New black hole mergers in the LIGO-Virgo O3 data from a gravitational wave search including higher-order harmonics
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1.
California Institute of Technology
Abstract
Nearly all of the previous gravitational wave (GW) searches in the LIGO-Virgo data included GW waveforms with only the dominant quadrupole mode, i.e., omitting higher-order harmonics which are predicted by general relativity. Based on the techniques developed in Wadekar et al. [1,2], we improve the IAS pipeline by (i) introducing higher harmonics in the GW templates, (ii) downweighting noise transients ('glitches') to improve the search sensitivity to high-mass and high-redshift binary black hole (BBH) mergers. We find 14 new BBH mergers with 0.53≤pastro≤0.88 on running our pipeline over the public LIGO-Virgo data from the O3 run (we use the detection threshold as pastro>0.5 following the approach of other pipelines). We also broadly recover the high-significance events from earlier catalogs, except some which were either vetoed or fell below our SNR threshold for trigger collection.
A few notable properties of our new candidate events are as follows. At >95\% credibility, 4 candidates have total masses in the IMBH range (i.e., above 100 M⊙), and 9 candidates have z>0.5. 9 candidates have median mass of the primary BH falling roughly within the pair instability mass gap, with the highest primary mass being 300−120+60M⊙. 5 candidates have median mass ratio q<0.5. Under a prior uniform in effective spin χeff, 6 candidates have χeff>0 at >95% credibility. We also find that including higher harmonics in our search raises the significance of a few previously reported marginal events (e.g., GW190711_030756). While our new candidate events have modest false alarm rates (≳1.6/yr), a population inference study including these can better inform the parameter space of BHs corresponding to the pair instability mass gap, high redshifts, positive effective spins and asymmetric mass ratios.
Acknowledgement
We thank Horng Sheng Chia, Ajith Parameswaran, Will Farr, Vishal Baibhav, Katerina Chatziioannou, Vicky Kalogera, Sylvia Biscoveanu, Amanda Farah, Daniel Holz, Salvatore Vitale, Tom Edwards, Zoehyr Doctor, Suvodip Mukherjee and Mukesh Singh for helpful discussions. DW gratefully acknowledges support from the Friends of the Institute for Advanced Study Membership and the Keck foundation. TV acknowledges support from NSF grants 2012086 and 2309360, the Alfred P. Sloan Foundation through grant number FG-2023-20470, the BSF through award number 2022136, and the Hellman Family Faculty Fellowship. MZ is supported by NSF 2209991 and NSF-BSF 2207583. BZ is supported by the Israel Science Foundation, NSF-BSF and by a research grant from the Willner Family Leadership Institute for the Weizmann Institute of Science. This research was also supported in part by the National Science Foundation under Grant No. NSF PHY-1748958. We also thank ICTS-TIFR for their hospitality during the completion of a part of this work.
This research has made use of data, software and/or web tools obtained from the Gravitational Wave Open
Science Center (https://www.gw-openscience.org/), a service of LIGO Laboratory, the LIGO Scientific Collaboration and the Virgo Collaboration. LIGO Laboratory and Advanced LIGO are funded by the United States National Science Foundation (NSF) as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the Max-Planck-Society (MPS), and the State of Niedersachsen/Germany for support of the construction of Advanced LIGO and construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. Virgo is funded, through the European Gravitational Observatory (EGO), by the French Centre National de Recherche Scientifique (CNRS), the Italian Istituto Nazionale di Fisica Nucleare (INFN) and the
Dutch Nikhef, with contributions by institutions from Belgium, Germany, Greece, Hungary, Ireland, Japan,
Monaco, Poland, Portugal, Spain.
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Additional details
- Caltech groups
- TAPIR, Walter Burke Institute for Theoretical Physics
- Publication Status
- Submitted