Practical approaches to analyzing PTA data: Cosmic strings with six pulsars

Quelquejay Leclere, Hippolyte; Auclair, Pierre; Babak, Stanislav; Chalumeau, Aurélien; Steer, Danièle A.; Antoniadis, J.; Nielsen, A. S.Bak; Bassa, C. G.; Berthereau, A.; Bonetti, M.; Bortolas, E.; Brook, P. R.; Burgay, M.; Caballero, R. N.; Champion, D. J.; Chanlaridis, S.; Chen, S.; Cognard, I.; Desvignes, G.; Falxa, M.; Ferdman, R. D.; Franchini, A.; Gair, J. R.; Goncharov, B.; Graikou, E.; Grießmeier, J. M.; Guillemot, L.; Guo, Y. J.; Hu, H.; Iraci, F.; Izquierdo-Villalba, D.; Jang, J.; Jawor, J.; Janssen, G. H.; Jessner, A.; Karuppusamy, R.; Keane, E. F.; Keith, M. J.; Kramer, M.; Krishnakumar, M. A.; Lackeos, K.; Lee, K. J.; Liu, K.; Liu, Y.; Lyne, A. G.; McKee, J. W.; Main, R. A.; Mickaliger, M. B.; Niţu, I. C.; Parthasarathy, A.; Perera, B. B.P.; Perrodin, D.; Petiteau, A.; Porayko, N. K.; Possenti, A.; Samajdar, A.; Sanidas, S. A.; Sesana, A.; Shaifullah, G.; Speri, L.; Spiewak, R.; Stappers, B. W.; Susarla, S. C.; Theureau, G.; Tiburzi, C.; Van Der Wateren, E.; Vecchio, A.; K...

Abstract

We search for a stochastic gravitational wave background (SGWB) generated by a network of cosmic strings using six millisecond pulsars from Data Release 2 (DR2) of the European Pulsar Timing Array (EPTA). We perform a Bayesian analysis considering two models for the network of cosmic string loops, and compare it to a simple power-law model which is expected from the population of supermassive black hole binaries. Our main strong assumption is that the previously reported common red noise process is a SGWB. We find that the one-parameter cosmic string model is slightly favored over a power-law model thanks to its simplicity. If we assume a two-component stochastic signal in the data (supermassive black hole binary population and the signal from cosmic strings), we get a 95% upper limit on the string tension of log10(Gμ)<-9.9 (-10.5) for the two cosmic string models we consider. In extended two-parameter string models, we were unable to constrain the number of kinks. We test two approximate and fast Bayesian data analysis methods against the most rigorous analysis and find consistent results. These two fast and efficient methods are applicable to all SGWBs, independent of their source, and will be crucial for analysis of extended datasets.

Citation

Quelquejay Leclere, H., Auclair, P., Babak, S., Chalumeau, A., Steer, D. A., Antoniadis, J., …Wu, Z. (2023). Practical approaches to analyzing PTA data: Cosmic strings with six pulsars. Physical Review D, 108(12), Article 123527. https://doi.org/10.1103/PhysRevD.108.123527

• Journal Article Type: Article
• Acceptance Date: Nov 14, 2023
• Online Publication Date: Dec 15, 2023
• Publication Date: Dec 15, 2023
• Deposit Date: Jan 8, 2024
• Publicly Available Date: Jan 10, 2024
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0029
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 108
• Issue: 12
• Article Number: 123527
• DOI: https://doi.org/10.1103/PhysRevD.108.123527
• Public URL: https://hull-repository.worktribe.com/output/4500956