Hypervelocity stars in the Galactic bulge

Hypervelocity stars (HVSs) are stars moving away from the Galaxy at velocities exceeding the local escape velocity. Among the models proposed to explain their extreme speeds, the most widely accepted is the Hills (1988) mechanism, in which a supermassive black hole (SMBH) disrupts a binary system, ejecting one component as an HVS. Assuming HVSs originate from the Galactic Centre (GC), their spatial density should peak toward the inner regions of the Galaxy — the Galactic bulge. However, while a few HVSs have been identified in the Galactic halo, none have yet been confirmed in the bulge.

In this talk, I will present results from our ongoing search for HVSs in the Galactic bulge, combining optical (Gaia DR3) and infrared (VVV/VIRAC2) data. We have identified several promising HVS candidates that are being followed up spectroscopically.

HVSs inform us about the physical processes occurring near the GC, trace the Galactic potential, and constrain the GC-stellar populations properties and recent dynamical interactions with the SMBH. I will also highlight the challenges of identifying and characterizing such objects in highly crowded and reddened environments.