Refined Mass and Geometric Measurements of the High-mass PSR J0740+6620

• Published in: Astrophysical journal. Letters Vol. 915; no. 1; p. L12
• Main Authors: Fonseca, E., Cromartie, H. T., Pennucci, T. T., Ray, P. S., Kirichenko, A. Yu, Ransom, S. M., Demorest, P. B., Stairs, I. H., Arzoumanian, Z., Guillemot, L., Parthasarathy, A., Kerr, M., Cognard, I., Baker, P. T., Blumer, H., Brook, P. R., DeCesar, M., Dolch, T., Dong, F. A., Ferrara, E. C., Fiore, W., Garver-Daniels, N., Good, D. C., Jennings, R., Jones, M. L., Kaspi, V. M., Lam, M. T., Lorimer, D. R., Luo, J., McEwen, A., McKee, J. W., McLaughlin, M. A., McMann, N., Meyers, B. W., Naidu, A., Ng, C., Nice, D. J., Pol, N., Radovan, H. A., Shapiro-Albert, B., Tan, C. M., Tendulkar, S. P., Swiggum, J. K., Wahl, H. M., Zhu, W. W.
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center The American Astronomical Society 01.07.2021; American Astronomical Society; IOP Publishing; Bristol : IOP Publishing
• Subjects: Astronomy; Astrophysics; Binary pulsars; Compact objects; Differential rotation; Galactic rotation; General relativity; Hydrogen; Neutron stars; Optical observations; Orbits; Physics; Pulsars; Relativistic effects; Sciences of the Universe; Secular variations; Statistical methods; Time lag; Time measurement; White dwarf stars; General Relativity; Compact Objects; Binary Pulsars; Neutron Stars; Pulsars
• ISSN: 2041-8205; 2041-8213
• DOI: 10.3847/2041-8213/ac03b8

We report results from continued timing observations of PSR J0740+6620, a high-mass, 2.8 ms radio pulsar in orbit with a likely ultracool white dwarf companion. Our data set consists of combined pulse arrival-time measurements made with the 100 m Green Bank Telescope and the Canadian Hydrogen Intensity Mapping Experiment telescope. We explore the significance of timing-based phenomena arising from general relativistic dynamics and variations in pulse dispersion. When using various statistical methods, we find that combining∼1.5 yr of additional, high-cadence timing data with previous measurements confirms and improves on previous estimates of relativistic effects within the PSR J0740+6620 system, with the pulsar mass=-+mM2.08p0.070.07 M (68.3% credibility) determined by the relativistic Shapiro time delay. For the first time, we measure secular variation in the orbital period and argue that this effect arises from apparent acceleration due to significant transverse motion. After incorporating contributions from Galactic differential rotation and off-plane acceleration in the Galactic potential, we obtain a model-dependent distance of=-+d1.140.150.17kpc (68.3% credibility). This improved distance confirms the ultracool nature of the white dwarf companion determined from recent optical observations. We discuss the prospects for future observations with next-generation facilities, which will likely improve the precision on mp for J0740+6620 by an order of magnitude within the next few years