Exploring Pulsar Timing Precision: A Comparative Study of Polarization Calibration Methods for NANOGrav Data from the Green Bank Telescope

Abstract Pulsar timing array experiments have recently uncovered evidence for a nanohertz gravitational wave background by precisely timing an ensemble of millisecond pulsars. The next significant milestones for these experiments include characterizing the detected background with greater precision, identifying its source(s), and detecting continuous gravitational waves from individual supermassive black hole binaries. To achieve these objectives, generating accurate and precise times of arrival of pulses from pulsar observations is crucial. Incorrect polarization calibration of the observed pulsar profiles may introduce errors in the measured times of arrival. Further, previous studies have demonstrated that robust polarization calibration of pulsar profiles can reduce noise in the pulsar timing data and improve timing solutions. In this paper, we investigate and compare the impact of different polarization calibration methods on pulsar timing precision using three distinct calibration techniques: the Ideal Feed Assumption (IFA), Measurement Equation Modeling (MEM), and Measurement Equation Template Matching (METM). Three NANOGrav pulsars—PSRs J1643−1224, J1744−1134, and J1909−3744—observed with the 800 MHz and 1.5 GHz receivers at the Green Bank Telescope (GBT) are utilized for our analysis. Our findings reveal that all three calibration methods enhance timing precision compared to scenarios where no polarization calibration is performed. Additionally, among the three calibration methods, the IFA approach generally provides the best results for timing analysis of pulsars observed with the GBT receiver system. We attribute the comparatively poorer performance of the MEM and METM methods to potential instabilities in the reference noise diode coupled to the receiver and temporal variations in the profile of the reference pulsar, respectively.

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Publication Details

Journal
The Astrophysical Journal
Published
2024-12-01
DOI
https://doi.org/10.3847/1538-4357/ad8c24
Citations
3
Primary Topic
Pulsars and Gravitational Waves Research
Type
article
Field-Weighted Citation Impact
0.99

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article

Exploring Pulsar Timing Precision: A Comparative Study of Polarization Calibration Methods for NANOGrav Data from the Green Bank Telescope

H. Thankful Cromartie, M. A. McLaughlin, Nihan S. Pol, N. Garver-Daniels et al.
3 citations
The Astrophysical Journal
Pulsars and Gravitational Waves Research
0.99
article

Exploring Pulsar Timing Precision: A Comparative Study of Polarization Calibration Methods for NANOGrav Data from the Green Bank Telescope

H. Thankful Cromartie, M. A. McLaughlin, Nihan S. Pol, N. Garver-Daniels, Timothy Dolch, E. C. Ferrara, S. M. Ransom, David J. Nice, Sarah Burke-Spolaor, William Fiore, Michael T. Lam, Deborah C. Good, R. D. Ferdman, Haley M. Wahl, Joseph Glaser, Lankeswar Dey, Peter A. Gentile, Ryan S. Lynch, Ingrid H. Stairs, Timothy T. Pennucci, Duncan R. Lorimer, Paul R. Brook, Ross J. Jennings, Paul B. Demorest, R. Spiewak, Kevin Stovall, Megan L. Jones, Zaven Arzoumanian, Jing Luo, Cherry Ng, Megan E. DeCesar, Joseph K. Swiggum, Harsha Blumer, Emmanuel Fonseca, Justin A. Ellis
article en
3 citations

Abstract

Abstract Pulsar timing array experiments have recently uncovered evidence for a nanohertz gravitational wave background by precisely timing an ensemble of millisecond pulsars. The next significant milestones for these experiments include characterizing the detected background with greater precision, identifying its source(s), and detecting continuous gravitational waves from individual supermassive black hole binaries. To achieve these objectives, generating accurate and precise times of arrival of pulses from pulsar observations is crucial. Incorrect polarization calibration of the observed pulsar profiles may introduce errors in the measured times of arrival. Further, previous studies have demonstrated that robust polarization calibration of pulsar profiles can reduce noise in the pulsar timing data and improve timing solutions. In this paper, we investigate and compare the impact of different polarization calibration methods on pulsar timing precision using three distinct calibration techniques: the Ideal Feed Assumption (IFA), Measurement Equation Modeling (MEM), and Measurement Equation Template Matching (METM). Three NANOGrav pulsars—PSRs J1643−1224, J1744−1134, and J1909−3744—observed with the 800 MHz and 1.5 GHz receivers at the Green Bank Telescope (GBT) are utilized for our analysis. Our findings reveal that all three calibration methods enhance timing precision compared to scenarios where no polarization calibration is performed. Additionally, among the three calibration methods, the IFA approach generally provides the best results for timing analysis of pulsars observed with the GBT receiver system. We attribute the comparatively poorer performance of the MEM and METM methods to potential instabilities in the reference noise diode coupled to the receiver and temporal variations in the profile of the reference pulsar, respectively.

The Astrophysical JournalVol. 977(1)
Eötvös Loránd University (HU), University of East Anglia (GB), West Virginia University (US), Goddard Space Flight Center (US), National Academy of Sciences (US), University of British Columbia (CA), Rochester Institute of Technology (US), George Mason University (US), Lafayette College (US), University of Toronto (CA), National Academies of Sciences, Engineering, and Medicine (US), Vanderbilt University (US), National Radio Astronomy Observatory (US), University of Manchester (GB), Hillsdale College (US), Canadian Institute for Theoretical Astrophysics (CA), Eureka Scientific (US), University of Wisconsin–Milwaukee (US), University of Maryland, College Park (US), University of Montana (US), University of Birmingham (GB), Search for Extraterrestrial Intelligence (US)
National Science Foundation, National Aeronautics and Space Administration, Vanderbilt University, Canadian Institute for Advanced Research, West Virginia University, University of Toronto, Eötvös Loránd Tudományegyetem, Goddard Space Flight Center, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council, Office of Naval Research, U.S. Naval Research Laboratory
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Pulsars and Gravitational Waves Research
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