Probing Supermassive Black Hole Binary Using Radio Observations

It is now well established that almost all massive galaxies have a supermassive black hole (SMBH) at their center. When two galaxies merge, the SMBHs at their center can come together and form a compact supermassive black hole binary (SMBHB). This talk focuses on our on-going efforts to probe such systems using radio observations. In the first half of my talk, I will concentrate on Blazar OJ 287, which is the best candidate to host an SMBH binary in its central engine. Radio observations show that the position angle (PA) of the projected jet of OJ 287 on the sky plane shows temporal variations. I will show how these variations can be explained by the precession of the jet that arises due to the binary nature of the central engine of OJ 287. I will focus on our efforts to model inspiral gravitational waves (GWs) emitted by such binaries during the second part of my talk. This is a deliverable to the International Pulsar Timing Array (IPTA) consortium which aims to detect nanohertz GWs using an array of millisecond radio pulsars. I will describe how to construct PTA response to GWs emitted by spinning SMBHBs in eccentric orbits in an accurate and efficient manner using Keplerian-type parametric solution.