2023/12/11 by Wadekar, Digvijay, Roulet, Javier, Venumadhav, Tejaswi +5 · 12 citations
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Astrophysical Phenomena (astro-ph.HE) #Instrumentation and Methods for Astrophysics (astro-ph.IM)
paper · doi:10.48550/arxiv.2312.06631
Nearly all of the previous gravitational wave (GW) searches in the LIGO-Virgo data included GW waveforms with only the dominant quadrupole harmonic, i.e., omitting higher-order harmonics which are predicted by general relativity. We improved the IAS pipeline by efficiently introducing higher harmonics in the GW templates using the techniques in Wadekar et al. [1, 2]. Using the IAS-HM pipeline on the public LIGO-Virgo data from the O3 run, we find 11 new candidate BBH mergers with 0.52≤ pastro≤ 0.88 (we use the detection threshold as the astrophysical probability, pastro, being over 0.5, following the approach of other pipelines). We broadly recover the high-significance events from earlier catalogs, except a few which were vetoed. We also find that including higher harmonics in our search raises the significance of a few previously reported marginal events (e.g., GW190711030756). A few notable properties of our new candidate events are as follows. At >95% credibility, 4 candidates have primary masses in the intermediate-mass black hole (IMBH) range (i.e., above ∼100 M_\odot). 5 candidates have median mass ratio q ≤ 0.5. 5 candidates have median redshift z ≥ 0.8. 3 candidates have non-zero χ\rm eff at >95% credibility. While our new candidate events have modest false alarm rates (\gtrsim 1.5 /yr), a population inference study including these can better inform the parameter space of BHs corresponding to the pair instability mass gap, high redshifts and asymmetric mass ratios.