Cycle 20 Abstract Catalog (Based on Phase I Submissions) Proposal Category: AR Scientific Category: STAR FORMATION ID: 12814 Program Title: Signatures of turbulence in directly imaged protoplanetary disks Principal Investigator: Philip Armitage PI Institution: University of Colorado at Boulder HST imaging of the edge-on protoplanetary disk in the HH 30 system has shown that substantial changes to the morphology of the disk occur on time scales much shorter than the local dynamical time. This may be due to time- variable obscuration of starlight by the turbulent inner disk. More recently, mid-infrared variability of protoplanetary disks has been attributed to a similar physical origin. We propose a theoretical investigation that will establish whether the optical and infrared variability is due to turbulent variations in the scale height of dust in the inner disk, and determine what observations of that variability can tell us of the nature of disk turbulence. We will use a new generation of global magnetohydrodynamic simulations to directly model the turbulence in an annulus of the inner disk, extending from the dust destruction radius out to the radius where turbulence is quenched by poor coupling of the gas to magnetic fields. We will use the output of the MHD simulations as input to Monte Carlo radiative transfer calculations of stellar irradiation of the outer disk. We will use these calculations to produce light curves that show how time variable shadowing from the inner disk affects the outer disk observables: scattered light images and the infrared spectral energy distribution. Proposal Category: GO Scientific Category: COOL STARS ID: 12815 Program Title: Photometry of the Coldest Benchmark Brown Dwarf Principal Investigator: Kevin Luhman PI Institution: The Pennsylvania State University In 2011, we used images from the Spitzer Space Telescope to discover the coldest directly imaged companion to a nearby star (300-345 K). In addition to breaking new ground in terms of temperature, this companion is one of a small number of benchmark brown dwarfs whose ages and distances are known via their primaries and thus can provide unusually stringent tests of theoretical models of substellar objects. However, few data are available for this companion for comparison to the models; we have measured photometry from two Spitzer bands, but it has not been detected at near-IR wavelengths with the largest ground-based telescopes (J>23.9). Therefore, we propose to use WFC3 to obtain deeper near-IR images of this object so that we can better test model atmospheres in a previously unexplored regime of temperature. 1 2/12/2013 Cycle 20 Abstract Catalog (Based on Phase I Submissions) Proposal Category: GO Scientific Category: QUASAR ABSORPTION LINES AND IGM ID: 12816 Program Title: Probing the Reionization Epoch of IGM Helium: A Detailed Follow-up Study of Three High-Quality He II Quasars Principal Investigator: David Syphers PI Institution: University of Colorado at Boulder The full reionization of intergalactic helium likely occurred at redshifts between z=2.7 and 4, dramatically affecting the state of the IGM, including strong heating of the gas. Detailed UV spectral studies of He II Ly-alpha absorption toward a handful of quasars at 2.7<z<3.3 confirm the potential of such IGM probes, but the very small sample (3 sightlines) with detailed, high-S/N information limits the confidence in cosmological inferences. In recent cycles we have been very successful in identifying many new He II quasars at a wide range of redshifts. Here we follow up on the best of these, three uniquely bright He II quasars, including one at higher redshift. SDSSJ0915+4756, at z=3.34, is the brightest confirmed in the FUV at z>2.9, while HS1024+1849 and 4C57.27 are the brightest He II quasars without existing high- resolution and high-S/N observations. We propose a 25-orbit program that will study: (1) the currently ill-constrained evolution of He II reionization, from its end to well before completion; (2) the He II Ly-alpha forest; (3) the interaction of quasars and the IGM with the line-of-sight and transverse proximity effects; (4) high-redshift, high-opacity IGM He II using both Ly-alpha and Ly-beta Gunn-Peterson troughs. Proposal Category: GO Scientific Category: COSMOLOGY ID: 12817 Program Title: Longevity of dark matter substructure in Abell 3827 Principal Investigator: Richard Massey PI Institution: University of Durham We will investigate the interaction properties of dark matter, through the infall of substructure into a galaxy cluster 2 2/12/2013 Cycle 20 Abstract Catalog (Based on Phase I Submissions) with a rare dynamical history. Abell 3827 appears to have grown rapidly through several simultaneous mergers, and currently hosts the stellar remnants of five massive elliptical galaxies within 15 kpc of the core. Only one other well- studied cluster (Abell 2261) contains a distribution of baryonic matter that is even comparably corrugated – and a strong lens threaded through the core of Abell 3827 provides a unique gravitational handle on its distribution of dark matter.! We will measure the late-stage dissipation of the dark matter halos that would have initially accompanied the infalling galaxies. The timescale for this dissipation is a key ingredient in models of structure formation. Most interestingly, our analysis of extant ground-based data also found dark matter offset from its stellar counterpart. This is predicted by numerical simulations if dark matter has (even a small) self-interaction cross section. If confirmed by a robust HST analysis, this result would achieve the same level of impact on fundamental physics as did HST confirmation of the Bullet Cluster offset between dark matter and gas. Constraints on both the tidal gravitational stripping and electroweak interactions of dark matter will be especially aided by the simultaneous measurement of multiple substructures within this single extended halo.! This project will require UV, optical and NIR imaging, plus a combined strong-lensing, weak-lensing and flexion analysis. We request six orbits with WFC3/UVIS, ACS/WFC and WFC3/IR, and will also exploit new Chandra data already in the archive. Proposal Category: AR Scientific Category: AGN/QUASARS ID: 12818 Program Title: The Origin of the Intrinsic Scatter in the Correlation Between Black Hole Mass and Bulge Luminosity in Active Galaxies Principal Investigator: Luis Ho PI Institution: Carnegie Institution of Washington The scaling relation between black hole (BH) mass and bulge luminosity is a fundamental tool to study the interplay between BH growth and galaxy formation. Recent studies suggest that the BH-bulge relation evolves rapidly with redshift. This potentially very important result critically depends on our knowledge of the local scaling relation for actively growing BHs (namely AGNs), which is still poorly known. In two prior archival programs, we have embarked on an extensive effort to characterize the zeropoint, slope, and scatter of the BH mass-bulge luminosity relation for a sample of 235 local (z < 0.35) broad-line AGNs (quasars and Seyfert 1s). This is the largest, most comprehensive sample to date, one that spans the widest range in luminosity, BH mass, and host morphology. This work serves as the definitive reference point for all investigations of the cosmic evolution of the BH-host relations. Our analysis employs a sophisticated new technique to decompose the 2-D structure of the host galaxies with unprecedented accuracy. We find that the scaling relation in the R band shows significant intrinsic scatter that depends systematically on Eddington ratio (accretion rate). AGNs with higher Eddington ratio tend to have either lower BH masses or more luminous bulges. The latter could be caused by enhanced ongoing or recent star formation linked to BH accretion. We propose to test this interesting possibility and to resolve this important ambiguity by studying the color and color gradients of the hosts using all available multi-filter data in the archives. Over 40% (101/235) of our parent sample contains usable WFPC2, ACS, and NICMOS images for this purpose. Proposal Category: AR Scientific Category: COSMOLOGY 3 2/12/2013 Cycle 20 Abstract Catalog (Based on Phase I Submissions) ID: 12819 Program Title: Probing the Formation of Dust in the Early Universe Principal Investigator: Steven Finkelstein PI Institution: University of Texas at Austin We request archival student funding to complete a study on the rest-frame ultraviolet (UV) colors of galaxies at z=8, using new Cycle 19 data in the Hubble Ultra Deep Field (HUDF). The addition of these new data quadruple the exposure time in the F105W band, allowing the compilation of much more robust samples of z=8 galaxies. In addition, this program obtains data in a new filter, F140W, which will allow robust colors of z=8 galaxies to be measured. The only color of z=8 galaxies measurable with the previous data in the HUDF is F125W-F160W, which is contaminated by both the Lyman break, and Lyman alpha emission.! ! Our previous work has examined in detail the evolution of the rest-frame UV colors of galaxies from 4 < z < 7. We found that while typical galaxies at z~7 are dust free, those at z < 6 become progressively dustier. This is consistent with a scenario where the typical high redshift galaxy does not build up its dust reservoir until low-mass AGB stars begin producing dust, which will occur at z < 7 assuming galaxies form at z ~ 15-20. Any dust formed in supernovae is lost in the low-mass galaxies due to outflows, similar to the mass-metallicity relation at lower redshift.! ! Pushing these studies to z~8 will allow us to test this hypothesis. If z~7 galaxies are truly dust free, than z~8 galaxies should have similar colors.