Eccentric search for Neutron star-black hole (NSBH) and binary neutron star (BNS) mergers within O3 advanced LIGO and advanced VIRGO data

[Rahul Dhurkunde]^{1, 2}, Alexander H. Nitz³,

<sub>1. Max-Planck-Institut for Gravitationsphysik (Albert-Einstein-Institut), D-30167 Hannover, Germany
2. Leibniz Universitat Hannover, D-30167 Hannover, Germany
3. Department of Physics, Syracuse University, Syracuse, NY 13244, USA</sub>

(Image credits: Soheb Mandhai)

Introduction

The possible formation histories of neutron star binaries remain unresolved by current gravitational-wave catalogs. The detection of an eccentric binary system could be vital in constraining compact binary formation models. We present the first search for aligned spin eccentric neutron star-black hole binaries (NSBH) and the most sensitive search for aligned-spin eccentric binary neutron star (BNS) systems using data from the third observing run of the advanced LIGO and advanced Virgo detectors. No new statistically significant candidates are found; we constrain the local merger rate to be less than 150 $\text{Gpc}^{-3}\text{Yr}^{-1}$ for binary neutron stars in the field, and, 50, 100, and 70 $\text{Gpc}^{-3}\text{Yr}^{-1}$ for neutron star-black hole binaries in globular clusters, hierarchical triples and nuclear clusters, respectively, at the 90$%$ confidence level if we assume that no sources have been observed from these populations. We predict the capabilities of upcoming and next-generation observatory networks; we investigate the ability of three LIGO (A#) detectors and Cosmic Explorer CE (20km) + CE (40km) to use eccentric binary observations for determining the formation history of neutron star binaries. We find that 2 -- 100 years of observation with three A# observatories are required before we observe clearly eccentric NSBH binaries; this reduces to only 10 days -- 1 year with the CE detector network. CE will observe tens to hundreds of measurably eccentric binaries from each of the formation models we consider.

A preprint version of the paper is available on arXiv. This release contains the following:

• Search
  • Configuration files for the search, template bank, and injections used for the analysis.
• Search results
  • List of top candidates
  • The search sensitivity as a function of mchirp and eccentricity (HDF5 files).
• Constraints
  • Population synthesis data -- Mchirp and eccentricity samples.
  • Noise ASDs used to compute the optimal SNRs for the idealized searches.
  • Jupyter-lab notebooks to obtain the 90 % upper limits on the local merger rate.
• Measurability analysis
  • Scripts to compute the simplified Bayesian inference.
  • Dictionary of measurable binary sources for given SNRs (keys).

** The simulated data for the idealized searches is not provided due to the file size limit on GITHUB. This can be made available upon reasonable requests

License and Citation

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