“…When the Compton wavelength of bosonic UDM is close to the same order as the BH radius, the energy and angular momentum of the BH would be transformed into the bosonic field, forming a macroscopic co-rotating boson cloud, which dissipates its energy through the emission of nearly monochromatic GWs. Therefore, the boson-BH system can act as a continuous GW source and is detectable by GW observations [42][43][44][48][49][50][51][52][53][54][55][56][57][58][59]. Until now, the null detection of GWs from the boson-BH systems has constrained bosonic UDM in various mass windows [11,20,43,48,52,53,58,[60][61][62].…”