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A gamma-ray pulsar timing array constrains the nanohertz gravitational wave background

2022; American Association for the Advancement of Science; Volume: 376; Issue: 6592 Linguagem: Inglês

10.1126/science.abm3231

1095-9203

M. Ajello, W. B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, A. Berretta, Bhaswati Bhattacharyya, E. Bissaldi, R. D. Blandford, E. D. Bloom, R. Bonino, P. Bruel, R. Buehler, Eric Burns, S. Buson, R. A. Cameron, P. A. Caraveo, E. Cavazzuti, N. Cibrario, S. Ciprini, C. J. Clark, I. Cognard, Javier Coronado-Blázquez, M. Crnogorčević, H. Thankful Cromartie, Kathryn Crowter, S. Cutini, F. D’Ammando, S. de Gaetano, F. de Palma, S. W. Digel, Niccolò Di Lalla, F. Dirirsa, L. Di Venere, A. Domínguez, E. C. Ferrara, A. Fiori, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, V. Gammaldi, F. Gargano, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, L. Guillemot, S. Guiriec, M. Gustafsson, A. K. Harding, E. Hays, John W. Hewitt, D. Horan, X. T. Hou, G. Jóhannesson, M. J. Keith, M. Kerr, M. Krämer, M. Kuss, S. Larsson, L. Latronico, Ju Li, F. Longo, F. Loparco, M. N. Lovellette, P. Lubrano, S. Maldera, Alberto Manfreda, G. Martí-Devesa, M. N. Mazziotta, I. Mereu, P. F. Michelson, N. Mirabal, W. Mitthumsiri, Tsunefumi Mizuno, M. E. Monzani, A. Morselli, Michela Negro, L. Nieder, R. Ojha, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, D. Paneque, A. Parthasarathy, Z. Y. Pei, M. Persic, M. Pesce-Rollins, R. Pillera, H. Poon, T. A. Porter, G. Principe, J. L. Racusin, S. Rainò, R. Rando, Bindu Rani, S. M. Ransom, Paul S. Ray, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, Jayanta Roy, M. Sánchez‐Conde, P. M. Saz Parkinson, J. D. Scargle, L. Scotton, D. Serini, C. Sgrò, E. J. Siskind, D. A. Smith, G. Spandre, R. Spiewak, P. Spinelli, I. H. Stairs, D. J. Suson, Samuel J. Swihart, S. Tabassum, J. B. Thayer, G. Theureau, D. F. Torres, E. Troja, José Manuel Valverde, Zorawar Wadiasingh, K. S. Wood, G. Zaharijaš,

Radio Astronomy Observations and Technology

After large galaxies merge, their central supermassive black holes are expected to form binary systems. Their orbital motion should generate a gravitational wave background (GWB) at nanohertz frequencies. Searches for this background use pulsar timing arrays, which perform long-term monitoring of millisecond pulsars at radio wavelengths. We used 12.5 years of Fermi Large Area Telescope data to form a gamma-ray pulsar timing array. Results from 35 bright gamma-ray pulsars place a 95% credible limit on the GWB characteristic strain of 1.0 × 10 −14 at a frequency of 1 year –1 . The sensitivity is expected to scale with t obs , the observing time span, as t obs − 13 / 6 . This direct measurement provides an independent probe of the GWB while offering a check on radio noise models.