Decadal Survey 2020 White Papers Led by IPAC Scientists

Direct Imaging and Spectroscopy of Exoplanets with the James Webb Space Telescope
Beichman, Charles; Barrado, David; Belikov, Ruslan and 35 more

Coronagraphic imaging and direct spectroscopy of young planets with JWST will add new insights into our understanding of the formation and evolution of exoplanets. This paper focuses on how JWST will add to our knowledge of young giant planets located at orbits beyond a few AU for the closest stars and a few 10s of AU for more distant ones.

Toward Finding Earth 2.0: Masses and Orbits of Small Planets with Extreme Radial Velocity Precision
Ciardi, David; Bean, Jacob; Burt, Jennifer and 9 more

Having discovered that Earth-sized planets are common, we are now embarking on a journey to determine if Earth-like planets are also common. To achieve this forward-looking goal, we must determine the masses and orbits of the planets; as such, the development of high quality precision radial velocity instruments and facilities is needed.

Mapping out the time-evolution of exoplanet processes
Christiansen, Jessie; Beichman, Charles; Ciardi, David R. and 1 more

In this white paper we identify predicted correlations, particularly trends in exoplanet populations, radii, orbits and atmospheres with host star age, that will allow us to begin identifying the dominant processes governing the formation and evolution of exoplanet systems.

Understanding Exoplanet Atmospheres with UV Observations I: NUV and Blue/Optical
Christiansen, Jessie; Barclay, Thomas; Fossati, Luca and 6 more

In this white paper we focus on the science case for exoplanet observations at near-UV/blue optical wavelengths. Scattering information encoded in at these wavelengths can distinguish the cause of muted spectral features. These wavelengths also capture atmospheric escape processes, and help characterize mass loss from exoplanet atmospheres.

Warm H2 as a probe of massive accretion and feedback through shocks and turbulence across cosmic time
Appleton, Philip; Armus, Lee; Boulanger, Francois and 22 more

We discuss the importance of the direct detection of molecular hydrogen (through redshifted mid-IR lines, and UV absorption) at high redshift as a probe of massive accretion and feedback processes in galaxies and protogalaxies and to potentially detect gas cooling and feeding the most massive and metal-free dark matter halos to z = 12.

Synergizing Deep Field Programs Across Multiple Surveys
Capak, Peter; Scolnic, Dan; Davidzon, Iary

A critical component of many past, present and future astronomical surveys is a dedicated deep field program. We argue these should be explicitly coordinated and considered in project design to maximize the scientific output of these important observations.

Opportunities in Time-domain Stellar Astrophysics with the NASA Near-Earth Object Camera (NEOCam)
Kirkpatrick, J. Davy; Metchev, Stanimir A.; Hillenbrand, Lynne A. and 11 more

NEOCam will provide valuable data for the discovery and characterization of cold brown dwarfs, exoplanet analogs with weather variations, pre-main sequence variables, infrared-only transients, and more. For a relatively small investment, NASA can realize the full potential of NEOCam data by providing additional data products and transient alerting.

The Need for Infrared Astrometry of Brown Dwarfs in the Post-Gaia Era
Kirkpatrick, J. Davy; Abdurrahman, Fatima; Best, William M. and 9 more

Brown dwarf research in the next decade will be reliant on extending high- precision astrometry in wavelength and temporal coverage. Future astrometry will enable measures of the low-mass cutoff of star formation, allow for the discovery of cold brown dwarf analogs to cold (exo)planets, and enable mass measurements for single and binary systems.

On the Origins of the Initial Mass Function
Paladini, Roberta; Povich, Matthew; Armus, Lee and 10 more

In order to establish if the IMF and CMF are Universal, it is necessary to: 1) perform multi-wavelength large-scale imaging and spectroscopic surveys; 2) require an angular resolution of 0.1 arcsec in the optical/near-IR and 5 arcsec in the far-IR; 3) achieve far-IR sensitivities to probe 0.1 M cores at 2-3 kpc.

Cosmology in the 2020s Needs Precision and Accuracy: The Case for Euclid/LSST/WFIRST Joint Survey Processing
Chary, Ranga Ram; Armus, Lee; Faisst, Andreas and 7 more

Cosmological breakthroughs in the 2020s will arise from measuring the redshift evolution of dark energy, resolving the tension in the expansion rate of the Universe, and understanding the impact of dark matter on galaxy substructure. Joint processing of Euclid/LSST/WFIRST data provides the most compelling, economical and tractable path forward.

Illuminating the dark universe with a very high density galaxy redshift survey over a wide area
Wang, Yun; Bean, Rachel; Behroozi, Peter and 27 more

A very high number density galaxy redshift survey over a wide area (HD GRS Wide) spanning the redshift range of 0.5<z<4 using the same tracer, carried out using massively parallel wide field multi-object slit spectroscopy from space, will provide definitive dark energy measurements with minimal observational systematics by design.