Improving timing sensitivity in the microhertz frequency regime: limits from PSR J1713+0747 on gravitational waves produced by supermassive black hole binaries

Perera, B. B. P.B. B. P.PereraStappers, B. W.B. W.StappersBabak, S.S.BabakKeith, M. J.M. J.KeithAntoniadis, J.J.AntoniadisBassa, C. G.C. G.BassaCaballero, R. N.R. N.CaballeroChampion, D. J.D. J.ChampionCognard, I.I.CognardDesvignes, G.G.DesvignesGraikou, E.E.GraikouGuillemot, L.L.GuillemotJanssen, G. H.G. H.JanssenKaruppusamy, R.R.KaruppusamyKramer, M.M.KramerLazarus, P.P.LazarusLentati, L.L.LentatiLiu, K.K.LiuLyne, A. G.A. G.LyneMcKee, J. W.J. W.McKeeOsłowski, S.S.OsłowskiPERRODIN, DELPHINEDELPHINEPERRODINSanidas, S. A.S. A.SanidasSesana, A.A.SesanaShaifullah, G.G.ShaifullahTheureau, G.G.TheureauVerbiest, J. P. W.J. P. W.VerbiestTaylor, S. R.S. R.Taylor2021-01-082021-01-0820180035-8711http://hdl.handle.net/20.500.12386/29608We search for continuous gravitational waves (CGWs) produced by individual supermassive black hole binaries in circular orbits using high-cadence timing observations of PSR J1713+0747. We observe this millisecond pulsar using the telescopes in the European Pulsar Timing Array with an average cadence of approximately 1.6 d over the period between 2011 April and 2015 July, including an approximately daily average between 2013 February and 2014 April. The high-cadence observations are used to improve the pulsar timing sensitivity across the gravitational wave frequency range of 0.008-5μHz. We use two algorithms in the analysis, including a spectral fitting method and a Bayesian approach. For an independent comparison, we also use a previously published Bayesian algorithm. We find that the Bayesian approaches provide optimal results and the timing observations of the pulsar place a 95 per cent upper limit on the sky-averaged strain amplitude of CGWs to be ≲3.5 × 10-13 at a reference frequency of 1 μHz. We also find a 95 per cent upper limit on the sky-averaged strain amplitude of low-frequency CGWs to be ≲1.4 × 10-14 at a reference frequency of 20 nHz. STAMPAenImproving timing sensitivity in the microhertz frequency regime: limits from PSR J1713+0747 on gravitational waves produced by supermassive black hole binariesArticle10.1093/mnras/sty11162-s2.0-85048472059000439501300016https://academic.oup.com/mnras/article/478/1/218/49909512018MNRAS.478..218PFIS/05 - ASTRONOMIA E ASTROFISICA