The Radius of PSR J0740+6620 from NICER with NICER Background Estimates

作     者：Salmi, Tuomo Vinciguerra, Serena Choudhury, Devarshi Riley, Thomas E. Watts, Anna L. Remillard, Ronald A. Ray, Paul S. Bogdanov, Slavko Guillot, Sebastien Arzoumanian, Zaven Chirenti, Cecilia Dittmann, Alexander J. Gendreau, Keith C. Ho, Wynn C.G. Miller, M. Coleman Morsink, Sharon M. Wadiasingh, Zorawar Wolff, Michael T. 

作者机构：Anton Pannekoek Institute for Astronomy University of Amsterdam Science Park 904 Amsterdam1090GE Netherlands MIT Kavli Institute for Astrophysics & Space Research MIT 70 Vassar Street CambridgeMA02139 United States Space Science Division U.S. Naval Research Laboratory WashingtonDC20375 United States Columbia Astrophysics Laboratory Columbia University 550 West 120th Street New YorkNY10027 United States Institut de Recherche en Astrophysique et Planétologie UPS-OMP CNRS CNES 9 avenue du Colonel Roche BP 44346 ToulouseF-31028 Cedex 4 France X-Ray Astrophysics Laboratory NASA Goddard Space Flight Center Code 662 GreenbeltMD20771 United States Department of Astronomy Joint Space-Science Institute University of Maryland College ParkMD20742-2421 United States Astroparticle Physics Laboratory NASA/GSFC GreenbeltMD20771 United States Center for Research and Exploration in Space Science and Technology NASA/GSFC GreenbeltMD20771 United States Center for Mathematics Computation and Cognition UFABC SP Santo André09210-170 Brazil Theoretical Division Los Alamos National Laboratory Los AlamosNM87545 United States Department of Physics and Astronomy Haverford College 370 Lancaster Avenue HaverfordPA19041 United States Department of Physics University of Alberta 4-183 CCIS EdmontonABT6G 2E1 Canada Department of Astronomy University of Maryland College ParkMD20742 United States Astrophysics Science Division NASA Goddard Space Flight Center GreenbeltMD20771 United States 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2022年

核心收录：

主　　题：Bayesian networks 

摘      要：We report a revised analysis for the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740+6620, studied previously with joint fits to NICER and XMM-Newton data by Riley et al. (2021) and Miller et al. (2021). We perform a similar Bayesian estimation for the pulse-profile model parameters, except that instead of fitting simultaneously the XMM-Newton data, we use the best available NICER background estimates to constrain the number of photons detected from the source. This approach eliminates any potential issues in the cross-calibration between these two instruments, providing thus an independent check of the robustness of the analysis. The obtained neutron star parameter constraints are compatible with the already published results, with a slight dependence on how conservative the imposed background limits are. A tighter lower limit causes the inferred radius to increase, and a tighter upper limit causes it to decrease. We also extend the study of the inferred emission geometry to examine the degree of deviation from antipodality of the hot regions. We show that there is a significant offset to an antipodal spot configuration, mainly due to the non-half-cycle azimuthal separation of the two emitting spots. The offset angle from the antipode is inferred to be above 25◦ with 84% probability. This seems to exclude a centered-dipolar magnetic field in PSR J0740+6620. Copyright © 2022, The Authors. All rights reserved.