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Hubble Space Telescope
The HubbleObserver Corner for October 2011

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Proposal ID = 12190
Principle Investigator = Dr. Anton M. Koekemoer, Space Telescope Science Institute
Title = "WFC3/IR Spectroscopy of the Highest Redshift Black Hole Candidates"
Time = Oct 28, 2011 19:42:41 - 22:21:45
Target(s) = COSMOS-AGN2
Instrument(s) = WFC3/IR-GRISM

Background:

Black holes are probably the most fascinating astronomical objects for the public. The idea that the gravitational field is so intense that it bends the light that comes from the object right back onto itself, and hence becomes invisible, is fascinating for people. Fortunately, light from the accretion disk around the black hole can still be seen, and in the case of massive black holes at the centers of galaxies, gives rise to what are called Active Galactic Nuclei (AGNs). This program observes a sample of very distant (i.e., very high redshift; z > 7) AGNs in order to learn more about the growth of black holes. In particular, how they became so massive so fast, since galaxies at z > 7 are also very young. The program uses a GRISM (a combination of a diffraction grating and prism) to obtain the spectrum of the AGN in order to both confirm the redshift, and to provide a variety of diagnostics for understanding the properties of the galaxy. This observation is the 14th target from a sample of 16 for this proposal.

Paraphrasing from the abstract:

We propose to obtain WFC3/IR grism spectroscopy of our most robust sample of z>7 active galactic nuclei (AGN), selected from the most extensive X-ray and multi-band surveys to date, drawing from both GOODS and COSMOS. These sources represent our best opportunity to understand the formation and growth of black holes, and their role in galaxy evolution, within the first 800 Myr of cosmic time. A key mystery in our understanding of black hole growth is how they are able to grow so rapidly by z~6.4, which is the highest redshift for any spectroscopically confirmed AGN to date. Extensive ground-based NIR spectroscopic efforts on 8-10m telescopes to extend this redshift frontier to more distant AGN have so far proved fruitless, predominantly limited by the ground-based IR sky and the faintness of these sources. The unique gains afforded by WFC3/IR now provide us with the ability to open up this piece of parameter space, crucial to understanding how these sources form and evolve. We will also search for signatures of star formation that may be occurring in conjunction with the black hole feeding phase.

You can find most of this information and more from the HST Webpage by entering "12190" in the Prop. ID box.


Proposal ID = 12025
Principle Investigator = Dr. James Green, University of Colorado at Boulder
Title = "COS-GTO: QSO Absorbers, Galaxies and Large-scale 
          Structures in the Local Universe Part 2"
Time = Oct 23, 2011 16:24:18	- 22:23:02
Target(s) = 1SAXJ1032.3+5051, ANY
Instrument(s) = COS/FUV, COS/NUV, WFC3/IR, WFC3/UVIS

Background:

This program is part of the Guaranteed Time Observers (GTO) program which is granted to the builders of the Cosmic Origins Spectrograph (COS) team as part of their reward for designing and constructing the instrument. The "ANY" listed as the second target refers to the fact that while the telescope is pointed at the primary target (1SAXJ1032.3+5051) in order to obtain observations with COS, it is also taking data in "parallel" at a field just to the side of this target (i.e., a few arc minutes away) with the Wide Field Camera 3 (WFC3). This is a common configuration which is used to increase the efficiency of Hubble observations. The team is addressing a large number of different science questions as outlined below.

Paraphrasing from the abstract:

This is a program to probe the large scale structure of baryons in the universe. Subcategories to address various questions are:

1. Target 8 bright BL Lac objects to search for low contrast Ly alpha absorbers from the warm-hot interstellar medium (WHIM). Example of science drivers: What are physical conditions and extent of warm-hot IGM in the current epoch?

2. Ly alpha cloud sizes: A bright AGN pair which yield tangential distance separations of 100--500 kpc at z=0.01--0.05. Example of science drivers: What are the characteristic sizes of Ly alpha absorbers, weak metal-line absorbers and absorbers in voids?

3. Probes of starburst outflows: The targets are bright AGN, <= 100 kpc in projection out of the minor axis of nearby starburst galaxies. Example of science drivers: Do starburst winds from massive galaxies escape the galaxy's gravitational potential?

4. A large galaxy's gaseous halo: Three probes of the kinematics and metallicity of a single L* galaxy halo. Example of science drivers: What are the extent, metallicity, ionization conditions and kinematics of gaseous halos of normal luminous (L*) galaxies?

5. Dwarf galaxy winds: Probe the kinematics and metallicities of outflows from active and inactive dwarfs. Example of science drivers: What is the evidence that current star forming dwarfs or "dormant" (LSB) dwarfs create unbound winds sufficient to account for all weak metal-line absorbers at high- and low-z?

6. M31 Galaxy Halo: Probe the large scale structure of baryons in the universe. Example of science drivers include: What are the extent, metallicity, ionization and kinematics of gaseous halos of galaxies?

You can find most of this information and more on the HST Homepage by entering "12025" in the Prop. ID box.


Proposal ID = 12067
Principle Investigator = Dr. Marc Postman, Space Telescope Science Institute
Title = "Through a Lens, Darkly - New Constraints on the 
         Fundamental Components of the Cosmos"
Time = Oct 11, 2011, 20:15:19 - 23:03:47
Target = MACS0744+3927
Instrument = ACS/WFC, WFC3/UVIS

Background:

Three Multiple Cycle Treasury Programs (MCTPs) were defined in Cycle 18 and will be taking data through Cycle 20. This is one of them; nicknamed CLASH (Cluster Lensing And Supernova survey with Hubble). The program has been awarded 524 orbits over a 3 year period, with the data available immediately for public access. Their goals include the following: "1) Map the distribution of dark matter in galaxy clusters using strong and weak gravitational lensing; 2) Detect Type Ia supernovae out to redshift z ~ 2, allowing us to test the constancy of dark energy's repulsive force over time; 3) Detect and characterize some of the most distant galaxies yet discovered at z > 7; 4) Study the internal structure and evolution of the galaxies in and behind these clusters."

Their website can be accessed at: http://www-int.stsci.edu/~postman/CLASH/Home.html

There is a press release available at: http://hubblesite.org/newscenter/archive/releases/2011/25/

Paraphrasing from the abstract:

As the most massive objects in the universe, galaxy clusters represent important signposts in our story of structure evolution, and are the ultimate telescopic lenses, placing gravitationally lensed galaxies from the earliest epochs in comfortable reach for careful study. We take full advantage of the refurbished ACS and WFC3 cameras to deliver deep 14-filter images of 25 carefully chosen clusters. These will enable us to address timely and substantive questions about dark matter, dark energy, and galaxy evolution well beyond z=7. These X-ray clusters are chosen to be free of lensing bias and to span a wide range of redshift and mass. By combining strong and weak lensing, we will obtain the definitive mass profile of relaxed clusters to confront the distinctive prediction of the standard LambdaCDM model. A supernovae search in parallel (with low magnification uncertainties) will extend the Hubble diagram of SN1a to z>1.5, testing the constancy of dark energy with time and probing progenitor evolution.

You can find most of this information and more from the HST Wabpage by entering "12067" in the Prop. ID box.


Proposal ID = 12218
Principle Investigator = Dr. Derck Massa, Space Telescope Science Institute
Title = "Toward Resolving the Mass Loss Discrepancy"
Time = Oct 4, 2011 03:55:58 - 05:07:17
Target = SK-70D115
Instrument = STIS/CCD, STIS/FUV-MAMMA

Background:

The process of star formation is still very poorly understood, and yet is one of the most important components necessary for answering a range of questions from how galaxies are formed and evolve to how planets form in the debris disks around stars. The recent finding that our understanding of mass loss rates for young super-massive O stars might be off by a factor of 10 therefore represents a fundamental challenge for many astronomical fields. This program will examine a variety of different techniques for measuring mass loss in O stars. The spread in the estimated mass loss range determined using the various diagnostics will indicate whether this is largely a difficulty in measuring mass loss rates accurately, or is an important new result that needs to be taken into account by a large number of different projects.

Paraphrasing from the abstract:

Recent observations have raised serious questions about the mass loss rates of O stars, suggesting that they may be up to 10 times smaller than previously believed. Such a severe revision in the mass loss rates would have wide ranging astrophysical consequences, and has been termed the "mass loss discrepancy". We propose new HST observations aimed at addressing this problem. The new data will be combined with FUSE and existing HST spectra, Spitzer photometry, and optical spectra to create a data set of lasting value. Our proposed analysis will highlight how different wind diagnostics in the same star can yield different results, thereby providing clues to the origin of the discrepancies.

You can find most of this information and more from the HST webpage by entering "12218" in the Prop. ID box.


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