Astro2020 Activity, Project of State of the Profession Consideration (APC) White Paper: All Sky Near Infrared Space Astrometry. State of the Profession Considerations: Development of Scanning NIR Detectors for Astronomy
Journal Article - Open Access
MIT Lincoln Laboratory Lexington United States
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Gaia is a revolutionary space mission developed by ESA and is delivering 5 parameter astrometry, photometry and radial velocities over the whole sky with astrometric accuracies down to a few tens of micro-arcseconds. A weakness of Gaia is that it only operates at optical wavelengths. However, much of the Galactic centre and the spiral arm regions, important for certain studies, are obscured by interstellar extinction and this makes it difficult for Gaia to deeply probe. This problem can be overcome by switching to the Near Infra-Red NIRbut this is not possible with silicon CCDs. Additionally, to scan the entire sky and make global absolute parallax measurements the spacecraft must have a constant rotation and this requires the detectors operate in Time Delayed Integration TDI mode or similar. A clear improvement on Gaia is to go into the NIR and such a proposal has been made to ESA Hobbs, et al., 2016, 1 and ESA subsequently studied the mission concept in detail GaiaNIR Study to enlarge the achievements of Gaia with NIR survey. The ESA study found that a TDI solution would give similar accuracies as Gaia despite doubling the wavelength range. However such TDI technology for NIR detectors scarcely exists mainly because it is not possible to transfer electrons from pixel to pixel in typical materials used for NIR detectors. The science cases for Gaia NIR have been outlined by Hobbs, et al., 2016,1 and in a proposed collaboration on this project with the US recently submitted as anAstro2020 Science white paper on All-Sky Near Infrared Space Astrometry, McArthur, et al., 2019, 2. Additionally a further white paper on this topic will be submitted to ESAs continuation call of Cosmic Vision, called Voyage 2050, in August of this year. The science return from such a mission is very promising but a solution to the technology problem of implementing a TDI like solution in large format NIR detectors must now be found.