a window into dynamical conditions in the protoplanetary disk where they formed as well as the history of subsequent events which sculpted the outer Solar System and emplaced them onto their present day heliocentric orbits. To date, at least 47 TNBs have been discovered, but only about a dozen have had their mutual orbits and separate colors determined, frustrating their use to investigate numerous important scientific questions. The current shortage of data especially cripples scientific investigations requiring statistical comparisons among the ensemble characteristics. We propose to obtain sufficient astrometry and photometry of 23 TNBs to compute their mutual orbits and system masses and to determine separate primary and secondary colors, roughly tripling the sample for which this information is known, as well as extending it to include systems of two near-equal size bodies. To make the most efficient possible use of HST, we will use a Monte Carlo technique to optimally schedule our observations.

WFPC2 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still largely an open problem in cosmology: how does the Universe evolve from large linear scales dominated by dark matter to the highly non-linear scales of galaxies, where baryons and dark matter both play important, interacting, roles? To understand the complex physical processes involved in their formation scenario, and why they have the tight scaling relations that we observe today {e.g. the Fundamental Plane}, it is critically important not only to undertstand their stellar structure, but also their dark-matter distribution from the smallest to the largest scales. Over the last three years the SLACS collaboration has developed a toolbox to tackle these issues in a unique and encompassing way by combining new non-parametric strong lensing techniques, stellar dynamics, and most recently weak gravitational lensing, with high-quality Hubble Space Telescope imaging and VLT/Keck spectroscopic data of early-type lens systems. This allows us to break degeneracies that are inherent to each of these techniques seperately and probe the mass structure of early-type galaxies from 0.1 to 100 effective radii. The large dynamic range to which lensing is sentive allows us both to probe the clumpy substructure of these galaxies, as well as their low-density outer haloes. These methods have convincingly been demonstrated, by our team, using smaller pilot-samples of SLACS lens systems with HST data. In this proposal, we request observing time with WFPC2 and NICMOS to observe 53 strong lens systems from SLACS, to obtain complete multi-color imaging for each system. This would bring the total number of SLACS lens systems to 87 with completed HST imaging and effectively doubles the known number of galaxy-scale strong lenses. The deep HST images enable us to fully exploit our new techniques, beat down low-number statistics, and probe the structure and evolution of early- type galaxies, not only with a uniform data-set an order of magnitude larger than what is available now, but also with a fully coherent and self-consistent methodological approach!

WFPC2/NIC3 11188

First Resolved Imaging of Escaping Lyman Continuum

The emission from star-forming galaxies appears to be responsible for reionization of the universe at z>6. However, the models that attempt to describe the detailed impact of high- redshift galaxies on the surrounding inter-galactic medium {IGM} are strongly dependent upon several uncertain parameters. Perhaps the most uncertain is the fraction of HI-ionizing photons produced by young stars which escape into the IGM. Most attempts to measure this “escape fraction” {f_esc} have produced null results. Recently, a small subset of z~3 Lyman Break Galaxies {LBGs} has been found exhibiting large escape fractions. It remains unclear however, what differentiates them from other LBGs. Several models attempt to explain how such a large fraction of ionizing continuum can escape through the HI and dust in the ISM {eg. “chimneys” created by SNe winds, globular cluster formation, etc.}, each producing unique signatures which can be observed with resolved imaging of the escaping Lyman continuum. We propose a deep, high resolution WFPC2 image of the ionizing continuum {F336W} and the rest-frame 1500 Angstrom continuum {F606W} of five of the six known LBGs with large escape fractions. These LBGs all fit within a single WFPC2 pointing, yielding high observing efficiency. Additionally, they all have z~3.1 or higher, the optimal redshift range for probing the Lyman Continuum region with available WFPC2 filters. These factors make our proposed sample especially suitable for follow- up. With these data we will discern the mechanisms responsible for producing large escape fractions, and therefore gain insight into the process of reionization.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: None

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL

FGS GSacq               07                 07
FGS REacq               08                 08
OBAD with Maneuver      30                 30

SIGNIFICANT EVENTS: (None)