NASA Hubble Space Telescope Daily Report #4113
HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science
DAILY REPORT # 4113
PERIOD COVERED: UT May 12,13,14, 2006 (DOY 132,133,134)
OBSERVATIONS SCHEDULED
ACS/WFC 10775
An ACS Survey of Galactic Globular Clusters
We propose to conduct an ACS/WFC imaging survey of Galactic globular clusters. We will construct the most extensive and deepest set of photometry and astrometry to-date for these systems reaching a main sequence mass of ~0.2 solar mass with S/N >= 10. We will combine these data with archival WFPC2 and STIS images to determine proper motions for the stars in our fields. The resultant cleaned cluster CMDs will allow us to study a variety of scientific questions. These include [but are not limited to] 1} the determination of cluster ages and distances 2} the construction of main sequence mass functions and the issue of mass segregation 3} the internal motions and dynamical evolution of globular clusters, and 4} absolute cluster motions, orbits, and the Milky Way gravitational potential. We anticipate that the unique resource provided by the proposed treasury archive will play a central role in the field of globular cluster studies for decades, with a stature comparable to that of the Hubble Deep Field for high redshift studies.
ACS/HRC/WFC 10758
ACS CCDs daily monitor
This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. Changes from cycle 13:- The default gain for WFC is 2 e-/DN. As before bias frames will be collected for both gain 1 and gain 2. Dark frames are acquired using the default gain {2}. This program cover the period May, 31 2006- Oct, 1-2006. The first half of the program has a different proposal number: 10729.
WFPC2 10744
WFPC2 Cycle 14 Decontaminations and Associated Observations
This proposal is for the WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check.
ACS/WFC 10742
Ramp Filter and Grism Zeroth Order Wavelengths
A calibration of ramp filters on the ACS is obtained through crossing the ramp filters with the G800L grism in observations of the standard star GD 153. The standard star is also observed through the F606W filter and each ramp crossed with a wide-band filter to measure any filter- wedge offset from the standard grism calibration produced by crossing a ramp with the grism. The ramp filters chosen for this first calibration are those which have been used most extensively by observers during the past ACS cycles and can be usefully crossed with the G800L grism.
ACS/WFC 10630
The Fine Structure of Elliptical Galaxies in Voids
Elliptical galaxies constitute a remarkably homogeneous class of objects with a tight color- magnitude relation and a well-defined Fundamental Plane. In spite of their bland and symmetrical morphology, they are characterized by a wealth of structural features {such as nuclear disks, dust lanes, shells, blue cores, etc.} which contain important clues to their formation history. Little is known about how and if these sub-structures vary as a function of environment; in fact, due to the morphology density relation, our knowledge of ellipticals is strongly biased towards overdense regions such as clusters. But what of the fine structure of ellipticals in voids? According to theoretical predictions, void galaxies should have different merger histories than those in clusters, which may imply that their fine structure also differs. We address these issues using the exquisite angular resolution of HST/ACS to resolve sub-structures in the most accurately classified sample, to date, of truly isolated ellipticals, identified using the 2dFGRS.
ACS/WFC 10626
A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to z = 0.9
We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy clusters at 0.3 < z < 0.9 from the Red Sequence Cluster Survey {RCS}. An examination of the galaxian light in the brightest cluster galaxies, coupled with a statistical analysis of the strong-lensing properties of the sample, will allow us to contrain the evolution of both the baryonic and dark mass in cluster cores, over an unprecedented redshift range and sample size. In detail, we will use the high- resolution ACS images to measure the metric {10 kpc/h} luminosity and morphological disturbances around the brightest clusters galaxies, in order to calibrate their accretion history in comparison to recent detailed simulations of structure formation in cluster cores. These images will also yield a well-defined sample of arcs formed by strong lensing by these clusters; the frequency and detailed distribution {size, multiplicity, redshifts} of these strong lens systems sets strong constraints on the total mass content {and its structure} in the centers of the clusters. These data will also be invaluable in the study of the morphological evolution and properties of cluster galaxies over a significant redshift range. These analyses will be supported by extensive ongoing optical and near-infrared imaging, and optical spectroscopy at Magellan, VLT and Gemini telescopes, as well as host of smaller facilities.
ACS/WFC 10596
AGNs with Intermediate-mass Black Holes: A Test of the Black Hole-Bulge Paradigm
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 {10^4-10^6 solar masses}, if they exist, may offer important clues to the nature of the seeds of supermassive black holes. In a first systematic search using the Sloan Digital Sky Survey, we have recently discovered 19 Type 1 AGNs with candidate intermediate-mass black holes that reside in low-luminosity, presumably late-type host galaxies. Follow-up observations with Keck indicate that these objects obey the low-mass extension of the well-known correlation between black hole mass and bulge stellar velocity dispersion. However, very little is known about the host galaxies themselves, including the crucial question of whether they have bulges or not. We propose to obtain ACS/WFC images of this unique sample of AGNs in order to investigate the detailed structural properties of the host galaxies. We are particularly keen to determine whether the hosts contain bulges, and if so, where they lie on the fundamental plane of spheroids compared to the bulges of supermassive black holes. We will also be able to measure an accurate optical luminosity for the AGN, which is an essential ingredient to improve the current mass estimates.
ACS/HRC/WFC 10575
Lyman alpha morphology of local starburst galaxies
Our pilot imaging study of 6 local galaxies using ACS/SBC in the cosmologically important Lyman- alpha line has begun to reveal intriguing results. Here we propse ACS/HRC imaging of this sample, the approval of the which will allow for a significant increase in the impact of the original study and extend the limits of current understanding of Lyman-alpha escape. With this data we can accurately calibrate our Lyman-alpha line-only images and explore for the first time Lyman- alpha fluxes and equivalent widths in spatially resolved systems. These data would also allow us to test the current models of Lyman-alpha escape mechanisms and investigate possible correlations between Lyman-alpha emission and other local parameters such as age and internal reddening. The addition of high-resolution H-alpha data allows us to quantitatively study the decoupling of Lyman-alpha from non-resonant radiation and spatially explore the destruction and attenuation of Lyman-alpha. The study will go a long way towards resolving the outstanding issues complicating the interpretation of high redshift studies and the use of Lyman-alpha to quantitatively study the distant universe.
ACS/HRC 10564
Resolving Ultracool White Dwarf Binaries
We propose an ACS/HRC imaging survey of the coolest white dwarfs known in order to search for binarity. Current models fail to match observed spectral energy distributions of these sub- 4000K stellar remnants, consistently predicting much lower luminosities than observed. A possible explanation is that they are binary in nature. Because these cool degenerates have no spectral features, the only way to investigate their apparent overluminosity is with very high resolution imaging, which can only be done with HST {these stars are far too faint to be observed with adaptive optics on the ground}. Optical wavelengths are ideal because the spectral energy distributions of these old degenerates peak near 600 nm. With the F435W filter we will be able to partially resolve equally luminous binaries as close as 0.02″, which corresponds to within 0.6 AU for over half of the 12 proposed target stars. The collected data will be critical in determining whether these stars represent the oldest white dwarfs in the solar neighborhood.
ACS/HRC 10563
Accurate dark-matter mass profiles in 3 elliptical galaxies as a test of CDM
A critical test of the successful Lambda-CDM picture for structure formation is the measurement of the power law exponent, gamma, of the centre of dark matter density profiles, predicted to lie in the range 1.0-1.5. Measurements of gamma derived from rotation curves of LSB galaxies appear to contradict CDM, but rely on assumptions that are difficult to verify {e.g. axisymmetry}. We have recently demonstrated, using our new `semi-linear’ inversion method, how strong gravitational lensing by galaxies can provide a clean and accurate measurement of gamma, free of such ambiguities. HST images of lensed non-AGN galaxies provide hundreds of resolution elements, each a constraint on the mass profile. Such lenses are exceedingly rare, but we have recently discovered new systems. We propose deep ACS-HRC observations of 3 systems to measure gamma in each, accurate to 0.15 {95% confidence} and to obtain an indication of its variation between galaxies. To establish the required number of orbits we have undertaken an end-to-end simulation of the problem, creating and analysing synthetic ACS images. Additionally the semi-linear method simultaneously reconstructs the pixelised source surface brightness distribution. Our simulations demonstrate that the fine sampling and small pixel scattering of the HRC, resolves the morphology of the sources with exquisite detail.
ACS/HRC 10556
Neutral Gas at Redshift z=0.5
Damped Lyman-alpha systems {DLAs} are used to track the bulk of the neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy, they could only be studied from the ground at redshifts z>1.65. However, HST has now permitted us to discover 41 DLAs at z<1.65 in our previous surveys. Followup studies of these systems are providing a wealth of information about the evolution of the neutral gas phase component of the Universe. But one problem is that these 41 low-redshift systems are spread over a wide range of redshifts spanning nearly 70% of the age of the Universe. Consequently, past surveys for low-redshift DLAs have not been able to offer very good precision in any small redshift regime. Here we propose an ACS-HRC- PR200L spectroscopic survey in the redshift interval z=[0.37, 0.7] which we estimate will permit us to discover another 41 DLAs. This will not only allow us to double the number of low-redshift DLAs, but it will also provide a relatively high-precision regime in the low-redshift Universe that can be used to anchor evolutionary studies. Fortunately DLAs have high absorption equivalent width, so ACS-HRC-PR200L has high-enough resoultion to perform this proposed MgII-selected DLA survey.
ACS/SBC 10554
Globular Cluster Systems of Elliptical Galaxies in Low Density Environments
We propose to use the ACS/WFC to determine colour {metallicity} distributions and luminosity functions for the globular cluster populations in a well-defined sample of elliptical galaxies in low- density environments, and to compare the results with similar samples taken from a rich cluster environment. Low-luminosity ellipticals are now recognized to play a pivotal role in testing hierarchical models of galaxy formation, and their globular cluster populations provide a unique probe of their star formation and metal enrichment history. The data will be used to {i} determine whether the bimodal colour distributions indicative of multiple formation epochs in luminous ellipticals are also prevalent in low-luminosity field ellipticals; {ii} place joint constraints on age and metallicity in systems with more than one population and determine the spread of ages in any one system; {iii} test whether cluster destruction processes {e.g. tidal shocking} are more effective in low-luminosity ellipticals, as predicted from their higher mass densities. ACS observations are essential to eliminate foreground/background contamination and to probe deep into the luminosity function to obtain a good statistical sample of clusters. The TAC has previously awarded HST time to two large surveys of globular cluster systems in rich cluster environments, but there is currently no comparable survey in low-density environments with which to compare these results.
ACS/HRC/WFC 10548
Near-UV Snapshot Survey of Low Luminosity AGNs
Low-luminosity active galactic nuclei {LLAGNs} comprise ~30% of all bright galaxies {B<12.5} and are the most common type of AGN. These include low-luminosity Seyfert galaxies, LINERs, and transition-type objects {TOs, also called weak-[OI] LINERs}. What powers them is still at the forefront of AGN research. To unveil the nature of the central source we propose a near-UV snapshot survey of 50 nearby LLAGNs using ACS/HRC and the filter {F330W}, a configuration which is optimal to detect faint star forming regions around their nuclei. These images will complement optical and near-IR images available in the HST archive, providing a panchromatic atlas of the inner regions of these galaxies, which will be used to study their nuclear stellar population. Our main goals are to: 1} Investigate the presence of nuclear unresolved sources that can be attributed to an AGN; 2} Determine the frequency of nuclear and circumnuclear stellar clusters, and whether they are more common in Transition Objects {TOs} than in LINERs; 3} Characterize the sizes, colors, luminosities, masses and ages of these clusters; 4} Derive the luminosity function of star clusters and study their evaporation over time in the vicinity of AGNs. Finally, the results of this project will be combined with those of a previous similar one for Seyfert galaxies in order to compare the nature of the nuclear sources and investigate if there could be an evolution from Seyferts to TOs and LINERs. By adding UV images to the existing optical and near-IR ones, this project will also create an extremely valuable database for astronomers with a broad range of scientific interests.
ACS/WFC 10503
The Star Formation Histories of Early Type Dwarf Galaxies in Low Density Environments: Clues from the Sculptor Group
We seek HST ACS/WFC time to conduct a detailed study of the stellar populations of 5 early-type {dE, dE/dIrr} dwarf galaxies in the nearby {~1.5 to 4 Mpc} Sculptor group. Four of these systems have been recently found to contain modest amounts of HI, and existing ground-based and HST snapshot data point to the potential presence of small populations of young {blue} stars in at least three of these systems. Consequently, they resemble the Local Group ‘transition’ objects Phoenix and LGS3. The relative number of such transition systems is thus substantially larger in the low density environment of the Scl group than for the Local Group. Detailed stellar populations studies will allow estimation of the star formation histories, via stellar population modelling of the color-magnitude diagrams, of the target dwarfs, which in turn will connect to gas consumption and retention rates. For the two nearer dwarfs we aim to reach below the horizontal branch {a first for any system beyond the Local Group} equivalent to a main sequence turnoff age of ~1 Gyr. The observations of these two systems will also allow detection of RR Lyrae variables and thus direct confirmation of the presence of old populations. For the other three dwarfs will we cover the first 2.5 mags of the red giant branch, equivalent to the main sequence termination for a ~300 Myr population. The results will have implications for theories of galaxy formation and evolution, particularly with regard to the evolutionary relation between low luminosity dEs and dwarf irregulars.
ACS/WFC 10496
Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters
We propose a novel HST approach to obtain a dramatically more useful “dust free” Type Ia supernovae {SNe Ia} dataset than available with the previous GOODS searches. Moreover, this approach provides a strikingly more efficient search-and-follow-up that is primarily pre- scheduled. The resulting dark energy measurements do not share the major systematic uncertainty at these redshifts, that of the extinction correction with a prior. By targeting massive galaxy clusters at z > 1 we obtain a five-times higher efficiency in detection of Type Ia supernovae in ellipticals, providing a well-understood host galaxy environment. These same deep cluster images then also yield fundamental calibrations required for future weak lensing and Sunyaev-Zel’dovich measurements of dark energy, as well as an entire program of cluster studies. The data will make possible a factor of two improvement on supernova constraints on dark energy time variation, and much larger improvement in systematic uncertainty. They will provide both a cluster dataset and a SN Ia dataset that will be a longstanding scientific resource.
ACS/WFC 10494
Imaging the mass structure of distant lens galaxies
The surface brightness distribution of extended gravitationally lensed arcs and Einstein rings contains super-resolved information about the lensed object, and, more excitingly, about the smooth and clumpy mass distribution of the lens galaxies. The source and lens information can non-parametrically be separated, resulting in a direct “gravitational-mass image” of the inner mass-distribution of cosmologically-distant galaxies {Koopmans 2005}. With this goal in mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W imaging of 15 gravitational-lens systems with spatially resolved lensed sources, selected from the 17 new lens systems discovered by the Sloan Lens ACS Survey {Bolton et al. 2004}. Each system has been selected from the SDSS and confirmed in a time-efficient HST-ACS snapshot program {cycle-13}; they show highly-magnified arcs or Einstein rings, lensed by a massive early-type lens galaxy. High- fidelity multi-color HST images are required {not delivered by the 420-sec snapshot images} to isolate these lensed images {properly cleaned, dithered and extinction-corrected} from the lens galaxy surface brightness distribution, and apply our “gravitational-mass imaging” technique. The sample of galaxy mass distributions – determined through this method from the arcs and Einstein ring HST images – will be studied to: {i} measure the smooth mass distribution of the lens galaxies {Dark and luminous mass are separated using the HST images and the stellar M/L values derived from a joint stellar-dynamical analysis of each system}; {ii} quantify statistically and individually the incidence of mass-substructure {with or without obvious luminous counter- parts such as dwarf galaxies}. Since dark-matter substructure should be considerably more prevalent at higher redshift, both results provide a direct test of this prediction of the CDM hierarchical structure-formation model.
ACS/HRC/WFC 10487
A Search for Debris Disks in the Coeval Beta Pictoris Moving Group
Resolved observations of debris disks present us with the opportunity of studying planetary evolution in other solar systems. We propose to search for debris disks in the Beta Pictoris moving group {8-20 Myrs, 10-50 pc away} , which provides a coeval sample of multiple spectral types, and it has already produced two magnificent resolved debris disks: AU Mic and Beta Pic. Such coeval sample will provide us with a snapshop of the crucial time in disk evolution in which the disk makes the transition from optically thick to optically thin, and it will be useful to study the stellar mass dependence of the disk evolution.
ACS/HRC 10145
Physical parameters of the upper atmosphere of the extrasolar planet HD209458b
Every 3.5 days, the transits of the gaseous planet orbiting HD209458 offer the unique opportunity to investigate the spectral features of an extra-solar planetary atmosphere. Using HST, we first discovered the extended upper atmosphere of HD209458b through the detection of a 15% HI Lyman alpha absorption. We concluded that the hydrogen must be escaping the planet with a lower limit rate of 10^10 g/s {Vidal-Madjar et al. 2003}. Additional observations, subsequently allowed to detect OI and CII in the upper atmosphere implying that this atmosphere is hydrodynamically escaping {in “blow off”, Vidal-Madjar et al. 2004}. Here we propose to further study this upper atmosphere to better constrain the “blow off” state by directly estimating the physical conditions and the flow characteristics. In particular we will determine the temperature and density at the base of the upper atmosphere {the thermosphere}, and the density distribution and ionization state just below that level. Comparison between the optical and ultraviolet occultation light curves will provide useful information on the molecular/haze content of the lower atmosphere. The observation of six HD209458b transits with HRC and SBC settings will allow the detection of many lines adressing these issues. The proposed observations will give us for the first time a detailed probe of the atmosphere of an “evaporating” extra-solar planet.With species as abundant as FeII or MgII, the damping wings in the strongest lines will start to form at levels around 1.9% absorption. Due to either the strength of the MgII doublet lines around 280 nm or the packing of FeII lines, strong absorptions arising from the accumulated damping wings should show up clearly in FeII and MgII. All these signatures should be easily detected even with the 40 to 100 Angstrom resolution of the PR200L prism in these spectral regions. In addition to these goals, any signature of molecules {e.g CO below 154 nm}, dust or haze should also show up as broad band absorption in both PR110L and PR200L settings. The estimate of the planet radius at different wavelengths in the UV would become possible for all efficient absorbers in this spectral range. The achievement of 0.1% precision in the occultation curves thus provides sensitivity high enough to potentially lead to important discoveries.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
10260 – REacq(2,1,1) failed due to search radius limit exceeded. @ 132/1322z During LOS REacq(2,1,1) scheduled at 132/13:22:01 failed due to search radius limit exceeded on FGS-2. ESB “a05” FGS Coarse Track failed – Search Radius Limit exceeded was received. The map at 13:29:29 showed errors of V1=-0.45, V2=-4.69, V3=59.93, RSS=60.12.
10262 – GSAcq(2,1,2) failed to RGA Control @ 132/1935z The GSAcq(2,1,2) scheduled at 132/19:35:38 – 19:44:03 failed to RGA control due to stop flag (QF2STOPF) on FGS-2. Pre-acquisition OBAD’s were successful with (RSS) error corrections of 1982.29 and 2.38 arcseconds.
10263 – ACS Target Acquisition Failed due to GSAcq failure @ 132/1950z The GSAcq prior to the ACS observation (GJ871.1B) failed and as a result the TDF was not in the correct state to allow ACS to proceed with its scheduled (132/19:49:29) Target Acquisition, resulting in the ACS 954 STB message and EXEC 20s received when the SMS scheduled GENSLEW at 132/19:51:26 request was rejected. The following STB messages were received:
At 132/19:50:04 ACS 954, P=1 T=16945
At 132/19:51:28 EXEC 20, P=4000 T=17620
At 132/19:51:29 EXEC 20, P=100000 T=17624
COMPLETED OPS REQUEST:
17758-0 – Genslew for proposal 10487 – slot 2 @ 132/1558z
17759-0 – Genslew for proposal 10487 – slot 3 @ 132/1600z
17753-2 – FSW TDRSS-W Elements Update @ 135/0300z
COMPLETED OPS NOTES:
1474-1 – Adjust ACS Error Count @ 132/2238z
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 28 27 (HSTAR 10262)
FGS REacq 20 19 (HSTAR 10260)
OBAD with Maneuver 90 90
SIGNIFICANT EVENTS: (None)
