Measurements of weak gravity in wide binaries from Bayesian orbit modeling: current results and prospects with upcoming data
by
Kyu-Hyun Chae(Sejong University)
→
Asia/Seoul
CTPU Seminar room
CTPU Seminar room
Description
Recently published statistical analyses of wide binaries from the Gaia DR3 database were performed only with the sky-projected (transverse) velocities. I describe a new method of measuering gravity in wide binaries from Bayesian orbit modeling with both transverse and line-of-sight (longitudinal, radial) veolcities. This method first infers gravity individually from each wide binary taking into account all measurement uncertainties and then statistically combines a number of individual probability density functions (PDFs) to obtain a consolidated distribution in an acceleration range. This method accurately reproduces Newtonian gravity for wide binaries in a high internal gravity regime (>10 nm per second squared). For wide binaries in a low internal gravity regime (< 1 nm per second squared), the relative velocities in the pairs are small and thus individual PDFs are quite broad based on the currently available Gaia radial velocities data. Nevertheless, when PDFs of more than 100 wide binaries in the low accelartion regime are statistically combined, the consolidated distribution shows a >4sigma deviation from the Newtonian prediction in promising agreement with MOND-based modified gravity. Observations and observation proposals are going on to accurately measure radial velocities. When accurate radial velocities are available in the future, the nature of gravity in the low-acceleration regime can be accurately characterized.
