Abstract Details

Conference ID: ASI2017_645
Title : Testing the binary black hole nature of compact binary coalescences using gravitational wave observations
Authors and Co-Authors : K G Arun, Chennai Mathematical Institute, Chennai C K Mishra, ICTS-TIFR, Bangalore and IIT Madras
Abstract Type : Oral
Abstract Category : General Relativity and Cosmology
Abstract : The first Advanced LIGO (Laser Interferometric Gravitational Wave Observatory) observing run (O1) detected gravitational wave (GW) signals from two binary black hole (BH) mergers. The detectors are now ready for their second observing run which is poised to detect many more of such signals (in addition to, perhaps, signals of other types). While the detected signals are completely consistent with the merger of binary BHs, alternatives which might mimic the features of a binary BH merger cannot be ruled out. We propose a new way of distinguishing a binary BH merger from mergers of binaries involving BH mimickers by measuring the quadrupole moments of the binary constituents (or their linear combination) which explicitly appear in the gravitational waveforms within the post-Newtonian (PN) approximation. Spin-induced quadrupole moment of a compact object may be defined as $Q=-\kappa/:\chi^2/:m^3$, where $\kappa=1$ for BHs by "no-hair conjuncture" where as it can vary from 4 to 8 for a Neutron Star (NS) depending up on different equation of states. For exotic compact objects like boson stars the $\kappa$ value ranges roughly from 10 to 150. So the accurate measurement of the $\kappa$ value can uniquely probe the BBH nature of the compact binary system. Using Fisher Information Matrix, we estimate the accuracy which $\kappa$ can be measured with advanced LIGO-like detectors and show that the proposed method offers a novel way to constrain the parameter space of BH mimickers. Implications for third generation telescopes and space-based detectors are also discussed.