The Astrophysical Journal (Jan 2024)
The NANOGrav 12.5-Year Data Set: Dispersion Measure Misestimations with Varying Bandwidths
- Sophia Valentina Sosa Fiscella,
- Michael T. Lam,
- Zaven Arzoumanian,
- Harsha Blumer,
- Paul R. Brook,
- H. Thankful Cromartie,
- Megan E. DeCesar,
- Paul B. Demorest,
- Timothy Dolch,
- Justin A. Ellis,
- Robert D. Ferdman,
- Elizabeth C. Ferrara,
- Emmanuel Fonseca,
- Nate Garver-Daniels,
- Peter A. Gentile,
- Deborah C. Good,
- Megan L. Jones,
- Duncan R. Lorimer,
- Jing Luo,
- Ryan S. Lynch,
- Maura A. McLaughlin,
- Cherry Ng,
- David J. Nice,
- Timothy T. Pennucci,
- Nihan S. Pol,
- Scott M. Ransom,
- Renée Spiewak,
- Ingrid H. Stairs,
- Kevin Stovall,
- Joseph K. Swiggum,
- Sarah J. Vigeland
Affiliations
- Sophia Valentina Sosa Fiscella
- ORCiD
- School of Physics and Astronomy , Rochester Institute of Technology, Rochester, NY 14623, USA; Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology , Rochester, NY 14623, USA
- Michael T. Lam
- ORCiD
- School of Physics and Astronomy , Rochester Institute of Technology, Rochester, NY 14623, USA; Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology , Rochester, NY 14623, USA; SETI Institute , 339 N Bernardo Avenue, Suite 200, Mountain View, CA 94043, USA
- Zaven Arzoumanian
- X-Ray Astrophysics Laboratory , NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA
- Harsha Blumer
- ORCiD
- Department of Physics and Astronomy, West Virginia University , P.O. Box 6315, Morgantown, WV 26506, USA; Center for Gravitational Waves and Cosmology, West Virginia University , Chestnut Ridge Research Building, Morgantown, WV 26505, USA
- Paul R. Brook
- ORCiD
- Institute for Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham , Edgbaston, Birmingham B15 2TT, UK
- H. Thankful Cromartie
- ORCiD
- Cornell Center for Astrophysics and Planetary Science and Department of Astronomy, Cornell University , Ithaca, NY 14853, USA
- Megan E. DeCesar
- ORCiD
- George Mason University , resident at the Naval Research Laboratory, Washington, DC 20375, USA
- Paul B. Demorest
- ORCiD
- National Radio Astronomy Observatory , 1003 Lopezville Road, Socorro, NM 87801, USA
- Timothy Dolch
- ORCiD
- Department of Physics , Hillsdale College, 33 E. College Street, Hillsdale, MI 49242, USA; Eureka Scientific , 2452 Delmer Street, Suite 100, Oakland, CA 94602-3017, USA
- Justin A. Ellis
- Bionic Health , 600 Park Offices Drive, Suite 140, Research Triangle Park, NC 27709, USA
- Robert D. Ferdman
- ORCiD
- School of Chemistry, University of East Anglia , Norwich, NR4 7TJ, UK
- Elizabeth C. Ferrara
- ORCiD
- Department of Astronomy, University of Maryland , College Park, MD 20742, USA; Center for Research and Exploration in Space Science and Technology , NASA/GSFC, Greenbelt, MD 20771, USA; NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA
- Emmanuel Fonseca
- ORCiD
- Department of Physics and Astronomy, West Virginia University , P.O. Box 6315, Morgantown, WV 26506, USA; Center for Gravitational Waves and Cosmology, West Virginia University , Chestnut Ridge Research Building, Morgantown, WV 26505, USA
- Nate Garver-Daniels
- ORCiD
- Department of Physics and Astronomy, West Virginia University , P.O. Box 6315, Morgantown, WV 26506, USA; Center for Gravitational Waves and Cosmology, West Virginia University , Chestnut Ridge Research Building, Morgantown, WV 26505, USA
- Peter A. Gentile
- ORCiD
- Department of Physics and Astronomy, West Virginia University , P.O. Box 6315, Morgantown, WV 26506, USA; Center for Gravitational Waves and Cosmology, West Virginia University , Chestnut Ridge Research Building, Morgantown, WV 26505, USA
- Deborah C. Good
- ORCiD
- Department of Physics, University of Connecticut , 196 Auditorium Road, U-3046, Storrs, CT 06269-3046, USA; Center for Computational Astrophysics , Flatiron Institute, 162 5th Avenue, New York, NY 10010, USA
- Megan L. Jones
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA
- Duncan R. Lorimer
- ORCiD
- Department of Physics and Astronomy, West Virginia University , P.O. Box 6315, Morgantown, WV 26506, USA; Center for Gravitational Waves and Cosmology, West Virginia University , Chestnut Ridge Research Building, Morgantown, WV 26505, USA
- Jing Luo
- ORCiD
- Department of Astronomy & Astrophysics, University of Toronto , 50 Saint George Street, Toronto, ON M5S 3H4, Canada
- Ryan S. Lynch
- ORCiD
- Green Bank Observatory , P.O. Box 2, Green Bank, WV 24944, USA
- Maura A. McLaughlin
- ORCiD
- Department of Physics and Astronomy, West Virginia University , P.O. Box 6315, Morgantown, WV 26506, USA; Center for Gravitational Waves and Cosmology, West Virginia University , Chestnut Ridge Research Building, Morgantown, WV 26505, USA
- Cherry Ng
- ORCiD
- Dunlap Institute for Astronomy and Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada
- David J. Nice
- ORCiD
- Department of Physics , Lafayette College, Easton, PA 18042, USA
- Timothy T. Pennucci
- ORCiD
- Institute of Physics and Astronomy , Eötvös Loránd University, Pázmány P.s. 1/A, 1117 Budapest, Hungary
- Nihan S. Pol
- ORCiD
- Department of Physics and Astronomy, Vanderbilt University , 2301 Vanderbilt Place, Nashville, TN 37235, USA
- Scott M. Ransom
- ORCiD
- National Radio Astronomy Observatory , 520 Edgemont Road, Charlottesville, VA 22903, USA
- Renée Spiewak
- ORCiD
- Jodrell Bank Centre for Astrophysics, University of Manchester , Manchester, M13 9PL, UK
- Ingrid H. Stairs
- ORCiD
- Department of Physics and Astronomy, University of British Columbia , 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada
- Kevin Stovall
- ORCiD
- National Radio Astronomy Observatory , 1003 Lopezville Road, Socorro, NM 87801, USA
- Joseph K. Swiggum
- ORCiD
- Department of Physics , Lafayette College, Easton, PA 18042, USA
- Sarah J. Vigeland
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA
- DOI
- https://doi.org/10.3847/1538-4357/ad2858
- Journal volume & issue
-
Vol. 966,
no. 1
p. 95
Abstract
Noise characterization for pulsar-timing applications accounts for interstellar dispersion by assuming a known frequency dependence of the delay it introduces in the times of arrival (TOAs). However, calculations of this delay suffer from misestimations due to other chromatic effects in the observations. The precision in modeling dispersion is dependent on the observed bandwidth. In this work, we calculate the offsets in infinite-frequency TOAs due to misestimations in the modeling of dispersion when using varying bandwidths at the Green Bank Telescope. We use a set of broadband observations of PSR J1643−1224, a pulsar with unusual chromatic timing behavior. We artificially restricted these observations to a narrowband frequency range, then used both the broad- and narrowband data sets to calculate residuals with a timing model that does not account for time variations in the dispersion. By fitting the resulting residuals to a dispersion model and comparing the fits, we quantify the error introduced in the timing parameters due to using a reduced frequency range. Moreover, by calculating the autocovariance function of the parameters, we obtained a characteristic timescale over which the dispersion misestimates are correlated. For PSR J1643−1224, which has one of the highest dispersion measures (DM) in the NANOGrav pulsar timing array, we find that the infinite-frequency TOAs suffer from a systematic offset of ∼22 μ s due to incomplete frequency sampling, with correlations over about one month. For lower-DM pulsars, the offset is ∼7 μ s. This error quantification can be used to provide more robust noise modeling in the NANOGrav data, thereby increasing the sensitivity and improving the parameter estimation in gravitational wave searches.
Keywords
- Millisecond pulsars
- Pulsars
- Interstellar medium
- Gravitational waves
- Pulsar timing method
- Timing variation methods
