Discovery and timing of ten new millisecond pulsars in the globular cluster Terzan 5

• Published in: Astronomy and astrophysics (Berlin) 2024-06, Vol.686, p.A166
• Main Authors: Padmanabh, P. V., Ransom, S. M., Freire, P. C. C., Ridolfi, A., Taylor, J. D., Choza, C., Clark, C. J., Abbate, F., Bailes, M., Barr, E. D., Buchner, S., Burgay, M., DeCesar, M. E., Chen, W., Corongiu, A., Champion, D. J., Dutta, A., Geyer, M., Hessels, J. W. T., Kramer, M., Possenti, A., Stairs, I. H., Stappers, B. W., Venkatraman Krishnan, V., Vleeschower, L., Zhang, L.
• Format: Article
• Language: English
• Subjects: Binary stars; Clusters; Globular clusters; Millisecond pulsars; Neutron stars; Neutrons; Orbits; Pulsars; Radio telescopes; Stellar evolution; X ray imagery
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/202449303

We report the discovery of ten new pulsars in the globular cluster Terzan 5 as part of the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project. We observed Terzan 5 at L -band (856–1712 MHz) with the MeerKAT radio telescope for four hours on two epochs, and performed acceleration searches of 45 out of 288 tied-array beams covering the core of the cluster. We obtained phase-connected timing solutions for all ten discoveries, covering nearly two decades of archival observations from the Green Bank Telescope for all but one. Highlights include PSR J1748−2446ao which is an eccentric ( e = 0.32) wide-orbit (orbital period P b = 57.55 d) system. We were able to measure the rate of advance of periastron ( ω̇ ) for this system allowing us to determine a total mass of 3.17 ± 0.02 M ⊙ . With a minimum companion mass ( M c ) of ∼0.8 M ⊙ , PSR J1748−2446ao is a candidate double neutron star (DNS) system. If confirmed to be a DNS, it would be the fastest spinning pulsar ( P = 2.27 ms) and the longest orbital period measured for any known DNS system. PSR J1748−2446ap has the second highest eccentricity for any recycled pulsar ( e ∼ 0.905) and for this system we can measure the total mass (1.997 ± 0.006 M ⊙ ) and estimate the pulsar and companion masses, (1.700 −0.045 +0.015 M ⊙ and 0.294 −0.014 +0.046 M ⊙ , respectively). PSR J1748−2446ar is an eclipsing redback (minimum M c ∼ 0.34 M ⊙ ) system whose properties confirm it to be the counterpart to a previously published source identified in radio and X-ray imaging. We were also able to detect ω̇ for PSR J1748−2446au leading to a total mass estimate of 1.82 ± 0.07 M ⊙ and indicating that the system is likely the result of Case A Roche lobe overflow. With these discoveries, the total number of confirmed pulsars in Terzan 5 is 49, the highest for any globular cluster so far. These discoveries further enhance the rich set of pulsars known in Terzan 5 and provide scope for a deeper understanding of binary stellar evolution, cluster dynamics and ensemble population studies.