60 candidate high-velocity stars originating from the Sagittarius dwarf spheroidal galaxy in Gaia EDR3

TL;DR

This study identifies 60 candidate high-velocity stars likely originating from the Sagittarius dwarf galaxy using Gaia EDR3 data, revealing their possible tidal stripping and chemical similarities with Sgr stream stars.

Contribution

It provides the first comprehensive identification and orbital analysis of high-velocity stars from Sgr using Gaia EDR3, including hypervelocity candidates.

Findings

60 candidate high-velocity stars identified

Stars likely tidally stripped from Sgr galaxy

Two hypervelocity stars possibly produced by Hills mechanism

Abstract

Using proper motions from Gaia Early Data Release 3 (Gaia EDR 3) and radial velocities from several surveys, we identify 60 candidate high-velocity stars with total velocity greater than 75\% escape velocity that probably origin from Sagittarius dwarf spheroidal galaxy (Sgr) by orbital analysis. Sgr's gravity has little effect on the results and the Large Magellanic Cloud's gravity has non-negligible effect on only a few stars. The closest approach of these stars to the Sgr occurs when the Sgr passed its pericenter ($\sim$ 38.2 Myr ago), which suggest they were tidally stripped from the Sgr. The positions of these stars in the HR diagram and the chemical properties of 19 of them with available [Fe/H] are similar with the Sgr stream member stars. This is consistent with the assumption of their accretion origin. Two of the 60 are hypervelocity stars, which may also be produced by Hills mechanism.