Optimizing the U.S. Ground-Based Optical and Infrared Astronomy System (2015) / Chapter Skim
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2 Science from Major U.S. Ground-Based OIR Investments
2 Science from Major U.S. Ground-Based OIR Investments
Pages 10-23
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From page 10... ...
Cosmic dawn involves searching for the first stars, galaxies, and black holes and understanding the formation and early evolution of structure in the universe. In the realm of new worlds, astronomers seek nearby habitable planets and explore properties of exoplanetary systems and their disk progenitors, probe the formation and evolution of stars including the Sun, and seek to understand the details of gas-stellar processes and star formation histories across the full range of galaxies including the Milky Way.
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From page 11... ...
OIR System, it is not possible to review all of the exciting recent discoveries and breakthroughs, so instead a few highlights are presented to illustrate the breadth of the accomplishments and the progress being made on some of the key decadal science themes. A key goal of cosmic dawn research is to understand the first galaxies and their role in emitting ultraviolet radiation that reionized the universe during the first billion years after the Big Bang.
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From page 12... ...
In the past few years, several candidates for potentially habitable planets have been found both from ground-based radial velocity surveys and from NASA's Kepler mission, includ ing eight small planets orbiting G-type stars like the Sun.10 Another exoplanet, Kepler-186f (Figure 2.1) was inferred to be Earth-sized and orbiting within its M dwarf star's habitable zone.11 Observations with adaptive optics on Keck and speckle imaging on Gemini telescopes ruled out the possibility of a faint compan ion star mimicking the observed light curve dip, although Kepler observations supplemented by high-spatial-resolution speckle imaging on National Optical A stronomical Observatory's (NOAO's)
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From page 13... ...
Ground-based OIR surveys offer powerful probes of the physics of the universe. The Baryon Oscillation Spectroscopic Survey (BOSS)
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From page 14... ...
S . G r o u n d - B a s e d OIR A s t r o n o m y S y s t e m FIGURE 2.2 Image from GPI on Gemini South of Beta Pictoris b, a planet orbiting the star Beta ictoris P (masked out in the center of the image)
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From page 15... ...
3,500 Type Ia supernovae to probe the accelerated expansion of the universe. Now in its second year, the survey has, among its initial results,15 discovered 1,000 high-redshift supernovae and scores of high-redshift galaxy clusters, made weaklensing maps of clusters, discovered new outer solar system bodies, and discovered ultra-faint dwarf galaxies that may account for some local dark matter.16 These projects will be complemented by the Hobby-Eberly Telescope Dark Energy Experi ment17 (HETDEX)
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From page 16... ...
Dynamical cloud features on Saturn, Neptune, and Uranus have been studied with adaptive optics on telescopes such as Keck, Gemini, and Subaru.19 Trans-Neptunian Objects (TNOs) , which are primitive bodies that provide insight on conditions in the early solar system, have been the subject of many ground- and space-based surveys to understand their properties and distribu tion.20 The Next Generation Virgo Cluster Survey, a high-resolution study using the MegaPrime camera on the CFHT 3.6-meter telescope, discovered nearly 100 new objects, including a very distant TNO that suggests an extensive population of more than 11,000 such objects in the inner Oort Cloud.21 2.2 Positioning the OIR System to Complement Non-OIR Astronomy OIR astronomy spans only a few octaves of the electromagnetic spectrum, but often anchors astronomy that originates at other wavelengths.
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From page 17... ...
and the Keck 10-meter with adaptive optics.23 The infrared sensitivity to warmer material complements the radio/ submillimeter sensitivity to cold material, providing a complete picture of the constituents of these systems. Radio-variable objects identified in radio time domain surveys, such as M stars, active galactic nuclei (AGN)
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From page 18... ...
As in the radio regime, wide-field multi-object spectroscopy is needed to identify and characterize sources such as AGNs and galaxy clusters found in deep X-ray surveys. These studies will be complemented by the Astro-H mission to be launched by the Japan Aerospace Exploration Agency in 2016, with NASA contributing a high-resolution soft X-ray spectrometer for measuring gas near black holes, active galaxies, and supernovae.
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From page 19... ...
There does not appear to be an outstanding unmet need for a specific groundbased OIR capability to complement present X-ray and gamma-ray missions, nor would planned missions appear to require more than the generic capabilities likely to be implemented over the course of the next decade. Gravitational Wave Studies Gravitational waves are perturbations in spacetime caused by accelerating masses, just as electromagnetic waves are emitted by accelerating charges.
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From page 20... ...
Technology for a future ESA space mission to detect gravitational waves will be tested with a planned launch of the LISA Pathfinder (named after a previously planned mission, the Laser Interferometer Space Antenna)
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From page 21... ...
2.3 Future Synergies between Ground based and Space-based OIR Facilities Powerful science comes from combining space-based observations with data from the OIR System. This combination has proved profoundly productive -- sensitive imaging from unique instruments in space combined with imaging surveys and spectra from large telescopes on the ground has revealed the nature of faint objects both near (such as field brown dwarfs)
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From page 22... ...
The legacy of TESS will be a catalog of the nearest and brightest stars that host transiting exoplanets, which should be excellent targets for detailed investigations in the coming decades. The Kepler 2 mission of the Kepler spacecraft is providing a preview of TESS science and generating planet candidates along the ecliptic plane.
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From page 23... ...
Its science mission is to probe dark matter and dark energy by mapping cosmic structure through weak gravitational lensing using optical imaging complementary to the near-IR imaging of WFIRST. Euclid will also obtain near-IR spectroscopy and photometry and study baryon acoustic oscillations in the near-IR using detectors provided by NASA.
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