Searching for Exotrojans in Pulsar Systems

Abstract Trojan asteroids are found in the equilateral triangle Lagrange points of the Sun–Jupiter system in a great number, although they also exist less prolifically in other parts of the solar system. Despite up to planetary mass Trojans being predicted in extrasolar systems (i.e., exotrojans), they remain unconfirmed, although strong candidate evidence has emerged recently. For the first time, we extend the search for exotrojans to radio pulsars with low-mass (∼0.01 M ⊙ ) companions using accurately measured pulse times of arrival. With techniques developed for detecting the reflex motion of a star due to a librating Trojan, we place ∼1 M ⊕ upper mass constraints on potential exotrojans around eight pulsars observed in the NANOGrav 15 yr dataset. We find weak evidence consistent with ∼2–4 M J exotrojans in the PSR J0023+0923 and PSR J1705−1903 binary systems, although the signals likely have a different, unknown source. We also place a libration-independent upper mass constraint of ∼8 M J on exotrojans in the PSR J1641+8049 system by looking for an inconsistency between the times of superior conjunction as measured by optical light curves and those predicted by radio timing. These results offer initial observational constraints on the existence of exotrojans around pulsars, while their possible formation mechanisms remain unexplored.

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Publication Details

Journal
The Astrophysical Journal
Published
2026-03-13
DOI
https://doi.org/10.3847/1538-4357/ae4317
Primary Topic
Pulsars and Gravitational Waves Research
Type
article
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article

Searching for Exotrojans in Pulsar Systems

H. Thankful Cromartie, Natasha McMann, S. V. Zharikov, Bradley W. Meyers et al.
The Astrophysical Journal
Pulsars and Gravitational Waves Research
article

Searching for Exotrojans in Pulsar Systems

H. Thankful Cromartie, Natasha McMann, S. V. Zharikov, Bradley W. Meyers, Alexander McEwen, M. A. McLaughlin, Carl Schmiedekamp, Jacob Taylor, Nihan S. Pol, Timothy Dolch, E. C. Ferrara, S. M. Ransom, Akash Anumarlapudi, David J. Nice, David L. Kaplan, Anne M. Archibald, William Fiore, Gabriel E. Freedman, Michael T. Lam, Deborah C. Good, Haley M. Wahl, Abhimanyu Susobhanan, Joseph Glaser, Lankeswar Dey, Nate Garver-Daniels, Peter A. Gentile, Ryan S. Lynch, Ingrid H. Stairs, Brent J. Shapiro-Albert, Kathryn Crowter, Timothy T. Pennucci, Duncan R. Lorimer, P. T. Baker, Paul R. Brook, Ross J. Jennings, A. Yu. Kirichenko, Ann Schmiedekamp, Paul B. Demorest, Jeffrey S. Hazboun, Kevin Stovall, Matthew T. Kerr, Paul S. Ray, Benetge B. P. Perera, Megan L. Jones, Zaven Arzoumanian, Jing Luo, Cherry Ng, Gabriella Agazie, Megan E. DeCesar, Joseph K. Swiggum, Emmanuel Fonseca, H. A. Radovan
article en

Abstract

Abstract Trojan asteroids are found in the equilateral triangle Lagrange points of the Sun–Jupiter system in a great number, although they also exist less prolifically in other parts of the solar system. Despite up to planetary mass Trojans being predicted in extrasolar systems (i.e., exotrojans), they remain unconfirmed, although strong candidate evidence has emerged recently. For the first time, we extend the search for exotrojans to radio pulsars with low-mass (∼0.01 M ⊙ ) companions using accurately measured pulse times of arrival. With techniques developed for detecting the reflex motion of a star due to a librating Trojan, we place ∼1 M ⊕ upper mass constraints on potential exotrojans around eight pulsars observed in the NANOGrav 15 yr dataset. We find weak evidence consistent with ∼2–4 M J exotrojans in the PSR J0023+0923 and PSR J1705−1903 binary systems, although the signals likely have a different, unknown source. We also place a libration-independent upper mass constraint of ∼8 M J on exotrojans in the PSR J1641+8049 system by looking for an inconsistency between the times of superior conjunction as measured by optical light curves and those predicted by radio timing. These results offer initial observational constraints on the existence of exotrojans around pulsars, while their possible formation mechanisms remain unexplored.

The Astrophysical JournalVol. 1000(1)
Eötvös Loránd University (HU), University of North Carolina at Chapel Hill (US), Leibniz University Hannover (DE), West Virginia University (US), Texas Tech University (US), United States Naval Research Laboratory (US), Goddard Space Flight Center (US), Pennsylvania State University (US), Oregon State University (US), National Academy of Sciences (US), Widener University (US), University of British Columbia (CA), Rochester Institute of Technology (US), George Mason University (US), Universidad Autónoma de Baja California (MX), Lafayette College (US), University of Toronto (CA), National Academies of Sciences, Engineering, and Medicine (US), Vanderbilt University (US), Curtin University (AU), National Radio Astronomy Observatory (US), West Virginia University Hospitals (US), Abington Memorial Hospital (US), Hillsdale College (US), Canadian Institute for Theoretical Astrophysics (CA), Max Planck Institute for Gravitational Physics (DE), Eureka Scientific (US), International Centre for Radio Astronomy Research (AU), University of Wisconsin–Milwaukee (US), University of Puerto Rico-Mayaguez (PR), University of Maryland, College Park (US), University of Montana (US), University of Birmingham (GB), Newcastle University (GB), Search for Extraterrestrial Intelligence (US), University of Puerto Rico at Arecibo (PR), Universidad Nacional Autónoma de México (MX)
Openalex Percentile: Top 99%
Pulsars and Gravitational Waves Research
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