# The High Time Resolution Universe Pulsar Survey - XIII. PSR J1757-1854, the most accelerated binary pulsar

Research output: Contribution to journalArticle

• External authors:
• A. D. Cameron
• D. J. Champion
• M. Kramer
• M. Bailes
• E. D. Barr
• C. G. Bassa
• S. Bhandari
• N. D. R. Bhat
• M. Burgay
• S. Burke-Spolaor
• R. P. Eatough
• C. M. L. Flynn
• P. C. C. Freire
• A. Jameson
• S. Johnston
• R. Karuppusamy
• L. Levin
• D. R. Lorimer
• A. G. Lyne
• M. A. McLaughlin
• C. Ng
• E. Petroff
• A. Possenti
• A. Ridolfi
• B. W. Stappers
• W. van Straten
• T. M. Tauris
• C. Tiburzi
• N. Wex

## Abstract

We report the discovery of PSR J1757$-$1854, a 21.5-ms pulsar in a highly-eccentric, 4.4-h orbit around a neutron star (NS) companion. PSR J1757$-$1854 exhibits some of the most extreme relativistic parameters of any known pulsar, including the strongest relativistic effects due to gravitational-wave (GW) damping, with a merger time of 76 Myr. Following a 1.6-yr timing campaign, we have measured five post-Keplerian (PK) parameters, yielding the two component masses ($m_\text{p}=1.3384(9)\,\text{M}_\odot$ and $m_\text{c}=1.3946(9)\,\text{M}_\odot$) plus three tests of general relativity (GR), which the theory passes. The larger mass of the NS companion provides important clues regarding the binary formation of PSR J1757$-$1854. With simulations suggesting 3-$\sigma$ measurements of both the contribution of Lense-Thirring precession to the rate of change of the semi-major axis and the relativistic deformation of the orbit within $\sim7-9$ years, PSR J1757$-$1854 stands out as a unique laboratory for new tests of gravitational theories.