Limits on the stochastic gravitational wave background from the North American Nanohertz Observatory for Gravitational Waves

P. B. Demorest, R. D. Ferdman, M. E. Gonzalez, D. Nice, S. Ransom, I. H. Stairs, Z. Arzoumanian, A. Brazier, S. Burke-Spolaor, S. J. Chamberlin, J. M. Cordes, J. Ellis, L. S. Finn, P. Freire, S. Giampanis, F. Jenet, V. M. Kaspi, J. Lazio, A. N. Lommen, M. McLaughlinN. Palliyaguru, D. Perrodin, R. M. Shannon, X. Siemens, D. Stinebring, J. Swiggum, W. W. Zhu

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We present an analysis of high-precision pulsar timing data taken as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We have observed 17 pulsars for a span of roughly five years using the Green Bank and Arecibo radio telescopes. We analyze these data using standard pulsar timing models, with the addition of time-variable dispersion measure and frequency-variable pulse shape terms. Sub-microsecond timing residuals are obtained in nearly all cases, and the best rms timing residuals in this set are similar to 30-50 ns. We present methods for analyzing post-fit timing residuals for the presence of a gravitational wave signal with a specified spectral shape. These optimally take into account the timing fluctuation power removed by the model fit, and can be applied to either data from a single pulsar, or to a set of pulsars to detect a correlated signal. We apply these methods to our data set to set an upper limit on the strength of the nHz-frequency stochastic supermassive black hole gravitational wave background of h(c)(1 yr(-1)) <7 x 10(-15) (95%). This result is dominated by the timing of the two best pulsars in the set, PSRs J1713+0747 and J1909-3744.

Original languageEnglish
Article number94
Number of pages25
JournalAstrophysical Journal
Issue number2
Early online date19 Dec 2012
Publication statusPublished - 10 Jan 2013
Externally publishedYes


  • gravitational waves
  • data analysis methods
  • general pulsars
  • individual pulsars (J0030+0451, J0613-0200, J1012+5307, J1455-3330, J1600-3053, J1640+2224, J1643-1224, J1713+0747, J1744-1134, J1853+1308, B1855+09, J1909-3744, J1910+1256, J1918-0642, B1953+29, J2145-0750, J2317+1439)

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