Forming Lower-mass-gap Black Holes in Dense Star Clusters

Frequent dynamical encounters in globular clusters significantly enhance the production of multi-messenger phenomena. It is now well established that globular clusters host robust populations of compact objects, including low-mass X-ray binaries, millisecond pulsars, and gravitational wave sources. The evolution of these compact objects is intricately linked within dense star clusters. Black holes impact the dynamics of neutron stars. In turn, the collapse of neutron stars through accretion or mergers could play a crucial role in forming low-mass black holes. Specifically, the existence of black holes in the so-called lower mass gap (about 2-5 solar mass) has long been debated. Recently, however, a lower-mass-gap candidate was identified in a Galactic globular cluster. In this talk, I will illustrate the dynamical evolution of black holes and neutron stars in dense star clusters and show the formation pathways of lower-mass-gap black holes and their observable binaries.