Gaia reference frame amid quasar variability and proper motion patterns in the data
R. K. Bachchan, D. Hobbs, L. Lindegren

TL;DR
This paper assesses Gaia's ability to establish a precise optical celestial reference frame using quasars and galaxies, accounting for variability and proper motion patterns, and explores methods to measure Solar System acceleration and cosmic velocity.
Contribution
It models quasar and galaxy distributions, analyzes the impact of variability on reference frame accuracy, and proposes techniques to measure Solar System acceleration and cosmic velocity.
Findings
Quasar variability does not significantly disturb the reference frame when statistically averaged.
Non-uniform quasar sky distribution can cause correlations degrading the solution.
Potential to determine the Hubble parameter through galaxy redshift-dependent apparent drift.
Abstract
Gaia's very accurate astrometric measurements will allow the International Celestial Reference Frame (ICRF) to be improved by a few orders of magnitude in the optical. Several sets of quasars are used to define a kinematically stable non-rotating reference frame with the barycentre of the Solar System as its origin. Gaia will also observe a large number of galaxies which could obtain accurate positions and proper motions although they are not point-like. The optical stability of the quasars is critical and we investigate how accurately the reference frame can be recovered. Various proper motion patterns are also present in the data, the best known is caused by the acceleration of the Solar System Barycentre, presumably, towards the Galactic centre. We review some other less-well-known effects that are not part of standard astrometric models. We model quasars and galaxies using realistic…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
