Long-term Astrometric Monitoring of the Galactic Center Magnetar PSR J1745−2900

We present new astrometric observations of the Galactic center magnetar PSR J1745−2900 with the Very Long Baseline Array. Combined with previously published measurements in 10 epochs that spanned 477 days, the complete data set consists of 25 epochs and 41 independent measurements that span 1984 day...

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Main Authors: Geoffrey C. Bower, Adam T. Deller, Paul B. Demorest, Jason Dexter, Andreas Brunthaler, Gregory Desvignes, Ralph P. Eatough, Heino Falcke, Ciriaco Goddi, Michael Kramer, F. Yusef-Zadeh
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Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/ade0be
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author Geoffrey C. Bower
Adam T. Deller
Paul B. Demorest
Jason Dexter
Andreas Brunthaler
Gregory Desvignes
Ralph P. Eatough
Heino Falcke
Ciriaco Goddi
Michael Kramer
F. Yusef-Zadeh
author_facet Geoffrey C. Bower
Adam T. Deller
Paul B. Demorest
Jason Dexter
Andreas Brunthaler
Gregory Desvignes
Ralph P. Eatough
Heino Falcke
Ciriaco Goddi
Michael Kramer
F. Yusef-Zadeh
author_sort Geoffrey C. Bower
collection DOAJ
description We present new astrometric observations of the Galactic center magnetar PSR J1745−2900 with the Very Long Baseline Array. Combined with previously published measurements in 10 epochs that spanned 477 days, the complete data set consists of 25 epochs and 41 independent measurements that span 1984 days. These data constrain the proper motion to an accuracy of ≲2% and set an upper limit on the absolute value of the magnetar’s acceleration of ≲(0.4, 0.2) mas yr ^−2 in the two celestial coordinates, consistent with the maximum value of ∼0.03 mas yr ^−2 expected for an orbit around Sgr A*. Future measurements have the potential to detect the acceleration of PSR J1745−2900 due to Sgr A* should PSR J1745−2900 rebrighten. We consider several potential sources of systematic variations in the astrometric residuals after fitting for standard parameters, including refractive wander, changes in the structure of Sgr A*, and the presence of an unseen binary companion. While a stellar companion model can be fit to the astrometric data, pulse period measurements are inconsistent with that model. No changes in the apparent image size of the magnetar were detected over the duration of these observations, indicating a lack of change in the properties of the line-of-sight scattering during this period. We also show that the upper limit to the mean core shift of Sgr A* is consistent with expectations for a compact jet or symmetric accretion flow.
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spelling doaj-art-6bdbb9a42e534770beb34c46cd3799d32025-08-20T03:51:18ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01988216810.3847/1538-4357/ade0beLong-term Astrometric Monitoring of the Galactic Center Magnetar PSR J1745−2900Geoffrey C. Bower0https://orcid.org/0000-0003-4056-9982Adam T. Deller1https://orcid.org/0000-0001-9434-3837Paul B. Demorest2https://orcid.org/0000-0002-6664-965XJason Dexter3https://orcid.org/0000-0003-3903-0373Andreas Brunthaler4https://orcid.org/0000-0003-4468-761XGregory Desvignes5https://orcid.org/0000-0003-3922-4055Ralph P. Eatough6https://orcid.org/0000-0001-6196-4135Heino Falcke7https://orcid.org/0000-0002-2526-6724Ciriaco Goddi8https://orcid.org/0000-0002-2542-7743Michael Kramer9https://orcid.org/0000-0002-4175-2271F. Yusef-Zadeh10East Asian Observatory , 660 N. A’ohoku Pl., Hilo, HI 96720, USA ; gbower@asiaa.sinica.edu.tw; Academia Sinica Institute of Astronomy and Astrophysics , 645 N. A’ohoku Pl., Hilo, HI 96720, USA; Department of Physics and Astronomy, University of Hawaii at Manoa , 2505 Correa Road, Honolulu, HI 96822, USACentre for Astrophysics and Supercomputing, Swinburne University of Technology , John St., Hawthorn, VIC 3122, AustraliaNational Radio Astronomy Observatory , P.O. Box O, Socorro, NM 87801, USAJILA and Department of Astrophysical and Planetary Sciences, University of Colorado , Boulder, CO 80309, USAMax-Planck-Institut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn, GermanyMax-Planck-Institut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn, Germany; LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université , Université de Paris, 5 place Jules Janssen, F-92195 Meudon, FranceMax-Planck-Institut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn, Germany; National Astronomical Observatories, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100101, People’s Republic of ChinaDepartment of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University , P.O. Box 9010, 6500 GL Nijmegen, The NetherlandsUniversidade de São Paulo , Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Departamento de Astronomia, São Paulo, SP 05508-090, Brazil; Dipartimento di Fisica, Universitá degli Studi di Cagliari , SP Monserrato-Sestu km 0.7, I-09042 Monserrato, Italy; INAF—Osservatorio Astronomico di Cagliari , via della Scienza 5, I-09047 Selargius (CA), Italy; INFN, Sezione di Cagliari, Cittadella Univ. , I-09042 Monserrato (CA), ItalyMax-Planck-Institut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn, GermanyDepartment of Physics and Astronomy, CIERA, Northwestern University , 2145 Sheridan Road, Evanston, IL 60207, USAWe present new astrometric observations of the Galactic center magnetar PSR J1745−2900 with the Very Long Baseline Array. Combined with previously published measurements in 10 epochs that spanned 477 days, the complete data set consists of 25 epochs and 41 independent measurements that span 1984 days. These data constrain the proper motion to an accuracy of ≲2% and set an upper limit on the absolute value of the magnetar’s acceleration of ≲(0.4, 0.2) mas yr ^−2 in the two celestial coordinates, consistent with the maximum value of ∼0.03 mas yr ^−2 expected for an orbit around Sgr A*. Future measurements have the potential to detect the acceleration of PSR J1745−2900 due to Sgr A* should PSR J1745−2900 rebrighten. We consider several potential sources of systematic variations in the astrometric residuals after fitting for standard parameters, including refractive wander, changes in the structure of Sgr A*, and the presence of an unseen binary companion. While a stellar companion model can be fit to the astrometric data, pulse period measurements are inconsistent with that model. No changes in the apparent image size of the magnetar were detected over the duration of these observations, indicating a lack of change in the properties of the line-of-sight scattering during this period. We also show that the upper limit to the mean core shift of Sgr A* is consistent with expectations for a compact jet or symmetric accretion flow.https://doi.org/10.3847/1538-4357/ade0bePulsarsRadio pulsarsBinary pulsarsGalactic centerBlack holesInterstellar scattering
spellingShingle Geoffrey C. Bower
Adam T. Deller
Paul B. Demorest
Jason Dexter
Andreas Brunthaler
Gregory Desvignes
Ralph P. Eatough
Heino Falcke
Ciriaco Goddi
Michael Kramer
F. Yusef-Zadeh
Long-term Astrometric Monitoring of the Galactic Center Magnetar PSR J1745−2900
The Astrophysical Journal
Pulsars
Radio pulsars
Binary pulsars
Galactic center
Black holes
Interstellar scattering
title Long-term Astrometric Monitoring of the Galactic Center Magnetar PSR J1745−2900
title_full Long-term Astrometric Monitoring of the Galactic Center Magnetar PSR J1745−2900
title_fullStr Long-term Astrometric Monitoring of the Galactic Center Magnetar PSR J1745−2900
title_full_unstemmed Long-term Astrometric Monitoring of the Galactic Center Magnetar PSR J1745−2900
title_short Long-term Astrometric Monitoring of the Galactic Center Magnetar PSR J1745−2900
title_sort long term astrometric monitoring of the galactic center magnetar psr j1745 2900
topic Pulsars
Radio pulsars
Binary pulsars
Galactic center
Black holes
Interstellar scattering
url https://doi.org/10.3847/1538-4357/ade0be
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