@article{13480, author = {P. de la Parra and S. Kiehlmann and P. Mroz and A. Readhead and A. Synani and M. Begelman and R. Blandford and Y. Ding and F. Harrison and I. Liodakis and W. Max-Moerbeck and V. Pavlidou and R. Reeves and M. Vallisneri and M. Aller and M. Graham and T. Hovatta and C. Lawrence and T. Lazio and A. Mahabal and B. Molina and S. Neill and T. Pearson and V. Ravi and K. Tassis and J. Zensus}, title = {PKS~J0805−0111: A Second Owens Valley Radio Observatory Blazar Showing Highly Significant Sinusoidal Radio Variability — The Tip of the Iceberg}, abstract = {

Owens Valley Radio Observatory (OVRO) observations of supermassive black hole binary (SMBHB) candidate PKS~2131−021 revealed, for the first time, six likely characteristics of the phenomenology exhibited by SMBHB in blazars, of which the most unexpected and critical is sinusoidal flux density variations. We have now identified a second blazar, PKS~J0805−0111, showing significant sinusoidal variations, with an observed period that translates to 1.422±0.005 yr in the rest frame of the z=1.388 object. We generate 106 simulated light curves to reproduce the radio variability characteristics of PKS~J0805−0111, and show that the global probability, considering the \textit{look-elsewhere effect}, indicates that the observed periodicity can be attributed to the red noise tail of the power spectral density, with a p0 value of 7.8×10−5 (i.e. 3.78σ). PKS J0805−0111 displays all six characteristics observed in PKS 2131−021. Taking into account the well-defined OVRO sample size, the false positive probability ∼0.22, but the rare behavior makes this a strong SMBHB candidate. The discovery of a second SMBHB candidate exhibiting these rare characteristics reveals that PKS~2131−021 is not a unique, isolated case. With these two strong cases we are clearly seeing only the tip of the iceberg. We estimate that the number of SMBHB candidates amongst blazars ∼ 1 in 100.

}, year = {2024}, journal = {Submitted}, url = {https://arxiv.org/abs/2408.02645}, }