Cycle 23 Abstract Catalog (Based on Phase I Submissions) 14066 Proposal Category: GO Scientific Category: Unresolved Stellar Populations and Galaxy ID: 14066 Program Title: Hi-PEEC, Hubble imaging Probe of Extreme Environments and Clusters Principal Investigator: Angela Adamo PI Institution: Stockholm University Starburst events play a major role in shaping the stellar content of galaxies at high redshift, due to the strongly enhanced gas fractions and merger rates in comparison to present-day galaxies. The fossils of those starburst episodes, the globular clusters (GCs), are outstanding witnesses to the dramatic changes that occurred in their host galaxies. To understand and interpret the rapid evolution occurring in starbursts at any redshift, we need to probe how the intensified duty cycle of gas consumption changes the nature of young massive cluster (YMC) populations. We therefore propose Hi-PEEC, an UV-optical study of YMCs in a uniquely accessible sample of 6 starbursts located in the nearby (D<80 Mpc) universe. Our targets have star formation rates higher than or comparable to the Antennae, and rich cluster populations. Monte Carlo simulations, including realistic assumptions of recent burst events and extinction gradients, prove our abilities to recover YMC properties (age, masses, extinction) inside the requested detection limits. We will be able to study the efficiency by which clusters form, the formation modes of the most massive clusters, their age and spatial distributions in mergers, as well as obtain insights into the recent star formation histories of the host galaxies. This proposal is aimed at unveiling the role of starburst environments in shaping the process of star and cluster formation. These studies will have important implications for our understanding of GC formation and will constitute a reference sample for future infrared-limited studies of the highly star-forming and heavily extinguished counterpart galaxies with the JWST. 1 6/30/2015 Cycle 23 Abstract Catalog (Based on Phase I Submissions) 14067 Proposal Category: GO Scientific Category: Unresolved Stellar Populations and Galaxy ID: 14067 Program Title: Searching for a Supermassive Black Hole in the Brightest Ultracompact Dwarf Galaxy Principal Investigator: Chris Ahn PI Institution: University of Utah We request a single orbit of HST time to image the most luminous ultracompact dwarf galaxy (UCD), M59-UCD3, suspected to be the tidally stripped nucleus of a massive galaxy. We will combine these data with adaptive optics kinematic data from Gemini/NIFS to test for the presence of a supermassive black hole (SMBH) in this object. HST imaging will resolve the inner surface brightness profile of this very compact object, which is necessary creating dynamical models and in determining the PSF of the kinematic observations. Due to M59-UCD3's brightness, we expect to be able to detect the signature of any black hole above a few million solar masses; significantly smaller than the 21 million solar mass black hole recently found by our team in the slightly less luminous UCD, M60-UCD1. There is indirect evidence that supermassive black holes in UCDs, like the one in M60-UCD1, may represent a significant new population of supermassive black holes. M59-UCD3 provides an important test of this hypothesis. 2 6/30/2015 Cycle 23 Abstract Catalog (Based on Phase I Submissions) 14068 Proposal Category: GO Scientific Category: AGN/Quasars ID: 14068 Program Title: Resolving the Nuclear Regions of Confirmed Offset AGN Principal Investigator: Robert Barrows PI Institution: University of Colorado at Boulder We propose HST observations of 10 SDSS galaxies that host X-ray detected active galactic nuclei (AGN) that are significantly spatially offset from the SDSS galaxy nucleus. Since the off-nuclear nature of an AGN can only result from a galaxy merger, these systems are confirmed mergers hosting AGN and give us the unique opportunity to study the connection between galaxy mergers and supermassive black hole (SMBH) growth. However, the resolution of the SDSS is insufficient to resolve the nuclear regions of these mergers, and the combined resolution, sensitivity and multi-band capabilities of HST are now necessary to utilize this sample for studies of galaxy and SMBH co-evolution. By also developing a carefully defined control sample from archival data, our proposed multi-band HST/WFC3 observations will permit us to measure the star-formation rates in the nuclear regions, facilitating a comparison between the triggering of AGN and star-formation in galaxy mergers and an investigation into the role mergers play in the co-evolution of galaxies and SMBHs. By resolving the stellar cores associated with the merging galaxies, we can determine the preference of major versus minor mergers in the triggering of AGN. This study can only be accomplished with HST because 1) the resolution of HST is necessary to resolve the nuclear regions of these merging systems; 2) the sensitivity of HST is necessary to detect the stellar cores if the merger is of a minor classification; and 3) the multi-band imaging is necessary to estimate star-formation rates. 3 6/30/2015 Cycle 23 Abstract Catalog (Based on Phase I Submissions) 14069 Proposal Category: GO Scientific Category: Resolved Stellar Populations ID: 14069 Program Title: Searching For Multiple Populations in Massive Young and Intermediate Age Clusters Principal Investigator: Nate Bastian PI Institution: Liverpool John Moores Univeristy We propose to obtain imaging of 12 massive clusters within the LMC/SMC, spanning a wide range of ages (100 Myr - 10 Gyr), in order to search for abundance spreads (i.e. multiple populations) within them. While all ancient globular clusters (GCs) studied to date, in the necessary detail, possess multiple populations, no massive (>10^5 Msun) young (< 1 Gyr) or intermediate (1-8 Gyr) age clusters have been found with abundance spreads. This raises the fundamental question: what controls whether a cluster will host multiple populations? The standard suggestion is that cluster mass is the crucial parameter, although recent results on the initial masses of GCs have called this into question. An alternative view is that GC formation was fundamentally different than the formation of other (< 10 Gyr) massive clusters. The proposed observations will definitively address whether age or mass is the crucial parameter controlling the appearance of multiple populations. The proposed sample occupies a critical region of parameter space (age/mass) where there are no Milky Way counterparts. 4 6/30/2015 Cycle 23 Abstract Catalog (Based on Phase I Submissions) 14070 Proposal Category: GO Scientific Category: Cool Stars ID: 14070 Program Title: A Red Supergiant Mass Accurate to 1% Principal Investigator: Philip Bennett PI Institution: Eureka Scientific Inc. Red supergiants (RSGs) are massive, evolved stars that are among the brightest stars in the near infrared, and often serve as useful ``standard candles'' for extragalactic and cosmological studies. But this use of RSGs is hampered by the lack of fundamental mass and luminosity calibrations tying these objects to the theoretical H-R diagram. Theoretical evolutionary models are not very useful because of mass loss due to stellar winds in the RSG stage. Mass loss in RSG stars is not well understood, and is incorporated using various parameterizations. No accurate observationally-determined RSG masses are available. More than anywhere else in the H-R diagram, there is a pressing need for accurate stellar masses of red supergiants. The determination of an accurate RSG mass is a priority. We propose to determine the mass of the K supergiant in the bright, well-studied, eclipsing binary system 31 Cygni (K4 Ib + B3 V). The orbital solution of the optically-dominant K supergiant has been accurately determined. Given this, a complete solution for both stellar masses can be found from a small number of radial velocity observations of the companion star. For 31 Cyg, archival STIS/E140H observations from 2001-02 (program GO-9109) are well-suited for this purpose. The orbital configuration of 31 Cyg in Cycle 23 is ideally separated by ~0.5 in phase from the archival observations (thereby maximizing the RV difference). We propose to obtain additional STIS/E140H observations in Cycle 23, and use these two sets of FUV observations to determine the mass of the 31 Cyg K supergiant to ~1%. These observations must be done soon, or the optimal phase window for doing so will be lost. 5 6/30/2015 Cycle 23 Abstract Catalog (Based on Phase I Submissions) 14071 Proposal Category: GO Scientific Category: ISM in External Galaxies ID: 14071 Program Title: How are HI Disks Fed? Probing Condensation at the Disk-Halo Interface Principal Investigator: Sanchayeeta Borthakur PI Institution: The Johns Hopkins University Galaxy disks need a continuous supply of cold gas to fuel star formation. While accretion from the intergalactic medium brings in gas, this gas needs to condense down to a temperature <100K to form stars. Here, we propose to investigate the process of accretion and condensation of inflowing warm ionized gas into neutral atomic gas (HI) in the disks of galaxies and how this is affected by feedback from massive stars. To do so, we mount the first controlled absorption- line experiment to probe the interface between the disk and the circumgalactic medium (CGM). This study will complement the parameter space (in terms of impact parameter versus HI disk size) probed by the large HST program COS-GASS (PI:Heckman). Together these two programs will give us a continuous coverage of gas properties in galaxies from disks out to the virial radii. Our sample provides QSO-sightlines through 35 gas-rich galaxies (z= 0.003-0.05) probing them at the disk-CGM interface. The proposed observations will probe a wide range of absorption-line transitions that will help us in identifying the underlying physics behind the process of condensation. We will also use state-of-the art numerical simulations to interpret the observations in a physically motivated context, and provide constraints that test (and then improve) the simulations.
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