Seminar Series Abstracts: Oct 3, 2024

New black hole mergers from a search pipeline for gravitational wave signals with higher-order harmonics

Modeled searches for gravitational wave (GW) signals from merging binary systems use a family of template waveforms to define a search space. Nearly all of previous modeled GW searches in the LIGO-Virgo data used templates containing only the dominant quadrupole mode, i.e., omitted higher-order harmonics in the signals which are predicted by general relativity. We will describe a new efficient method to include higher modes in the search pipeline without significantly increasing the computational cost or substantially degrading the search sensitivity. We will also discuss a few new methods to down-weight noise transients ("glitches") and improve the search sensitivity to high-mass binary black hole (BBH) mergers. Introducing these changes in the IAS pipeline, we detect ~10 new BBH mergers in the LIGO-VIRGO O3 data. Some of the new BH binary detections have astrophysically interesting properties such as BH masses in the IMBH and pair-instability mass gap ranges, asymmetric mass ratios, positive effective spins and high-redshifts (1<z<2).