Our research at the NCBJ is focused on gravitational waves (GWs) which are disturbances in the fabric of spacetime as predicted by Einstein's general theory of relativity (GR). There are various sources of GWs but our group is working on radiation emitted from neutron stars. A neutron star is a collapsed core of a massive star which is supported by the neutron degenerate pressure. These objects emit GWs whenever there is a time-varying quadrupole moment. The GR predicts two polarization states of GWs and they are known as plus (+) polarization and cross (x) polarizations. But GR has some limitations and hence there are many attempts to study some alternative theories of gravity.
Currently, we are studying one of such alternative theories of gravity called Jordan Brans Dicke theory (JBD). This theory incorporates the Mach's principle and hence gravitational constant (G) is not a constant anymore. In general, a metric theory can have six polarization states but there are only three in the JBD theory, two tensor polarizations and one scalar polarization. Unlike in GR, the scalar polarization has also some contribution from the dipole moment. We are in the process of developing computer codes (taking JBD theory into account) to analyze data from LIGO Virgo O3 run.