The second data release from the European Pulsar Timing Array II. Customised pulsar noise models for spatially correlated gravitational waves
Abstract
The nanohertz gravitational wave background (GWB) is expected to be an aggregate signal of an ensemble of gravitational waves emitted predominantly by a large population of coalescing supermassive black hole binaries in the centres of merging galaxies. Pulsar timing arrays, ensembles of extremely stable pulsars, are the most precise experiments capable of detecting this background. However, the subtle imprints that the GWB induces on pulsar timing data are obscured by many sources of noise. These must be carefully characterized to increase the sensitivity to the GWB. In this paper, we present a novel technique to estimate the optimal number of frequency coefficients for modelling achromatic and chromatic noise and perform model selection. We also incorporate a new model to fit for scattering variations in the pulsar timing package temponest and created realistic simulations of the European Pulsar Timing Array (EPTA) datasets that allowed us to test the efficacy of our noise modelling algorithms. We present an in-depth analysis of the noise properties of 25 millisecond pulsars (MSPs) that form the second data release (DR2) of the EPTA and investigate the effect of incorporating low-frequency data from the Indian PTA collaboration. We use enterprise and temponest packages to compare noise models with those reported with the EPTA DR1. We find that, while in some pulsars we can successfully disentangle chromatic from achromatic noise owing to the wider frequency coverage in DR2, in others the noise models evolve in a more complicated way. We also find evidence of long-term scattering variations in PSR J16003053. Through our simulations, we identify intrinsic biases in our current noise analysis techniques and discuss their effect on GWB searches. The results presented here directly help improve sensitivity to the GWB and are already being used as part of global PTA efforts.
Keywords
Cite
@article{arxiv.2306.16225,
title = {The second data release from the European Pulsar Timing Array II. Customised pulsar noise models for spatially correlated gravitational waves},
author = {J. Antoniadis and P. Arumugam and S. Arumugam and S. Babak and M. Bagchi and A. S. Bak Nielsen and C. G. Bassa and A. Bathula and A. Berthereau and M. Bonetti and E. Bortolas and P. R. Brook and M. Burgay and R. N. Caballero and A. Chalumeau and D. J. Champion and S. Chanlaridis and S. Chen and I. Cognard and S. Dandapat and D. Deb and S. Desai and G. Desvignes and N. Dhanda-Batra and C. Dwivedi and M. Falxa and R. D. Ferdman and A. Franchini and J. R. Gair and B. Goncharov and A. Gopakumar and E. Graikou and J. -M. Grießmeier and L. Guillemot and Y. J. Guo and Y. Gupta and S. Hisano and H. Hu and F. Iraci and D. Izquierdo-Villalba and J. Jang and J. Jawor and G. H. Janssen and A. Jessner and B. C. Joshi and F. Kareem and R. Karuppusamy and E. F. Keane and M. J. Keith and D. Kharbanda and T. Kikunaga and N. Kolhe and M. Kramer and M. A. Krishnakumar and K. Lackeos and K. J. Lee and K. Liu and Y. Liu and A. G. Lyne and J. W. McKee and Y. Maan and R. A. Main and M. B. Mickaliger and I. C. Niţu and K. Nobleson and A. K. Paladi and A. Parthasarathy and B. B. P. Perera and D. Perrodin and A. Petiteau and N. K. Porayko and A. Possenti and T. Prabu and H. Quelquejay Leclere and P. Rana and A. Samajdar and S. A. Sanidas and A. Sesana and G. Shaifullah and J. Singha and L. Speri and R. Spiewak and A. Srivastava and B. W. Stappers and M. Surnis and S. C. Susarla and A. Susobhanan and K. Takahashi and P. Tarafdar and G. Theureau and C. Tiburzi and E. van der Wateren and A. Vecchio and V. Venkatraman Krishnan and J. P. W. Verbiest and J. Wang and L. Wang and Z. Wu},
journal= {arXiv preprint arXiv:2306.16225},
year = {2023}
}
Comments
20 pages, 6 figures, 9 tables