The LIGO-Virgo collaboration reported in their third run the coalescence event GW190814 involving a $2.6M_{\odot }$ object with a $23M_{\odot }$ black hole. In this article we study the conditions under which Thorne-Żytkow objects (TŻOs) can be connected to that type of event. We evaluate first the rate of appearance of TŻOs in the local Universe. Under the assumption that TŻOs eventually become low mass gap black holes we evaluate how those black holes end up in binaries with other stellar mass black holes and compare to the reported rate for GW190814-type of events ($1–23{\mathrm{Gpc}}^{-3}{\mathrm{yr}}^{-1}$). We find that TŻOs in dense stellar clusters can not explain the LIGO-Virgo rate without a TŻO population in the field providing a dominant contribution. We also find that TŻOs formed within hierarchical triple systems in the field with the third more distant star being the progenitor of a stellar mass black hole may be able to give a rate comparable to that of GW190814-type events. In that case, future observations should discover mergers between stellar mass and low mass gap black holes, with the lower mass spanning the entire low mass gap range.

• Received 23 June 2021
• Revised 9 January 2022
• Accepted 6 June 2022

DOI:https://doi.org/10.1103/PhysRevD.105.123022