NASA Hubble Space Telescope Daily Report #5107
HUBBLE SPACE TELESCOPE DAILY REPORT #5107
Continuing to Collect World Class Science
PERIOD COVERED: 5am May 28 – 5am June 1, 2010 (DOY 148/09:00z-152/09:00z)
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
#12290 GSAcq(1,2,1) failed with Search Radius Limit exceeded on FGS 1 @ 148/15:45
Observations affected: WFC3 #116-117, Proposal #12021.
#12291 GSAcq (2,3,3) resulted in Fine Lock Backup (2,0,2) @ 151/11:22z
Observations possibly affected: ACS #9-10 Proposal #11995; WFC3 #10-11 Proposal #11905; COS #32 Proposal #11894; STIS #3 Proposal #11845; Astrometry Proposals #11704 and #11995.
COMPLETED OPS REQUEST:
#18860-0 Execute ROP NS-12 to Reset STIS FSW Error Counter @ 148/11:26z
#18861-0 Null Genslew for Proposal #12077 – slot 2 @ 148/12:26z
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 32 31
FGS REAcq 29 29
OBAD with Maneuver 24 23
SIGNIFICANT EVENTS: (None)
OBSERVATIONS SCHEDULED:
WFC3/UV 12117
Determining the Nature of an Exceptional Optical Transient
During the course of the Catalina Real-time Transient Survey (CRTS) we have discovered an exceptionally luminous optical transient. The source of this event appears to be either the most luminous supernova ever discovered, or the first clear optical detection of the tidal disruption of a star by a massive black hole. In spite of numerous ground and space-based observations the exact nature of the event remains unclear. High spatial resolution observations with HST WFC3 are critical to solving this mystery.
COS/NUV/S/C/FUV 12082
Extending COS/G130M Coverage Down to 905A With Two New Central Wavelengths.
These exploratory observations will provide sensitivity, wavelength range, and resolution measurements for two new COS FUV G130M central wavelength settings. These new settings will extend COS/G130M coverage down to 905? in two new bandpasses; 1021-1171? (BLUE) and 905-1055? (Ultra-BLUE). The modes are chosen to provide continuous coverage from 905? to the existing coverage in the G130M/1291? setting with approximately 30? of overlap in each mode for cross-calibration purposes. No focus adjustments will be made for these settings, as this is deemed an unnecessary risk to COS.
These new modes have the potential to provide greater than FUSE sensitivity at moderate (3, 000-5, 000) resolution.
Three WD targets are defined;
1) GD50 (GSC-04717-00588; a well observed standard WD) 2) WD0320-539 (GSC-08493-00891, one of the targets used in exploring the G140L sensitivity), 3) REJ0503-289 (WD-5001-289 = GSC-04717-00588, a hot EUVE bright WD)
But only target 2) is used at this time.
In the observations section, G130M/1291A is a placeholder for the BLUE and Super-BLUE settings.
WFC3/UV 12077
Monitoring the Aftermath of an Asteroid Impact Event
Our Director’s Discretionary program (GO-12053) to image the newly discovered object P/2010 A2 executed successfully on 2010 Jan 25 and 29 with spectacular results. Hubble has apparently borne witness to the first detection of a collision in the asteroid belt. Hubble imaging with the WFC3 has revealed an object unlike anything ever seen before and with details impossible to detect with any other facility. We request 6 more orbits of Hubble time (1 orbit every 20 days over the next few months, until the object enters Hubble’s solar exclusion zone in late-June 2010) to monitor the evolution of this remarkable object and further clarify the nature of this event. These observations may usher in a new era of searching for and characterizing collisional events within the asteroid belt.
WFC3/UV/IR 12021
An Irradiated Disk in an Ultraluminous X-Ray Source
Whether ultraluminous X-ray sources (ULXs) contain stellar-mass or intermediate-mass black holes (IMBHs) is an important, but as yet unresolved, astrophysical question. We have discovered variable optical emission from the ULX NGC 5408 X-1 that we interpret as reprocessed emission in an irradiated disk. We propose simultaneous observations with Chandra and HST to test this interpretation and place constraints on the geometry of the accretion disk. The observations should provide a means to discriminate between stellar-mass versus intermediate-mass black holes.
ACS/WFC 11995
CCD Daily Monitor (Part 2)
This program comprises basic tests for measuring the read noise and dark current of the ACS WFC and for tracking the growth of hot pixels. The recorded frames are used to create bias and dark reference images for science data reduction and calibration. This program will be executed four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To facilitate scheduling, this program is split into three proposals. This proposal covers 320 orbits (20 weeks) from 1 February 2010 to 20 June 2010.
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 11915
IR Internal Flat Fields
This program is the same as 11433 (SMOV) and depends on the completion of the IR initial alignment (Program 11425). This version contains three instances of 37 internal orbits: to be scheduled early, middle, and near the end of Cycle 17, in order to use the entire 110-orbit allocation.
In this test, we will study the stability and structure of the IR channel flat field images through all filter elements in the WFC3-IR channel. Flats will be monitored, i.e. to capture any temporal trends in the flat fields and delta flats produced. High signal observations will provide a map of the pixel-to-pixel flat field structure, as well as identify the positions of any dust particles.
WFC3/UVIS 11908
Cycle 17: UVIS Bowtie Monitor
Ground testing revealed an intermittent hysteresis type effect in the UVIS detector (both CCDs) at the level of ~1%, lasting hours to days. Initially found via an unexpected bowtie-shaped feature in flatfield ratios, subsequent lab tests on similar e2v devices have since shown that it is also present as simply an overall offset across the entire CCD, i.e., a QE offset without any discernable pattern. These lab tests have further revealed that overexposing the detector to count levels several times full well fills the traps and effectively neutralizes the bowtie. Each visit in this proposal acquires a set of three 3×3 binned internal flatfields: the first unsaturated image will be used to detect any bowtie, the second, highly exposed image will neutralize the bowtie if it is present, and the final image will allow for verification that the bowtie is gone.
WFC3/UVIS 11907
UVIS Cycle 17 Contamination Monitor
The UV throughput of WFC3 during Cycle 17 is monitored via weekly standard star observations in a subset of key filters covering 200-600nm and F606W, F814W as controls on the red end. The data will provide a measure of throughput levels as a function of time and wavelength, allowing for detection of the presence of possible contaminants.
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).
COS/NUV 11896
NUV Spectroscopic Sensitivity Monitoring
The purpose of this proposal is to monitor sensitivity of each NUV grating mode to detect any changes due to contamination or other causes.
COS/FUV 11895
FUV Detector Dark Monitor
Monitor the FUV detector dark rate by taking long science exposures without illuminating the detector. The detector dark rate and spatial distribution of counts will be compared to pre-launch and SMOV data in order to verify the nominal operation of the detector. Variations of count rate as a function of orbital position will be analyzed to find dependence of dark rate on proximity to the SAA. Dependence of dark rate as function of time will also be tracked.
COS/NUV 11894
NUV Detector Dark Monitor
The purpose of this proposal is to measure the NUV detector dark rate by taking long science exposures with no light on the detector. The detector dark rate and spatial distribution of counts will be compared to pre-launch and SMOV data in order to verify the nominal operation of the detector. Variations of count rate as a function of orbital position will be analyzed to find dependence of dark rate on proximity to the SAA. Dependence of dark rate as function of time will also be tracked.
ACS/WFC3/STIS/CCD 11889
Photometric Cross-Calibration using Stellar Flux Standards
The purpose of this proposal is to: A) Verify the ACS HRC and WFC photometric calibrations with a repeat visit to one of the three primary WDs. B) Measure the change in sensitivity with time for bright stars (which would include any small CTE contributions). C) Continue to investigate the ~2% discrepancy between ACS flux calibration and that of STIS (ACS ISR 2007-06). The goal is to measure any filter bandpass shifts in ACS or rule out the possibility of shifts as the primary contributors to the ACS/STIS discrepancy for cool stars.
STIS/CCD 11852
STIS CCD Spectroscopic Flats C17
The purpose of this proposal is to obtain pixel-to-pixel lamp flat fields for the STIS CCD in spectroscopic mode.
STIS/CC 11847
CCD Bias Monitor-Part 2
Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and 1×1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns.
STIS/CC 11845
CCD Dark Monitor Part 2
Monitor the darks for the STIS CCD.
FGS 11788
The Architecture of Exoplanetary Systems
Are all planetary systems coplanar? Concordance cosmogony makes that prediction. It is, however, a prediction of extrasolar planetary system architecture as yet untested by direct observation for main sequence stars other than the Sun. To provide such a test, we propose to carry out FGS astrometric studies on four stars hosting seven companions. Our understanding of the planet formation process will grow as we match not only system architecture, but formed planet mass and true distance from the primary with host star characteristics for a wide variety of host stars and exoplanet masses.
We propose that a series of FGS astrometric observations with demonstrated 1 millisecond of arc per-observation precision can establish the degree of coplanarity and component true masses for four extrasolar systems: HD 202206 (brown dwarf+planet); HD 128311 (planet+planet), HD 160691 = mu Arae (planet+planet), and HD 222404AB = gamma Cephei (planet+star). In each case the companion is identified as such by assuming that the minimum mass is the actual mass. For the last target, a known stellar binary system, the companion orbit is stable only if coplanar with the AB binary orbit.
COS/NUV/FUV 11741
Probing Warm-Hot Intergalactic Gas at 0.5 < z < 1.3 with a Blind Survey for O VI, Ne VIII, Mg X, and Si XII Absorption Systems Currently we can only account for half of the baryons (or less) expected to be found in the nearby universe based on D/H and CMB observations. This “missing baryons problem” is one of the highest-priority challenges in observational extragalatic astronomy. Cosmological simulations suggest that the baryons are hidden in low-density, shock-heated intergalactic gas in the log T = 5 – 7 range, but intensive UV and X-ray surveys using O VI, O VII, and O VIII absorption lines have not yet confirmed this prediction. We propose to use COS to carry out a sensitive survey for Ne VIII and Mg X absorption in the spectra of nine QSOs at z(QSO) > 0.89. For the three highest-redshift QSOs, we will also search for Si XII. This survey will provide more robust constraints on the quantity of baryons in warm-hot intergalactic gas at 0.5 < z < 1.3, and the data will provide rich constraints on the metal enrichment, physical conditions, and nature of a wide variety of QSO absorbers in addition to the warm-hot systems. By comparing the results to other surveys at lower redshifts (with STIS, FUSE, and from the COS GTO programs), the project will also enable the first study of how these absorbers evolve with redshift at z < 1. By combining the program with follow-up galaxy redshift surveys, we will also push the study of galaxy-absorber relationships to higher redshifts, with an emphasis on the distribution of the WHIM with respect to the large-scale matter distribution of the universe. ACS/WFC3 11735 The LSD Project: Dynamics, Merging and Stellar Populations of a Sample of Well-Studied LBGs at z~3 A large observational effort with the ground-based ESO/VLT telescopes allowed us to obtain deep, spatially-resolved, near-IR spectra of complete sample of 11 Lyman-Break Galaxies at z~3.1. These observations were used to obtain, for the first time, the metallicity and the dynamical properties of a sample of objects that, albeit small, is representative of the total population of the LBGs. We propose to use HST to obtain high-resolution optical and near-IR images of this sample of LBGs in order to study the broad-band morphology and the stellar light distribution of these galaxies. These images, exploiting the superior spatial resolution of HST images and the low-background : 1- will allow a precise measure of the dynamical mass from the velocity field derived with spectroscopy; 2- will permit a comparison of the distribution of star formation (from the line emission) with the underlying stellar population, and, 3- will be used to check if the complex velocity field and the multiple line-emitting regions detected in most targets can be ascribed to on-going mergers. This accurate study will shed light on a number of unsolved problems still affecting the knowledge of the LBGs. COS/NUV/FUV 11728 The Impact of Starbursts on the Gaseous Halos of Galaxies Perhaps the most important (yet uncertain) aspects of galaxy evolution are the processes by which galaxies accrete gas and by which the resulting star formation and black hole growth affects this accreting gas. It is believed that both the form of the accretion and the nature of the feedback change as a function of the galaxy mass. At low mass the gas comes in cold and the feedback is provided by massive stars. At high mass, the gas comes in hot, and the feedback is from an AGN. The changeover occurs near the mass where the galaxy population transitions from star-forming galaxies to red and dead ones. The population of red and dead galaxies is building with cosmic time, and it is believed that feedback plays an important role in this process: shutting down star formation by heating and/or expelling the reservoir of cold halo gas. To investigate these ideas, we propose to use COS far-UV spectra of background QSOs to measure the properties of the halo gas in a sample of galaxies near the transition mass that have undergone starbursts within the past 100 Myr to 1 Gyr. The galactic wind associated with the starburst is predicted to have affected the properties of the gaseous halo. To test this, we will compare the properties of the halos of the post-starburst galaxies to those of a control sample of galaxies matched in mass and QSO impact parameter. Do the halos of the post-starburst galaxies show a higher incidence rate of Ly-Alpha and metal absorption-lines? Are the kinematics of the halo gas more disturbed in the post-starbursts? Has the wind affected the ionization state and/or the metallicity of the halo? These data will provide fresh new insights into the role of feedback from massive stars on the evolution of galaxies, and may also offer clues about the properties of the QSO metal absorption-line systems at high-redshift . STIS/CCD 11721 Verifying the Utility of Type Ia Supernovae as Cosmological Probes: Evolution and Dispersion in the Ultraviolet Spectra The study of distant type Ia supernova (SNe Ia) offers the most practical and immediate discriminator between popular models of dark energy. Yet fundamental questions remain over possible redshift-dependent trends in their observed and intrinsic properties. High-quality Keck spectroscopy of a representative sample of 36 intermediate redshift SNe Ia has revealed a surprising, and unexplained, diversity in their rest-frame UV fluxes. One possible explanation is hitherto undiscovered variations in the progenitor metallicity. Unfortunately, this result cannot be compared to local UV data as only two representative SNe Ia have been studied near maximum light. Taking advantage of two new `rolling searches’ and the restoration of STIS, we propose a non-disruptive TOO campaign to create an equivalent comparison local sample. This will allow us to address possible evolution in the mean UV spectrum and its diversity, an essential precursor to the study of SNe beyond z~1. WFC3/IR 11712 Calibration of Surface Brightness Fluctuations for WFC3/IR We aim to characterize galaxy surface brightness fluctuations (SBF), and calibrate the SBF distance method, in the F110W and F160W filters of the Wide Field Camera 3 IR channel. Because of the very high throughput of F110W and the good match of F160W to the standard H band, we anticipate that both of these filters will be popular choices for galaxy observations with WFC3/IR. The SBF signal is typically an order of magnitude brighter in the near-IR than in the optical, and the characteristics (sensitivity, FOV, cosmetics) of the WFC3/IR channel will be enormously more efficient for SBF measurements than previously available near-IR cameras. As a result, our proposed SBF calibration will allow accurate distance derivation whenever an early-type or bulge-dominated galaxy is observed out to a distance of 150 Mpc or more (i.e., out to the Hubble flow) in the calibrated passbands. For individual galaxy observations, an accurate distance is useful for establishing absolute luminosities, black hole masses, linear sizes, etc. Eventually, once a large number of galaxies have been observed across the sky with WFC3/IR, this SBF calibration will enable accurate mapping of the total mass density distribution in the local universe using the data available in the HST archive. The proposed observations will have additional important scientific value; in particular, we highlight their usefulness for understanding the nature of multimodal globular cluster color distributions in giant elliptical galaxies. WFC3/UV/ACS/WFC 11710 The Extreme Globular Cluster System of Abell 1689: The Ultimate Test of Universal Formation Efficiency The stellar masses of the most luminous galaxies poorly represent the masses of the halos in which they reside. However, recent studies of the very rich globular cluster (GC) populations in the centers of galaxy clusters point toward an apparently linear scaling of the number of GCs with the total core mass of the galaxy cluster. Thus, unlike for the stars in cD galaxies, GC formation in these systems appears to have proceeded with a roughly universal mass conversion efficiency. GCs are also distinct in that their spatial distributions are more extended than the starlight, and recent simulations suggest that they follow the mass density profile of the merged dark matter halos that formed stars at high redshift. To provide a definitive test of the universal efficiency hypothesis requires measuring the number of GCs in the most massive galaxy clusters, where the number should be a factor of 5 or more greater than seen in M87. Likewise, the relationship between GCs and mass density can only be tested in systems where the total mass and mass density are well-determined. Fortunately, the imaging power of HST brings the GC population of Abell 1689, the most extreme high-mass lensing cluster, into range. Estimates of the size of the A1689 GC population from available data suggest an unprecedented 100, 000 GCs, but this number is based on the tip of the iceberg and is extremely uncertain. We propose to obtain the first accurate measurement of the number of GCs and their density profile in this extraordinary system – the most massive and most distant GC system ever studied – and thus make the ultimate test of the universal GC formation hypothesis. Our deep I-band image will also provide a stringent “null-detection” test of several known z>7 galaxy candidates and improve the mass model of the system by increasing the number of usable lensed background galaxies. Finally, we will take deep multi-band parallel observations with WFC3/IR to help in quantifying the abundance of rare faint red objects.
FGS 11704
The Ages of Globular Clusters and the Population II Distance Scale
Globular clusters are the oldest objects in the universe whose age can be accurately determined. The dominant error in globular cluster age determinations is the uncertain Population II distance scale. We propose to use FGS 1R to obtain parallaxes with an accuracy of 0.2 milliarcsecond for 9 main sequence stars with [Fe/H] < -1.5. This will determine the absolute magnitude of these stars with accuracies of 0.04 to 0.06mag. This data will be used to determine the distance to 24 metal-poor globular clusters using main sequence fitting. These distances (with errors of 0.05 mag) will be used to determine the ages of globular clusters using the luminosity of the subgiant branch as an age indicator. This will yield absolute ages with an accuracy of 5%, about a factor of two improvement over current estimates. Coupled with existing parallaxes for more metal-rich stars, we will be able to accurately determine the age for globular clusters over a wide range of metallicities in order to study the early formation history of the Milky Way and provide an independent estimate of the age of the universe. The Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an absolute magnitude error less than 0.18 mag which is suitable for use in main sequence fitting. Previous attempts at main sequence fitting to metal-poor globular clusters have had to rely on theoretical calibrations of the color of the main sequence. Our HST parallax program will remove this source of possible systematic error and yield distances to metal-poor globular clusters which are significantly more accurate than possible with the current parallax data. The HST parallax data will have errors which are 10 times smaller than the current parallax data. Using the HST parallaxes, we will obtain main sequence fitting distances to 11 globular clusters which contain over 500 RR Lyrae stars. This will allow us to calibrate the absolute magnitude of RR Lyrae stars, a commonly used Population II distance indicator. WFC3/UVIS/IR 11700 Bright Galaxies at z>7.5 with a WFC3 Pure Parallel Survey
The epoch of reionization represents a special moment in the history of the Universe as it is during this era that the first galaxies and star clusters are formed. Reionization also profoundly affects the environment where subsequent generations of galaxies evolve. Our overarching goal is to test the hypothesis that galaxies are responsible for reionizing neutral hydrogen. To do so we propose to carry out a pure parallel WFC3 survey to constrain the bright end of the redshift z>7.5 galaxy luminosity function on a total area of 176 arcmin^2 of sky. Extrapolating the evolution of the luminosity function from z~6, we expect to detect about 20 Lyman Break Galaxies brighter than M_* at z~8 significantly improving the current sample of only a few galaxies known at these redshifts. Finding significantly fewer objects than predicted on the basis of extrapolation from z=6 would set strong limits to the brightness of M_*, highlighting a fast evolution of the luminosity function with the possible implication that galaxies alone cannot reionize the Universe. Our observations will find the best candidates for spectroscopic confirmation, that is bright z>7.5 objects, which would be missed by small area deeper surveys. The random pointing nature of the program is ideal to beat cosmic variance, especially severe for luminous massive galaxies, which are strongly clustered. In fact our survey geometry of 38 independent fields will constrain the luminosity function like a contiguous single field survey with two times more area at the same depth. Lyman Break Galaxies at z>7.5 down to m_AB=26.85 (5 sigma) in F125W will be selected as F098M dropouts, using three to five orbits visits that include a total of four filters (F606W, F098M, F125W, F160W) optimized to remove low-redshift interlopers and cool stars. Our data will be highly complementary to a deep field search for high- z galaxies aimed at probing the faint end of the luminosity function, allowing us to disentangle the degeneracy between faint end slope and M_* in a Schechter function fit of the luminosity function. We waive proprietary rights for the data. In addition, we commit to release the coordinates and properties of our z>7.5 candidates within one month from the acquisition of each field.
COS/NUV/FUV 11698
The Structure and Dynamics of Virgo’s Multi-Phase Intracluster Medium
The dynamical flows of the intracluster medium (ICM) are largely unknown. We propose to map the spatial and kinematic distribution of the warm ICM of the nearby Virgo cluster using the Cosmic Origins Spectrograph. 15 sightlines at a range of impact parameters within the virial radius of the cluster (0.2 – 1.7 Mpc) will be probed for Lyman-alpha absorption and the data compared to blind HI, dust and x-ray surveys to create a multi-phase map of the cluster’s ICM. Absorption line sightlines are commonly 40-100 kpc from a galaxy, allowing the flow of baryons between galaxies and the ICM to be assessed. The velocity distribution of the absorbers will be directly compared to simulations and used to constrain the turbulent motions of the ICM. This proposal will result in the first map of a cluster’s warm ICM and provide important tests for our theoretical understanding of cluster formation and the treatment of gas cooling in cosmological simulations.
WFC3/IR 11696
Infrared Survey of Star Formation Across Cosmic Time
We propose to use the unique power of WFC3 slitless spectroscopy to measure the evolution of cosmic star formation from the end of the reionization epoch at z>6 to the close of the galaxy- building era at z~0.3.Pure parallel observations with the grisms have proven to be efficient for identifying line emission from galaxies across a broad range of redshifts. The G102 grism on WFC3 was designed to extend this capability to search for Ly-alpha emission from the first galaxies. Using up to 250 orbits of pure parallel WFC3 spectroscopy, we will observe about 40 deep (4-5 orbit) fields with the combination of G102 and G141, and about 20 shallow (2-3 orbit) fields with G141 alone.
Our primary science goals at the highest redshifts are: (1) Detect Lya in ~100 galaxies with z>5.6 and measure the evolution of the Lya luminosity function, independent of of cosmic variance; 2) Determine the connection between emission line selected and continuum-break selected galaxies at these high redshifts, and 3) Search for the proposed signature of neutral hydrogen absorption at re-ionization. At intermediate redshifts we will (4) Detect more than 1000 galaxies in Halpha at 0.5
We propose to directly image the star-forming regions of z>2 damped Lya systems (DLAs) using the WFC3/UVIS camera on the Hubble Space Telescope. In contrast to all previous attempts to detect the galaxies giving rise to high redshift DLAs, we will use a novel technique that completely removes the glare of the background quasar. Specifically, we will target quasar sightlines with multiple DLAs and use the higher redshift DLA as a “blocking filter” (via Lyman limit absorption) to eliminate all FUV emission from the quasar. This will allow us to carry out a deep search for FUV emission from the lower redshift DLA, shortward of the Lyman limit of the higher redshift absorber. The unique filter set and high spatial resolution afforded by WFC3/UVIS will then enable us to directly image the lower redshift DLA and thus estimate its size, star- formation rate and impact parameter from the QSO sightline. We propose to observe a sample of 20 sightlines, selected primarily from the SDSS database, requiring a total of 40 HST orbits. The observations will allow us to determine the first FUV luminosity function of high redshift DLA galaxies and to correlate the DLA galaxy properties with the ISM characteristics inferred from standard absorption-line analysis to significantly improve our understanding of the general DLA population.
WFC3/ACS/UVIS/IR 11570
Narrowing in on the Hubble Constant and Dark Energy
A measurement of the Hubble constant to a precision of a few percent would be a powerful aid to the investigation of the nature of dark energy and a potent “end-to end” test of the present cosmological model. In Cycle 15 we constructed a new streamlined distance ladder utilizing high- quality type Ia supernova data and observations of Cepheids with HST in the near-IR to minimize the dominant sources of systematic uncertainty in past measurements of the Hubble constant and reduce its total uncertainty to a little under 5%. Here we propose to exploit this new route to reduce the remaining uncertainty by more than 30%, translating into an equal reduction in the uncertainty of the equation of state of dark energy. We propose three sets of observations to reach this goal: a mosaic of NGC 4258 with WFC3 in F160W to triple its sample of long period Cepheids, WFC3/F160W observations of the 6 ideal SN Ia hosts to triple their samples of Cepheids, and observations of NGC 5584 the host of a new SN Ia, SN 2007af, to discover and measure its Cepheids and begin expanding the small set of SN Ia luminosity calibrations. These observations would provide the bulk of a coordinated program aimed at making the measurement of the Hubble constant one of the leading constraints on dark energy.
WFC3/UVI/IR 11557
The Nature of Low-Ionization BAL QSOs
The rare subclass of optically-selected QSOs known as low-ionization broad absorption line (LoBAL) QSOs show signs of high-velocity gas outflows and reddened continua indicative of dust obscuration. Recent studies show that galaxies hosting LoBAL QSOs tend to be ultraluminous infrared systems that are undergoing mergers, and that have dominant young (< 100 Myr) stellar populations. Such studies support the idea that LoBAL QSOs represent a short- lived phase early in the life of QSOs, when powerful AGN-driven winds are blowing away the dust and gas surrounding the QSO. If so, understanding LoBALs would be critical in the study of phenomena regulating black hole and galaxy evolution, such as AGN feedback and the early stages of nuclear accretion. These results, however, come from very small samples that may have serious selection biases. We are therefore taking a more aggressive approach by conducting a systematic multiwavelength study of a volume limited sample of LoBAL QSOs at 0.5 < z < 0.6 drawn from SDSS. We propose to image their host galaxies in two bands using WFC3/UVIS and WFC3/IR to study the morphologies for signs of recent tidal interactions and to map their interaction and star forming histories. We will thus determine whether LoBAL QSOs are truly exclusively found in young merging systems that are likely to be in the early stages of nuclear accretion.
WFC3/UV 11556
Investigations of the Pluto System
We propose a set of high SNR observations of the Pluto system that will provide improved lightcurves, orbits, and photometric properties of Nix and Hydra. The key photometric result for Nix and Hydra will be a vastly improved lightcurve shape and rotation period to test if the objects are in synchronous rotation or not. A second goal of this program will be to retrieve a new epoch of albedo map for the surface of Pluto. These observations will also improve masses and in some case densities for the bodies in the Pluto system.
NIC2/WFC3/IR 11219
Active Galactic Nuclei in Nearby Galaxies: A New View of the Origin of the Radio-Loud Radio- Quiet Dichotomy?
Using archival HST and Chandra observations of 34 nearby early-type galaxies (drawn from a complete radio selected sample) we have found evidence that the radio-loud/radio-quiet dichotomy is directly connected to the structure of the inner regions of their host galaxies in the following sense: [1] Radio-loud AGN are associated with galaxies with shallow cores in their light profiles [2] Radio-quiet AGN are only hosted by galaxies with steep cusps. Since the brightness profile is determined by the galaxy’s evolution, through its merger history, our results suggest that the same process sets the AGN flavor. This provides us with a novel tool to explore the co-evolution of galaxies and supermassive black holes, and it opens a new path to understand the origin of the radio-loud/radio-quiet AGN dichotomy. Currently our analysis is statistically incomplete as the brightness profile is not available for 82 of the 116 targets. Most galaxies were not observed with HST, while in some cases the study is obstructed by the presence of dust features. We here propose to perform an infrared NICMOS snapshot survey of these 82 galaxies. This will enable us to i) test the reality of the dichotomic behavior in a substantially larger sample; ii) extend the comparison between radio-loud and radio-quiet AGN to a larger range of luminosities.
WFC3/ACS/IR 11142
Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3
