The Astrophysical Journal Letters (Jan 2024)
The NANOGrav 15 yr Data Set: Search for Transverse Polarization Modes in the Gravitational-wave Background
- Gabriella Agazie,
- Akash Anumarlapudi,
- Anne M. Archibald,
- Zaven Arzoumanian,
- Jeremy Baier,
- Paul T. Baker,
- Bence Bécsy,
- Laura Blecha,
- Adam Brazier,
- Paul R. Brook,
- Sarah Burke-Spolaor,
- Rand Burnette,
- Robin Case,
- J. Andrew Casey-Clyde,
- Maria Charisi,
- Shami Chatterjee,
- Tyler Cohen,
- James M. Cordes,
- Neil J. Cornish,
- Fronefield Crawford,
- H. Thankful Cromartie,
- Kathryn Crowter,
- Megan E. DeCesar,
- Dallas DeGan,
- Paul B. Demorest,
- Timothy Dolch,
- Brendan Drachler,
- Elizabeth C. Ferrara,
- William Fiore,
- Emmanuel Fonseca,
- Gabriel E. Freedman,
- Nate Garver-Daniels,
- Peter A. Gentile,
- Joseph Glaser,
- Deborah C. Good,
- Kayhan Gültekin,
- Jeffrey S. Hazboun,
- Ross J. Jennings,
- Aaron D. Johnson,
- Megan L. Jones,
- Andrew R. Kaiser,
- David L. Kaplan,
- Luke Zoltan Kelley,
- Matthew Kerr,
- Joey S. Key,
- Nima Laal,
- Michael T. Lam,
- William G. Lamb,
- T. Joseph W. Lazio,
- Natalia Lewandowska,
- Tingting Liu,
- Duncan R. Lorimer,
- Jing Luo,
- Ryan S. Lynch,
- Chung-Pei Ma,
- Dustin R. Madison,
- Alexander McEwen,
- James W. McKee,
- Maura A. McLaughlin,
- Natasha McMann,
- Bradley W. Meyers,
- Chiara M. F. Mingarelli,
- Andrea Mitridate,
- Priyamvada Natarajan,
- Cherry Ng,
- David J. Nice,
- Stella Koch Ocker,
- Ken D. Olum,
- Timothy T. Pennucci,
- Benetge B. P. Perera,
- Nihan S. Pol,
- Henri A. Radovan,
- Scott M. Ransom,
- Paul S. Ray,
- Joseph D. Romano,
- Alexander Saffer,
- Shashwat C. Sardesai,
- Ann Schmiedekamp,
- Carl Schmiedekamp,
- Kai Schmitz,
- Brent J. Shapiro-Albert,
- Xavier Siemens,
- Joseph Simon,
- Magdalena S. Siwek,
- Ingrid H. Stairs,
- Daniel R. Stinebring,
- Kevin Stovall,
- Jerry P. Sun,
- Abhimanyu Susobhanan,
- Joseph K. Swiggum,
- Jacob A. Taylor,
- Stephen R. Taylor,
- Jacob E. Turner,
- Caner Unal,
- Michele Vallisneri,
- Sarah J. Vigeland,
- Haley M. Wahl,
- Caitlin A. Witt,
- Olivia Young,
- The NANOGrav Collaboration
Affiliations
- Gabriella Agazie
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]
- Akash Anumarlapudi
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]
- Anne M. Archibald
- ORCiD
- Newcastle University , NE1 7RU, UK
- Zaven Arzoumanian
- X-Ray Astrophysics Laboratory, NASA Goddard Space Flight Center , Code 662, Greenbelt, MD 20771, USA
- Jeremy Baier
- Department of Physics, Oregon State University , Corvallis, OR 97331, USA
- Paul T. Baker
- ORCiD
- Department of Physics and Astronomy, Widener University , One University Place, Chester, PA 19013, USA
- Bence Bécsy
- ORCiD
- Department of Physics, Oregon State University , Corvallis, OR 97331, USA
- Laura Blecha
- ORCiD
- Physics Department, University of Florida , Gainesville, FL 32611, USA
- Adam Brazier
- ORCiD
- Cornell Center for Astrophysics and Planetary Science and Department of Astronomy, Cornell University , Ithaca, NY 14853, USA; Cornell Center for Advanced Computing, Cornell University , Ithaca, NY 14853, USA
- Paul R. Brook
- ORCiD
- Institute for Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham , Edgbaston, Birmingham B15 2TT, UK
- Sarah Burke-Spolaor
- 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
- Rand Burnette
- Department of Physics, Oregon State University , Corvallis, OR 97331, USA
- Robin Case
- Department of Physics, Oregon State University , Corvallis, OR 97331, USA
- J. Andrew Casey-Clyde
- ORCiD
- Department of Physics, University of Connecticut , 196 Auditorium Road, U-3046, Storrs, CT 06269-3046, USA
- Maria Charisi
- ORCiD
- Department of Physics and Astronomy, Vanderbilt University , 2301 Vanderbilt Place, Nashville, TN 37235, USA
- Shami Chatterjee
- ORCiD
- Cornell Center for Astrophysics and Planetary Science and Department of Astronomy, Cornell University , Ithaca, NY 14853, USA
- Tyler Cohen
- ORCiD
- Department of Physics, New Mexico Institute of Mining and Technology , 801 Leroy Place, Socorro, NM 87801, USA
- James M. Cordes
- ORCiD
- Cornell Center for Astrophysics and Planetary Science and Department of Astronomy, Cornell University , Ithaca, NY 14853, USA
- Neil J. Cornish
- ORCiD
- Department of Physics, Montana State University , Bozeman, MT 59717, USA
- Fronefield Crawford
- ORCiD
- Department of Physics and Astronomy , Franklin & Marshall College, P.O. Box 3003, Lancaster, PA 17604, USA
- H. Thankful Cromartie
- ORCiD
- Cornell Center for Astrophysics and Planetary Science and Department of Astronomy, Cornell University , Ithaca, NY 14853, USA
- Kathryn Crowter
- ORCiD
- Department of Physics and Astronomy, University of British Columbia , 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada
- Megan E. DeCesar
- ORCiD
- George Mason University , resident at the Naval Research Laboratory, Washington, DC 20375, USA
- Dallas DeGan
- ORCiD
- Department of Physics, Oregon State University , Corvallis, OR 97331, 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
- Brendan Drachler
- 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
- 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
- William Fiore
- 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
- 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
- Gabriel E. Freedman
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]
- 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
- Joseph Glaser
- 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
- Kayhan Gültekin
- ORCiD
- Department of Astronomy and Astrophysics, University of Michigan , Ann Arbor, MI 48109, USA
- Jeffrey S. Hazboun
- ORCiD
- Department of Physics, Oregon State University , Corvallis, OR 97331, USA
- Ross J. Jennings
- 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
- Aaron D. Johnson
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]; Division of Physics, Mathematics, and Astronomy, California Institute of Technology , Pasadena, CA 91125, 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 [email protected]
- Andrew R. Kaiser
- 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
- David L. Kaplan
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]
- Luke Zoltan Kelley
- ORCiD
- Department of Astronomy, University of California , Berkeley, 501 Campbell Hall #3411, Berkeley, CA 94720, USA
- Matthew Kerr
- ORCiD
- Space Science Division, Naval Research Laboratory , Washington, DC 20375-5352, USA
- Joey S. Key
- ORCiD
- University of Washington Bothell , 18115 Campus Way NE, Bothell, WA 98011, USA
- Nima Laal
- ORCiD
- Department of Physics, Oregon State University , Corvallis, OR 97331, 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
- William G. Lamb
- ORCiD
- Department of Physics and Astronomy, Vanderbilt University , 2301 Vanderbilt Place, Nashville, TN 37235, USA
- T. Joseph W. Lazio
- Jet Propulsion Laboratory, California Institute of Technology , 4800 Oak Grove Drive, Pasadena, CA 91109, USA
- Natalia Lewandowska
- ORCiD
- Department of Physics, State University of New York at Oswego , Oswego, NY 13126, USA
- Tingting Liu
- 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
- 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
- Chung-Pei Ma
- ORCiD
- Department of Astronomy, University of California , Berkeley, 501 Campbell Hall #3411, Berkeley, CA 94720, USA; Department of Physics, University of California , Berkeley, CA 94720, USA
- Dustin R. Madison
- ORCiD
- Department of Physics, University of the Pacific , 3601 Pacific Avenue, Stockton, CA 95211, USA
- Alexander McEwen
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]
- James W. McKee
- ORCiD
- E.A. Milne Centre for Astrophysics, University of Hull , Cottingham Road, Kingston-upon-Hull, HU6 7RX, UK; Centre of Excellence for Data Science, Artificial Intelligence and Modeling (DAIM), University of Hull , Cottingham Road, Kingston-upon-Hull, HU6 7RX, UK
- 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
- Natasha McMann
- ORCiD
- Department of Physics and Astronomy, Vanderbilt University , 2301 Vanderbilt Place, Nashville, TN 37235, USA
- Bradley W. Meyers
- ORCiD
- Department of Physics and Astronomy, University of British Columbia , 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada; International Centre for Radio Astronomy Research, Curtin University , Bentley, WA 6102, Australia
- Chiara M. F. Mingarelli
- 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; Department of Physics, Yale University , New Haven, CT 06520, USA
- Andrea Mitridate
- ORCiD
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
- Priyamvada Natarajan
- ORCiD
- Department of Astronomy, Yale University , 52 Hillhouse Avenue, New Haven, CT 06511, USA; Black Hole Initiative, Harvard University , 20 Garden Street, Cambridge, MA 02138, 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
- Stella Koch Ocker
- ORCiD
- Cornell Center for Astrophysics and Planetary Science and Department of Astronomy, Cornell University , Ithaca, NY 14853, USA
- Ken D. Olum
- ORCiD
- Institute of Cosmology, Department of Physics and Astronomy, Tufts University , Medford, MA 02155, USA
- Timothy T. Pennucci
- ORCiD
- Institute of Physics and Astronomy, Eötvös Loránd University , Pázmány P.s. 1/A, 1117 Budapest, Hungary
- Benetge B. P. Perera
- ORCiD
- Arecibo Observatory , HC3 Box 53995, Arecibo, PR 00612, USA
- Nihan S. Pol
- ORCiD
- Department of Physics and Astronomy, Vanderbilt University , 2301 Vanderbilt Place, Nashville, TN 37235, USA
- Henri A. Radovan
- ORCiD
- Department of Physics, University of Puerto Rico , Mayagüez, PR 00681, USA
- Scott M. Ransom
- ORCiD
- National Radio Astronomy Observatory , 520 Edgemont Road, Charlottesville, VA 22903, USA
- Paul S. Ray
- ORCiD
- Space Science Division, Naval Research Laboratory , Washington, DC 20375-5352, USA
- Joseph D. Romano
- ORCiD
- Department of Physics, Texas Tech University , Box 41051, Lubbock, TX 79409, USA
- Alexander Saffer
- 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
- Shashwat C. Sardesai
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]
- Ann Schmiedekamp
- ORCiD
- Department of Physics , Penn State Abington, Abington, PA 19001, USA
- Carl Schmiedekamp
- ORCiD
- Department of Physics , Penn State Abington, Abington, PA 19001, USA
- Kai Schmitz
- ORCiD
- Institute for Theoretical Physics, University of Münster , 48149 Münster, Germany
- Brent J. Shapiro-Albert
- 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; Giant Army, 915A 17th Avenue, Seattle WA 98122, USA
- Xavier Siemens
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]; Department of Physics, Oregon State University , Corvallis, OR 97331, USA
- Joseph Simon
- ORCiD
- Department of Astrophysical and Planetary Sciences, University of Colorado , Boulder, CO 80309, USA
- Magdalena S. Siwek
- ORCiD
- Center for Astrophysics, Harvard University , 60 Garden Street, Cambridge, MA 02138, USA
- Ingrid H. Stairs
- ORCiD
- Department of Physics and Astronomy, University of British Columbia , 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada
- Daniel R. Stinebring
- ORCiD
- Department of Physics and Astronomy, Oberlin College , Oberlin, OH 44074, USA
- Kevin Stovall
- ORCiD
- National Radio Astronomy Observatory , 1003 Lopezville Road, Socorro, NM 87801, USA
- Jerry P. Sun
- ORCiD
- Department of Physics, Oregon State University , Corvallis, OR 97331, USA
- Abhimanyu Susobhanan
- ORCiD
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-milwaukee , P.O. Box 413, Milwaukee, WI 53201, USA [email protected]
- Joseph K. Swiggum
- ORCiD
- Department of Physics, Lafayette College , Easton, PA 18042, USA
- Jacob A. Taylor
- ORCiD
- Department of Physics, Oregon State University , Corvallis, OR 97331, USA
- Stephen R. Taylor
- ORCiD
- Department of Physics and Astronomy, Vanderbilt University , 2301 Vanderbilt Place, Nashville, TN 37235, USA
- Jacob E. Turner
- 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
- Caner Unal
- ORCiD
- Department of Physics, Ben-Gurion University of the Negev , Be’er Sheva 84105, Israel; Feza Gursey Institute, Bogazici University , Kandilli, 34684, Istanbul, Turkey
- Michele Vallisneri
- ORCiD
- Division of Physics, Mathematics, and Astronomy, California Institute of Technology , Pasadena, CA 91125, USA; Jet Propulsion Laboratory, California Institute of Technology , 4800 Oak Grove Drive, Pasadena, CA 91109, 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 [email protected]
- Haley M. Wahl
- 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
- Caitlin A. Witt
- ORCiD
- Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University , Evanston, IL 60208, USA; Adler Planetarium, 1300 S. DuSable Lake Shore Drive, Chicago, IL 60605, USA
- Olivia Young
- 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
- The NANOGrav Collaboration
- Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology , Rochester, NY 14623, USA
- DOI
- https://doi.org/10.3847/2041-8213/ad2a51
- Journal volume & issue
-
Vol. 964,
no. 1
p. L14
Abstract
Recently we found compelling evidence for a gravitational-wave background with Hellings and Downs (HD) correlations in our 15 yr data set. These correlations describe gravitational waves as predicted by general relativity, which has two transverse polarization modes. However, more general metric theories of gravity can have additional polarization modes, which produce different interpulsar correlations. In this work, we search the NANOGrav 15 yr data set for evidence of a gravitational-wave background with quadrupolar HD and scalar-transverse (ST) correlations. We find that HD correlations are the best fit to the data and no significant evidence in favor of ST correlations. While Bayes factors show strong evidence for a correlated signal, the data does not strongly prefer either correlation signature, with Bayes factors ∼2 when comparing HD to ST correlations, and ∼1 for HD plus ST correlations to HD correlations alone. However, when modeled alongside HD correlations, the amplitude and spectral index posteriors for ST correlations are uninformative, with the HD process accounting for the vast majority of the total signal. Using the optimal statistic, a frequentist technique that focuses on the pulsar-pair cross-correlations, we find median signal-to-noise ratios of 5.0 for HD and 4.6 for ST correlations when fit for separately, and median signal-to-noise ratios of 3.5 for HD and 3.0 for ST correlations when fit for simultaneously. While the signal-to-noise ratios for each of the correlations are comparable, the estimated amplitude and spectral index for HD are a significantly better fit to the total signal, in agreement with our Bayesian analysis.
Keywords
