Candidate Hypervelocity Red Clump Stars in the Galactic Bulge Found Using the VVV and Gaia Surveys

TL;DR

This paper introduces a novel method to identify hypervelocity red clump stars in the Galactic bulge using Gaia and VVV survey data, leading to the discovery of seven candidates and estimating their production rate.

Contribution

It presents a new approach utilizing red clump giants as distance indicators to find hypervelocity stars in the Galactic bulge, based on combined Gaia and VVV data.

Findings

Discovered seven candidate hypervelocity red clump stars.

Estimated the production rate of hypervelocity RC stars from the SMBH.

Demonstrated the potential for future surveys to find more hypervelocity stars.

Abstract

We propose a new way to search for hypervelocity stars in the Galactic bulge, by using red clump (RC) giants, that are good distance indicators. The 2nd Gaia Data Release and the near-IR data from the VISTA Variables in the Via Lactea (VVV) Survey led to the selection of a volume limited sample of 34 bulge RC stars. A search in this combined data set leads to the discovery of seven candidate hypervelocity red clump stars in the Milky Way bulge. Based on this search we estimate the total production rate of hypervelocity RC stars from the central supermassive black hole (SMBH) to be $N_{HVRC} = 3.26 \times 10^{-4} $ yr$^{-1}$. This opens up the possibility of finding larger samples of hypervelocity stars in the Galactic bulge using future surveys, closer to their main production site, if they are originated by interactions of binaries with the central SMBH.