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PUBLIC VIVA-VOCE NOTIFICATION 11:30 am,Seminar Hall Testing the binary black hole nature of compact binary mergers using gravitational-wave observations Krishnendu N.V Chennai Mathematical Institute. 30-12-19 Abstract We propose a novel method to test the binary black hole (BBH) nature of the compact binaries detectable through gravitational-wave (GW) interferometers and hence constrain the parameter space of other exotic compact objects. The spirit of the test lies in the “no- hair” conjecture for black holes where all properties of a Kerr black hole are characterized by its mass and spin. The method relies on observationally measuring the quadrupole moments of the compact binary constituents induced due to their spins. If the compact the object is a Kerr black hole (BH), its quadrupole moment is expressible solely in terms of its mass and spin. Otherwise, the quadrupole moment can depend on additional parameters (such as the equation of state of the object). The higher-order spin effects in phase and amplitude of a gravitational waveform, which explicitly contains the spin-induced quadrupole moments of compact objects, hence uniquely encode the nature of the compact binary. Thus we argue that an independent measurement of the spin-induced quadrupole moment of the compact binaries from GW observations can provide a unique way to distinguish binary BH systems from binaries consisting of exotic compact objects. We quantify the expected statistical precision in measuring the spin-induced multipole moments using this method by means of the Fisher information matrix. Also, we implement this into the software package developed and currently used by the LIGO scientific collaboration and using this we obtain the first observational bounds on the spin-induced quadrupole moment parameter of a binary black hole system observed by the ground-based gravitational wave detectors. We further compute the projected accuracies with which the spin-induced multipole moments of a compact binary may be estimated with the future ground and space-based gravitational wave observatories. All are invited to attend the viva-voce examination.
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