Evaluation of the Implementation of WFIRST/AFTA in the Context of New Worlds, New Horizons in Astronomy and Astrophysics (2014) / Chapter Skim
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1 The WFIRST/AFTA Science Program
1 The WFIRST/AFTA Science Program
Pages 10-26
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From page 10... ...
The combination of the Kepler mission with ground-based follow-up has made great strides in determining the frequency of Earth-like planets around nearby stars. In the sections below, the committee places the scientific rationale for Wide-Field Infrared Survey Telescope (WFIRST)
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From page 11... ...
All of this has been accomplished using extremely careful observations obtained with the Wilkinson Microwave Anisotropy Probe, Planck, the Hubble Space Telescope (HST) , the Chandra X-ray Observatory, and the Fermi Gamma-ray Space Telescope, as well as many ground-based telescopes, including the Sloan Digital Sky Survey, the South Pole Telescope, and the Atacama Cosmology Telescope.
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From page 12... ...
Legends indicate different possible regimes: scalar field models that are "freezing towards" or "thawing from" w = −1, and models with w < −1 in which increasing acceleration leads to a future "big rip." SOURCE: WFIRST-AFTA Science Definition Team and WFIRST Project, Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets: Final Report by the Science Definition Team (SDT) and WFIRST Project, May 23, 2013, http:// wfirst.gsfc.nasa.gov/science/sdt_public/WFIRST-AFTA_SDT_Final_Report_ Rev1_130523.pdf, p.
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from z = 0.2 to z = 1.7. The Large Synoptic Survey Telescope (LSST)
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In principle, ground-based 21-cm observations, such as those planned for CHIME, could reach similar precision over this redshift range, although this technique remains to be proven. Growth -- Redshift Space Distortions Density peaks in the matter distribution will be surrounded by infalling mat ter, which drives the growth of large-scale structures.
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From page 15... ...
WFIRST, LSST, and Euclid -- A Powerful Complementary Program for Cosmology in the Next Decade WFIRST/AFTA, as a large-aperture near-infrared (NIR) space mission, will provide a unique combination of sensitivity and wavelength coverage that comple ments Euclid and LSST.
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From page 16... ...
Finding 1-1: WFIRST/AFTA observations will provide a very strong comple ment to the Euclid and LSST data sets. Finding 1-2: For each of the cosmological probes described in NWNH, WFIRST/AFTA exceeds the goals set out in NWNH.
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From page 17... ...
on HST. This capa bility would address some of the astrometry-based exoplanet science envisioned by the NWNH panels and will also help to break microlensing degeneracies, either by measuring the lens-source angular separation well after the microlensing event or by measuring the time-varying centroid shift during the lensing event due to the multiple images produced by the lensing.
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From page 18... ...
SOURCE: Caption and image from WFIRST-AFTA Science Definition Team and WFIRST Project, Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets: Final Report by the Science Definition Team (SDT) and WFIRST Project, May 23, 2013, http://wfirst.
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From page 19... ...
The astrometric capabilities of WFIRST/AFTA would complement those of the ESA Gaia mission and could touch on science ranging from galactic structure to Kuiper Belt objects. Here, the com mittee focuses on one of the three areas that NWNH recommended as a focused science objective, namely, "Cosmic Dawn: Searching for the First Stars, Galaxies, and Black Holes." This area has progressed very rapidly since NWNH, driven largely by deep-NIR surveys of the early universe using the WFC3 on HST, supported by observations with large ground-based telescopes and multi-waveband telescopes in space.
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From page 20... ...
The numbers below each color bar indicate the size of the point spread function in units of 0.01 arcsec. SOURCE: WFIRST-AFTA Science Definition Team and WFIRST Project, Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets: Final Report by the Science Definition Team (SDT)
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Specifically, NWNH recommended the following: NASA and NSF should support an aggressive program of ground-based high-preci sion radial velocity surveys of nearby stars to identify potential candidates. In the first part of the decade NASA should support competed technology development to advance multiple possible technologies for a next-decade planet imager, and should accelerate measurements of exozodiacal light levels that will determine the size and complexity of such missions.
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From page 22... ...
Detection of exozodiacal dust distributions as optically thin as the solar system's are not yet possible with any technique around any type of star. In vestments have been made in ground-based exozodiacal dust measurements using the Keck Interferometer Nuller and the Large Binocular Telescope Interferometer (LBTI)
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From page 23... ...
The WFIRST/AFTA coronagraph will also demonstrate the use of a deformable mirror to remove telescope aberra tions and a tip-tilt system to remove telescope jitter. The performance of the complete system in space ultimately depends on the
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Finding 1-8: Whether the WFIRST/AFTA coronagraph satisfies the NWNH goal to establish exozodiacal light levels at a precision required to plan an Earth-like-exoplanet imaging mission is uncertain due to the immaturity of the coronagraph design and uncertainty in the ultimate performance. In addition to addressing some aspects of the NWNH medium-scale exoplanet technology development program, the AFTA coronagraph has the potential to ad vance general exoplanet science objectives.
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The short dashed and long dashed lines show, respectively, the contrast per resolution element of an exozodiacal dust disk with intensity 10 times the solar system viewed from 10 pc and 2 times the solar system viewed from 5 pc. SOURCE: Courtesy of NASA/JPL/Caltech.
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From page 26... ...
These planets will include some significantly farther from their parent stars than the exoplanets with transit spectra, and so the surfaces and atmospheres of these planets will not have been as strongly modified by stellar irradiation and will extend the observed exoplanet parameter space. At the current time, the sensitivity levels and observing program for the coronagraph are very uncertain, so it is not clear how much of this added science could be achieved in the 1 year allocated to coronagraph observations.
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