"Enhancements and Improved Tests of Relativity with Multi-band GW Observations "

Abstract:   As LIGO continues its third observing run, the added gravitational wave (GW) events provide the promise of further tests of general relativity (GR). In the future the early inspiral of a select number of stellar mass black-hole binaries, like GW150914, will be detectable at low frequencies (10-100 mHz) by the upcoming LISA space mission. Multi-band GW astronomy is a promising avenue for improved tests of GR, both in the weak-field regime and its propagation, constraints on eccentricity, and enhanced parameter estimation techniques, among other possibilities. LISA will also predict, with years of forewarning, the time with which two black holes will merge, which will act as a forewarning to potential EM counterparts and as an unprecedented opportunity to actively configure ground-based detectors to optimize for specific features of a GW signal. One type of feature to optimize for are higher-order modes, beyond the dominant mode, of a GW signal during the ringdown stage of two merged black holes with the goal of improving black hole spectroscopy. This talk will discuss improvements in tests of GR, added benefits of multi-band GW astronomy, and discuss active interferometric techniques to target the central frequencies of subdominant modes and methods to optimize advanced (LIGO and Virgo) and third generation (e.g., Cosmic Explorer and Einstein Telescope) detectors to enhance black-hole spectroscopy.