Detection of gravitational radiation from supermassive black hole binaries via pulsar timing

We consider the problem of detection of long-wave gravitational radiation via irregularities in the time of arrival (TOA) of electromagnetic pulsar pulses. As a GW signal model, the gravitational radiation generated by a black hole binary was taken. In the Bayesian approach, a modified algorithm of timing residuals processing is proposed. It is associated with averaging of the likelihood ratio over the unknown initial phase of the binary system. Data processing of the real pulsar timing array has been performed to detect the GW radiation from supermassive black hole binaries located at the centers of the galaxies NGC4151 and OJ287. The upper limit on GW strain amplitude of these sources has been set. Ways of decreasing this limit up to an astrophysically significant level are discussed.