Projects per year
Abstract
The orbital eccentricity of a merging binary black hole leaves an imprint on the associated gravitationalwave signal that can reveal whether the binary formed in isolation or in a dynamical environment, such as the core of a dense star cluster. We present measurements of the eccentricity of 26 binary black hole mergers in the second LIGOVirgo gravitationalwave transient catalog, updating the total number of binary black holes analyzed for orbital eccentricity to 36. Using the SEOBNRE waveform, we find the data for GW190620A are poorly explained by the zeroeccentricity hypothesis (frequentist pvalue 0.1%). Using a loguniform prior on eccentricity, the eccentricity at 10 Hz for GW190620A is constrained to e10. 0.05 (0.1) at 74% (65%) credibility. With this loguniform prior, we obtain a 90% credible lower eccentricity limit of 0.001, while assuming a uniform prior leads the data to prefer e10. 0.11 at 90% credibility. This is the second measurement of a binary black hole system with statistical support for nonzero eccentricity; the intermediatemass black hole merger GW190521 was the first. Interpretation of these two events is currently complicated by waveform systematics; we are unable to simultaneously model the effects of relativistic precession and eccentricity. However, if these two events are, in fact, eccentric mergers, then there are potentially many more dynamically assembled mergers in the LIGOVirgo catalog without measurable eccentricity; ∼27% of the observed LIGOVirgo binaries may have been assembled dynamically in dense stellar environments (95% credibility).
Original language  English 

Article number  L31 
Number of pages  12 
Journal  The Astrophysical Journal Letters 
Volume  921 
Issue number  2 
DOIs  
Publication status  Published  10 Nov 2021 
Keywords
 Astrophysical black holes
 Compact binary stars
 Gravitational wave astronomy
 Gravitational wave sources
 Gravitational waves
 LIGO
Projects
 1 Active

ARC Centre of Excellence for Gravitational Wave Discovery
Bailes, M., McClelland, D. E., Levin, Y., Blair, D. G., Scott, S. M., Ottaway, D. J., Melatos, A., Veitch, P. J., Wen, L., Shaddock, D. A., Slagmolen, B. J. J., Zhao, C., Evans, R. J., Ju, L., Galloway, D., Thrane, E., Hurley, J. R., Coward, D. M., Cooke, J., Couch, W., Hobbs, G. B., Reitze, D., Rowan, S., Cai, R., Adhikari, R. X., Danzmann, K., Mavalvala, N., Kulkarni, S. R., Kramer, M., Branchesi, M., Gehrels, N., Weinstein, A. J. R., Steeghs, D., Bock, D. & Lasky, P.
Monash University – Internal University Contribution, Monash University – Internal Department Contribution
1/01/17 → 31/03/24
Project: Research