New search pipeline for gravitational waves with higher-order harmonics

Current GW searches could be overlooking some black hole mergers in LVK data because most template banks include waveforms with only the quadrupole mode (l,m)=(2,2), i.e., omitting higher modes (HM) such as (l,m)=(3,3), (4,4). In particular, templates with HM can be important for detecting high-mass systems (especially in the IMBH regime) with asymmetric mass-ratios. I will present an approach of using a combination of post-Newtonian formulae and machine learning tools to model HM waveforms based on information contained in the quadrupole waveform. This enables reusing a quadrupole-only template bank to efficiently search for GWs with HM. I will also discuss some preliminary results on searching for BBH events in the LIGO-VIRGO O3 data with our new effectual HM template-bank modeling method.